FOUS30 KWBC 181550
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1150 AM EDT Thu Sep 18 2025

Day 1
Valid 16Z Thu Sep 18 2025 - 12Z Fri Sep 19 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR MUCH OF
SOUTHERN CALIFORNIA AND SOUTHWESTERN ARIZONA...

...Southwest U.S...

The previous discussion is largely in good shape for this=20
morning's update. No substantial updates to the ERO for Day 1 were=20
needed as the impressive moisture continues to advect northward=20
into the region which along with an axis of instability develops=20
bringing a greater risk of heavy rainfall and flash flooding=20
potential today.=20

---previous discussion---

Remnant moisture from post-tropical cyclone Mario will continue to advect poleward with California firmly in the cross-hairs for elevated
moisture (PWATs 2-4 deviations above normal) to move into the
southern half of the state during the entirety of the D1 period.
Energy from Mario will lag the initial low to mid-level moisture
surge, but eventually will enter into the area by the late-morning
hours today, prompting an uptick in the areal coverage of
convection over the southern half of the state into the Lower
Colorado Basin between CA/AZ. The last succession of HREF runs,
including this evenings 00z suite was pretty pronounced in the
indication of precip totals between 2-4" potentially impacting some
of the coastal ranges of CA into the adjacent valley just north of
the Transverse and Peninsular Ranges. There's also a pretty good
indication of scattered to widespread convective development later
this morning, through the afternoon period across the lower deserts
of southeast CA to the neighboring Colorado Basin at the CA/AZ
line. This was the area of greatest change when it came to the
magnitude of the signal when assessing the run to run differences
over the past iterations of the HREF suite. Ensemble bias corrected
QPF was also adjusted upward from its previous forecasts across the aforementioned area, a testament to the improving signature for
local flash flood prospects in that general area. HREF neighborhood
probs for >1" across the deserts are upward of 50-80% now with
70-90+% located within the Transverse and Peninsular Ranges during
the period, a reflection of the heightened threat for at least
moderate rainfall, enough to spur high runoff concerns in the
terrain with several burn scars still present in-of those mountain
chains. Rates will be sufficient considering the deep moist
environment brought on by the advection of the tropical moisture
flux involved with Mario, another reason for the threat to be
leaning towards the higher side as elevated rates are a significant
driver to flash flooding historically across CA.

The previous SLGT was expanded a bit to account for the trends in
hi-res guidance and the conditioning of the environment favoring
the higher moisture anomalies being advected further north into CA.
The threat is on the higher end of the SLGT threshold with the
"saving grace" in this entire setup being the more progressive mean
flow helping push everything through in relatively faster time than
what is customary for higher level risks. That still doesn't deter
the fact that scattered flash flood prospects are becoming more
certain in the the areas outlined in the SLGT risk with a potential
for targeted upgrade plausible if conditions warrant.

...Central U.S...

16Z Update:=20

For this update, still think the flash flood risk is fairly
isolated across the Northern Plains and Upper Midwest given the
relative lack of deep instability, however the dynamical support
may allow for some embedded stronger cores of locally intense
rainfall. To the south across KS/MO/OK/AR, greater instability
should promote more intense rain rates, but coverage of convection
and whether it will be enough to cause flooding issues is more
uncertain. For now, maintained the Marginal Risk area largely
unchanged, aside from some adjustments on the western edges based
on current activity but the next update may be able to make more=20
greater adjustments.=20

Taylor

---previous discussion---

Current WV satellite depicts a broad upper low (ULL) with the center
positioned over SD with a surface low analyzed almost underneath
the ULL meaning the confidence in an occlusion process beginning
soon is very high. Once we see the occlusion phase begin, we'll see
the slow degradation of the prominent deformation field across the
Dakotas over the course of the forecast leading to decreasing
rates and expected totals compared to what transpired the period
prior. As a result, flash flooding concerns will be relatively
isolated given the more stratiform rain process with the convective
threat positioned further east into the Mississippi Valley. 00z
HREF was not very robust for heavy rain prospects in any one area,
but there were several locations that will stand to benefit from
locally heavier convection as the cold front continues to migrate
eastward and drive a broad surface ascent pattern downstream of the
low. A few stronger mid-level vorticity maxima will help amplify
the threat in a few areas, mainly in the Missouri and Mid-
Mississippi Valleys later this afternoon as a stronger mid-level
shortwave continues to propagate into the region from its overnight
trajectory. HREF blended mean QPF distribution outlines this area
fairly well and matches with the modest >3" probabilities situated
over eastern OK up into MO. Overall, the entire setup with a slowly
decaying, or steady state low will contribute just another period
of widely scattered flash flood prospects from the Northern Plains
over and through the northern two-thirds of the Mississippi Valley.
The previous MRGL was general maintained with some adjustments
based on the latest hi-res ensemble probs and blended mean QPF
footprint.

...Southeast Florida...

16Z Update: Some drier is working eastward across the Keys this
morning, evident by the 12Z sounding from Key West which showed
substantial dry, stable layer from near the surface to around 700
mb. Current radar imagery suggests most of the intense activity has
waned and/or is mainly offshore, and the 12Z hi-res guidance is
less bullish on a widespread heavy rainfall day. As a result, the
risk area was removed from the Keys. However, there is enough=20
support in the guidance and environmental ingredients to maintain=20
the Marginal Risk over southeast Florida in the most urbanized=20
corridor.=20

Taylor

---previous discussion---

PWATs across south FL remain elevated with KEYW and KMFL both
coming in with values of 2.08" and 2.19", respectively meaning the
deep layer moisture forecast the past several days is firmly
entrenched over the region. Several shortwave perturbations will
advect northeast out of the Florida Straits and nearby Cuba with
the presence of a Cuban outflow being picked up in the radar/sat
composite over the past few hours. This is actually well-forecast
via some of the CAMs suite, a likely indicator that the future
trends within the models probably hold merit for a threat of heavy
rain to cross into the Key and the southern Peninsula in the early
morning hours. As the boundary migrates to the northeast, expect
copious showers/storms to gallivant through the area dropping
locally enhanced rainfall with rates between 2-3"/hr pretty much a
given in a few of the convective cores just due to the environment
in place. Models are still in flux on the exact locations of where
heavier rain will occur, but the neighborhood probs for >3" running
between 50-80% and >5" between 25-35% across both the Keys and
southeast FL are sufficient for a continuation of the previous MRGL
risk through the forecast cycle. Will monitor closely for potential
targeted upgrades, but the setup is certainly favoring at least
isolated flash flood potential within those two corridors,
particularly more urban zones due to impervious surface runoff.

Kleebauer


Day 2
Valid 12Z Fri Sep 19 2025 - 12Z Sat Sep 20 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF THE
CENTRAL SIERRA NEVADA AND CENTRAL VALLEY OF CALIFORNIA...

...California...

Remnant energy from what is left over from Mario will pivot up into
Central CA early Friday allowing for a continuation of heavy
rainfall prospects over the region as PWATs surge to between 3-4
deviations above normal. Guidance is keying on prevailing upslope
flow and focused ascent within the Central Sierra of CA with a
myriad of thunderstorms lingering in the Central Valley. The
environmental conditions favor locally enhanced convective cores
which could spell problems for those towns in the valleys, as well
as runoff in the terrain. HREF neighborhood probs for >1" are very
high (70-90%) within the above areas with mainly modest >2" probs
centered over the Central Valley and adjacent Sierra foothills.
Considering some overlap of heavy rain from D1 into D2, the threat
seems worthy of a targeted upgrade in these two zones to account
for the continued risk bleeding from period to period. The good
news is the setup looks to wane the second half of the forecast
cycle as energy pushes out of the region and we see a slow
improvement in the moisture anomalies. This would spell the end
for the threat of flash flooding and much of the rain prospects.

...Southwest...

Moisture increases across all of the Southwest CONUS will aid in
favorable environmental conditions for locally heavy convective
rainfall during the period of diurnal heating on Friday into early
Saturday. HREF mean QPF is relatively tame overall, but some of the
CAMs are more robust in their depictions of isolated 2+" totals,
especially across the Mogollon Rim and Southeast AZ terrain leading
to a broad MRGL risk maintenance from previous forecast. The
threat for flash flooding will likely lie as far north as the
I-70/15 junction and points west over UT/NV with slot canyons and
dry arroyos as the primary targets for flash flooding as is
customary in these setups. The threat for a targeted upgrade is on
the table, but will need to assess the evolution of the mid-level
vorticity maxima ejecting out of CA to the east over the course of
time. The most favored areas will likely be those outlined above.
For now, the MRGL risk will suffice.

...Mississippi Valley to ArkLaTex...

Occluded low over the Upper Midwest will continue to spin with a
dumbbelling mid-level shortwave pivoting southeast out of the
Dakotas allowing for a secondary broad ascent pattern to
materialize downstream over the Mississippi Valley. To the south,
thunderstorms will fire along a decaying front positioned over the Mid-Mississippi Valley down into the ArkLaTex with ample
instability and moisture to fuel another isolated flash flood
threat when assessing individual CAMs and ensemble bias corrected
outputs. The threat is similar to the previous period, perhaps even
a touch less robust considering the occlusion phase well in
progress by this point in the forecast. Overall, this threat was
deemed enough for a broad MRGL risk to stay in place, but there's
some potential for a targeted upgrade, pending better overlap from
model guidance on any particular area from TX to the Upper Midwest.

...Southeast Florida...

The southeast coast of Florida will be hanging on to the last bit
of remaining anomalous moisture as the pattern starts to shift away
from persistence of the preceding three periods. The MRGL was
maintained given some of the guidance hanging on to heavier
convection right along the coast with modest probabilities for >3"
lingering from Miami up to Daytona Beach. That was enough to
maintain continuity of a MRGL for at least one more period.

Kleebauer


Day 3
Valid 12Z Sat Sep 20 2025 - 12Z Sun Sep 21 2025


...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE CENTRAL AND SOUTHERN PLAINS INTO THE MISSOURI VALLEY...

...Central U.S...

Shortwave ejection out of the Great Basin/Four Corners area will
migrate into the Central and Southern Plains by Saturday afternoon
providing a more focused large scale ascent pattern during peak
diurnal instability. Ensemble means are relatively modest in their
QPF distribution and magnitude, signaling 1-2" of rainfall
currently in their depictions. Individual deterministic is
certainly a little more robust, but nothing that would promote a
more substantial risk. This correlates well with moisture anomalies
hovering between normal and +1 deviations when assessing the latest
NAEFS meaning the threat is warranted, but well-within the
threshold of a MRGL risk. As a result, kept the previous MRGL risk
and expanded to account for some uncertainty in the spatial
coverage of expected convection by this time frame.

Kleebauer


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!-dKZvbgU6fTxbR--Zv_ItwcAubVxSxQk9IPptIBR7wwn= mRPbYx_UlhCaWLOo5STwoPihZ1HpEmvSnnSsmnVbs5JQMs0$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!-dKZvbgU6fTxbR--Zv_ItwcAubVxSxQk9IPptIBR7wwn= mRPbYx_UlhCaWLOo5STwoPihZ1HpEmvSnnSsmnVbVgr67ww$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!-dKZvbgU6fTxbR--Zv_ItwcAubVxSxQk9IPptIBR7wwn= mRPbYx_UlhCaWLOo5STwoPihZ1HpEmvSnnSsmnVbvZ1z0QQ$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 190100
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
900 PM EDT Thu Sep 18 2025

Day 1
Valid 01Z Fri Sep 19 2025 - 12Z Fri Sep 19 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR MUCH OF
SOUTHERN CALIFORNIA AND SOUTHERN-CENTRAL ARIZONA...

...Southwest U.S...

Difluent upper level flow is quite evident across southern CA and
AZ per the mid/upper level satellite water vapor loops this=20
evening. The latest guidance indicates the upper divergence will
likely get a boost overnight within the left exit region of an
approaching 70-90 kt upper level jet streak -- including a broader
area across southern and central AZ. As a result, coupled with the
latest observational trends (mosaic radar and FFWs especially), as
well as the latest HREF and RRFS rainfall exceedance probabilities,
have expanded the Slight Risk to include a larger portion of
central and southern AZ.

Hurley

---previous discussion---

Remnant moisture from post-tropical cyclone Mario will continue to advect poleward with California firmly in the cross-hairs for elevated
moisture (PWATs 2-4 deviations above normal) to move into the
southern half of the state during the entirety of the D1 period.
Energy from Mario will lag the initial low to mid-level moisture
surge, but eventually will enter into the area by the late-morning
hours today, prompting an uptick in the areal coverage of
convection over the southern half of the state into the Lower
Colorado Basin between CA/AZ. The last succession of HREF runs,
including this evenings 00z suite was pretty pronounced in the
indication of precip totals between 2-4" potentially impacting some
of the coastal ranges of CA into the adjacent valley just north of
the Transverse and Peninsular Ranges. There's also a pretty good
indication of scattered to widespread convective development later
this morning, through the afternoon period across the lower deserts
of southeast CA to the neighboring Colorado Basin at the CA/AZ
line. This was the area of greatest change when it came to the
magnitude of the signal when assessing the run to run differences
over the past iterations of the HREF suite. Ensemble bias corrected
QPF was also adjusted upward from its previous forecasts across the aforementioned area, a testament to the improving signature for
local flash flood prospects in that general area. HREF neighborhood
probs for >1" across the deserts are upward of 50-80% now with
70-90+% located within the Transverse and Peninsular Ranges during
the period, a reflection of the heightened threat for at least
moderate rainfall, enough to spur high runoff concerns in the
terrain with several burn scars still present in-of those mountain
chains. Rates will be sufficient considering the deep moist
environment brought on by the advection of the tropical moisture
flux involved with Mario, another reason for the threat to be
leaning towards the higher side as elevated rates are a significant
driver to flash flooding historically across CA.

The previous SLGT was expanded a bit to account for the trends in
hi-res guidance and the conditioning of the environment favoring
the higher moisture anomalies being advected further north into CA.
The threat is on the higher end of the SLGT threshold with the
"saving grace" in this entire setup being the more progressive mean
flow helping push everything through in relatively faster time than
what is customary for higher level risks. That still doesn't deter
the fact that scattered flash flood prospects are becoming more
certain in the the areas outlined in the SLGT risk with a potential
for targeted upgrade plausible if conditions warrant.

...Central U.S...

16Z Update:

For this update, still think the flash flood risk is fairly
isolated across the Northern Plains and Upper Midwest given the
relative lack of deep instability, however the dynamical support
may allow for some embedded stronger cores of locally intense
rainfall. To the south across KS/MO/OK/AR, greater instability
should promote more intense rain rates, but coverage of convection
and whether it will be enough to cause flooding issues is more
uncertain. For now, maintained the Marginal Risk area largely
unchanged, aside from some adjustments on the western edges based
on current activity but the next update may be able to make more
greater adjustments.

Taylor

---previous discussion---

Current WV satellite depicts a broad upper low (ULL) with the center
positioned over SD with a surface low analyzed almost underneath
the ULL meaning the confidence in an occlusion process beginning
soon is very high. Once we see the occlusion phase begin, we'll see
the slow degradation of the prominent deformation field across the
Dakotas over the course of the forecast leading to decreasing
rates and expected totals compared to what transpired the period
prior. As a result, flash flooding concerns will be relatively
isolated given the more stratiform rain process with the convective
threat positioned further east into the Mississippi Valley. 00z
HREF was not very robust for heavy rain prospects in any one area,
but there were several locations that will stand to benefit from
locally heavier convection as the cold front continues to migrate
eastward and drive a broad surface ascent pattern downstream of the
low. A few stronger mid-level vorticity maxima will help amplify
the threat in a few areas, mainly in the Missouri and Mid-
Mississippi Valleys later this afternoon as a stronger mid-level
shortwave continues to propagate into the region from its overnight
trajectory. HREF blended mean QPF distribution outlines this area
fairly well and matches with the modest >3" probabilities situated
over eastern OK up into MO. Overall, the entire setup with a slowly
decaying, or steady state low will contribute just another period
of widely scattered flash flood prospects from the Northern Plains
over and through the northern two-thirds of the Mississippi Valley.
The previous MRGL was general maintained with some adjustments
based on the latest hi-res ensemble probs and blended mean QPF
footprint.

...Southeast Florida...

16Z Update: Some drier is working eastward across the Keys this
morning, evident by the 12Z sounding from Key West which showed
substantial dry, stable layer from near the surface to around 700
mb. Current radar imagery suggests most of the intense activity has
waned and/or is mainly offshore, and the 12Z hi-res guidance is
less bullish on a widespread heavy rainfall day. As a result, the
risk area was removed from the Keys. However, there is enough
support in the guidance and environmental ingredients to maintain
the Marginal Risk over southeast Florida in the most urbanized
corridor.

Taylor

---previous discussion---

PWATs across south FL remain elevated with KEYW and KMFL both
coming in with values of 2.08" and 2.19", respectively meaning the
deep layer moisture forecast the past several days is firmly
entrenched over the region. Several shortwave perturbations will
advect northeast out of the Florida Straits and nearby Cuba with
the presence of a Cuban outflow being picked up in the radar/sat
composite over the past few hours. This is actually well-forecast
via some of the CAMs suite, a likely indicator that the future
trends within the models probably hold merit for a threat of heavy
rain to cross into the Key and the southern Peninsula in the early
morning hours. As the boundary migrates to the northeast, expect
copious showers/storms to gallivant through the area dropping
locally enhanced rainfall with rates between 2-3"/hr pretty much a
given in a few of the convective cores just due to the environment
in place. Models are still in flux on the exact locations of where
heavier rain will occur, but the neighborhood probs for >3" running
between 50-80% and >5" between 25-35% across both the Keys and
southeast FL are sufficient for a continuation of the previous MRGL
risk through the forecast cycle. Will monitor closely for potential
targeted upgrades, but the setup is certainly favoring at least
isolated flash flood potential within those two corridors,
particularly more urban zones due to impervious surface runoff.

Kleebauer


Day 2
Valid 12Z Fri Sep 19 2025 - 12Z Sat Sep 20 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF THE
CENTRAL SIERRA NEVADA AND CENTRAL VALLEY OF CALIFORNIA...

20Z Update: The Slight Risk over portions of CA continues to look
with the peak of the intense rain likely overnight into early
Friday morning. Otherwise, the rest of the areas look good, however
for South Florida, the best moisture is expected to move east of
the area by tomorrow, significantly reducing the rainfall threat
such that the Marginal Risk was dropped per coordination with WFO
MFL.

Taylor

...California...

Remnant energy from what is left over from Mario will pivot up into
Central CA early Friday allowing for a continuation of heavy
rainfall prospects over the region as PWATs surge to between 3-4
deviations above normal. Guidance is keying on prevailing upslope
flow and focused ascent within the Central Sierra of CA with a
myriad of thunderstorms lingering in the Central Valley. The
environmental conditions favor locally enhanced convective cores
which could spell problems for those towns in the valleys, as well
as runoff in the terrain. HREF neighborhood probs for >1" are very
high (70-90%) within the above areas with mainly modest >2" probs
centered over the Central Valley and adjacent Sierra foothills.
Considering some overlap of heavy rain from D1 into D2, the threat
seems worthy of a targeted upgrade in these two zones to account
for the continued risk bleeding from period to period. The good
news is the setup looks to wane the second half of the forecast
cycle as energy pushes out of the region and we see a slow
improvement in the moisture anomalies. This would spell the end
for the threat of flash flooding and much of the rain prospects.

...Southwest...

Moisture increases across all of the Southwest CONUS will aid in
favorable environmental conditions for locally heavy convective
rainfall during the period of diurnal heating on Friday into early
Saturday. HREF mean QPF is relatively tame overall, but some of the
CAMs are more robust in their depictions of isolated 2+" totals,
especially across the Mogollon Rim and Southeast AZ terrain leading
to a broad MRGL risk maintenance from previous forecast. The
threat for flash flooding will likely lie as far north as the
I-70/15 junction and points west over UT/NV with slot canyons and
dry arroyos as the primary targets for flash flooding as is
customary in these setups. The threat for a targeted upgrade is on
the table, but will need to assess the evolution of the mid-level
vorticity maxima ejecting out of CA to the east over the course of
time. The most favored areas will likely be those outlined above.
For now, the MRGL risk will suffice.

...Mississippi Valley to ArkLaTex...

Occluded low over the Upper Midwest will continue to spin with a
dumbbelling mid-level shortwave pivoting southeast out of the
Dakotas allowing for a secondary broad ascent pattern to
materialize downstream over the Mississippi Valley. To the south,
thunderstorms will fire along a decaying front positioned over the Mid-Mississippi Valley down into the ArkLaTex with ample
instability and moisture to fuel another isolated flash flood
threat when assessing individual CAMs and ensemble bias corrected
outputs. The threat is similar to the previous period, perhaps even
a touch less robust considering the occlusion phase well in
progress by this point in the forecast. Overall, this threat was
deemed enough for a broad MRGL risk to stay in place, but there's
some potential for a targeted upgrade, pending better overlap from
model guidance on any particular area from TX to the Upper Midwest.

Kleebauer


Day 3
Valid 12Z Sat Sep 20 2025 - 12Z Sun Sep 21 2025


...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE CENTRAL AND SOUTHERN PLAINS INTO THE MISSOURI VALLEY...

...Central U.S...

Shortwave ejection out of the Great Basin/Four Corners area will
migrate into the Central and Southern Plains by Saturday afternoon
providing a more focused large scale ascent pattern during peak
diurnal instability. Ensemble means are relatively modest in their
QPF distribution and magnitude, signaling 1-2" of rainfall
currently in their depictions. Individual deterministic is
certainly a little more robust, but nothing that would promote a
more substantial risk. This correlates well with moisture anomalies
hovering between normal and +1 deviations when assessing the latest
NAEFS meaning the threat is warranted, but well-within the
threshold of a MRGL risk. As a result, kept the previous MRGL risk
and expanded to account for some uncertainty in the spatial
coverage of expected convection by this time frame.

Kleebauer


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!-geNu54zfaXCF7NeZnWsBggE9wXIecCiHMF0cma2A5j4= wyyfC4nSK7eRLCxh2Ywj9EGg_CrvAdZEgbameabyDpVMKWQ$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!-geNu54zfaXCF7NeZnWsBggE9wXIecCiHMF0cma2A5j4= wyyfC4nSK7eRLCxh2Ywj9EGg_CrvAdZEgbameabyby35foY$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!-geNu54zfaXCF7NeZnWsBggE9wXIecCiHMF0cma2A5j4= wyyfC4nSK7eRLCxh2Ywj9EGg_CrvAdZEgbameabymE-BqEw$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 210039
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
839 PM EDT Sat Sep 20 2025

Day 1
Valid 01Z Sun Sep 21 2025 - 12Z Sun Sep 21 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE SOUTHERN PLAINS, OZARKS, & CENTRAL APPALACHIANS...

...Southern Plains and Ozarks...
A festering area of convection across OK & near the MO/AR border continues
to be sufficient for a Marginal flooding threat. Earlier rainfall
should have partially saturated soils, and with the topography
across some locales, at least isolated instances of flash flooding
are anticipated. A later complex will likely form very late=20
tonight near the Red River of the South. These storms should also=20
pose an isolated overnight flash flooding risk. Regionally, there
is a pool of 1000-3500 J/kg of MU CAPE to feed thunderstorms and
about 25 kts of effective bulk shear which should lead to
organization at times. With precipitable water values ~1.5", hourly
amounts to 2" with local amounts to 4" should be possible.


...Central Appalachians...
Ongoing pulse convection should continue for several more hours=20
near the Virginia/West Virginia border before MU CAPE fades and/or=20
CIN wins out. Precipitable water values above 1.25" along with MU=20
CAPE of up to 1000 J/kg are feeding them currently. Until they=20
dissipate, hourly amounts to 2" are possible as they move slowly=20
near the rough topography, continuing the Marginal Risk of=20
excessive rainfall.

Roth


Day 2
Valid 12Z Sun Sep 21 2025 - 12Z Mon Sep 22 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE CENTRAL PLAINS, MID MISSISSIPPI VALLEY, AND THE SOUTHWEST...

...19Z Update...

...Plains to Mid-Mississippi Valley...

Overall across the middle of the country, the signal for heavy rain
on Sunday remains quite diffuse. There will be a corridor where
heavier rain will be more likely, which includes the Marginal Risk
region from Oklahoma through Illinois. However, the guidance is in
otherwise poor agreement on where any clusters of storms will
develop and how much rain they will produce. Thus, taking
antecedent dry soil conditions into account across nearly all of
the Marginal Risk area, it remains a rather low-end Marginal.

...Southwest...

Very few changes needed across the Southwest as monsoonal moisture
in place across much of Arizona and portions of the California
Deserts may allow for some limited shower and thunderstorm
development. A positively tilted longwave trough approaching the
area from the northwest will increase the large scale forcing in
the area, which should allow for some "slopover" of any storms into
the normally drier desert areas. Couple that with the western
portion of the area (far southern California and far western
Arizona) having recently picked up locally flooding rains, the
Marginal Risk remains in place largely unchanged. As usual, burn
scar areas will be particularly susceptible to renewed flooding
should heavy rains occur over or near them.

Wegman

...Previous Discussion...

...Eastern Kansas and northeastern Oklahoma to southern Illinois...

Deepening moisture (PWs above 1.5 inches) along an axis of
strengthening southerly to southwesterly flow ahead an amplifying
upper trough will fuel showers and storms, possibly producing
heavy amounts. While models differ significantly on the details,
the general consensus indicates widespread precipitation is likely,
with locally heavy amounts of 1-2 inches possible.

...Southwest...

An upper low dropping to the south along the California coast will
slow as it becomes cutoff west of Southern California. Southerly
flow ahead of the system will support increasing moisture and the
chances for precipitation across parts of Southern California and
Arizona. Both the GFS and ECMWF show PW anomalies increasing to 2.5
to 3 standard deviations above normal across far Southern
California through the lower Colorado Basin into Arizona.

Pereira


Day 3
Valid 12Z Mon Sep 22 2025 - 12Z Tue Sep 23 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE SOUTHWEST AND FROM KANSAS AND OKLAHOMA TO THE OHIO VALLEY...

...19Z Update...

...Kansas/Oklahoma to the Ohio Valley...

A plume of moisture streaming off the Gulf will collide with a
stalled frontal boundary from Kansas through the Ohio Valley on
Monday. Expect multiple clusters of storms riding up that boundary
from southwest to northeast to douse the region with periodically
heavy rain. The details of where any such clusters of storms are
likely to form remain highly uncertain. Thus, while the signal for
heavy rain across the region is significantly higher than the Day
2/Sunday period, there remains little agreement on where and
whether any persistent heavy rain will significantly impact any
areas hit with heavy rain on previous days. Thus, once again taking
into account antecedent conditions, which only get drier the
further north and east you go, the large Marginal Risk area across
the area remains valid.

...Southwest...

Very little has changed in the forecast with another day of
afternoon showers and storms likely to impact much of eastern
Arizona into portions of western New Mexico Monday afternoon. With
ridging aloft and therefore no larger scale areas of forcing, the
storms will likely be tied to topography, such as the Mogollon Rim,
limiting the flash flood threat to isolated instances.

Wegman

...Previous Discussion...

...Kansas and Oklahoma to the Ohio Valley...

Unsettled weather will continue, with the footprint for potentially
heavy rain expanding as energy moving through the base of a broad
upper trough interacts with deep moisture that will be supported
persistent southwesterly flow. While models generally agree on a
large footprint of moderate to heavy amounts, they lack agreement
on the details. At least locally heavy amounts are expected,
especially within the western portions of the highlighted area as
a well-defined shortwave dives southeast and is expected to
interact with a pool of deepening moisture along a strong
southwesterly low level jet. Given the indication of 2-3 inches in
some of the models, which is forecast to fall in addition to the
previous days' amounts, an upgrade to a Slight Risk may be
forthcoming if the signal persists and the guidance moves into
better agreement.

...Southwest...

An upper low is forecast to remain cutoff and drift slowly east
along the Southern California coast. Anomalous moisture in place
across Arizona is expected to spread east into parts of New Mexico,
extending the chances for showers and storms, with potentially
heavy amounts into the region.

Pereira


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!5dYUTd9YHCCo5BqlE_nbMUgURPa5l2yb1Rem_wl9VvKb= FhcyE-LhEl4C9yiWyMCBZUNQFvF60fl3YI89yJAdkURTWtk$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!5dYUTd9YHCCo5BqlE_nbMUgURPa5l2yb1Rem_wl9VvKb= FhcyE-LhEl4C9yiWyMCBZUNQFvF60fl3YI89yJAdOOsCxlw$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!5dYUTd9YHCCo5BqlE_nbMUgURPa5l2yb1Rem_wl9VvKb= FhcyE-LhEl4C9yiWyMCBZUNQFvF60fl3YI89yJAd8G0duIM$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 211902
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
302 PM EDT Sun Sep 21 2025

Day 1
Valid 16Z Sun Sep 21 2025 - 12Z Mon Sep 22 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL IN THE VICINITY OF
THE KANSAS/OKLAHOMA/ARKANSAS/MISSOURI BORDER AREA...

...16Z Update...

...Central/Southern Plains to the Mid-Mississippi Valley...

The inherited Slight Risk for portions of the
Missouri/Kansas/Oklahoma/Arkansas region has been expanded
southward across much of far eastern Oklahoma with this update. 12Z
guidance has some agreement that once the area of showers and
storms moving along the OK/TX border moves through eastern Oklahoma
and into Arkansas later this afternoon, a renewed area of
convection forms along a trailing boundary somewhere in eastern
Oklahoma. While the agreement on where that trailing boundary will
set up is poor, there is far better agreement that it may result in
multiple hours of trailing thunderstorms in a narrow corridor
aligned northwest to southeast. Perhaps with some persistence bias
given the events of last night where narrow corridors of 4-6 inches
of rain fell further north, resulting in localized flash flooding,
confidence has increased for such an event to occur again a bit
further south tonight. While rainfall amounts are expected to be
lesser in this area tonight, any additional rainfall on top of
areas hard hit tonight could cause renewed stream, creek, and river
rises, so the Slight Risk in that area is maintained.

Further north into Missouri, there is less confidence due to lesser instability. While the potential for training is high, how strong
those storms get and how long they persist and where those most
persistent bands set up across Missouri and into Illinois is of low
certainty. Thus, for now the Marginal is maintained, but the Slight
may need to be expanded on short-notice should the storms show the
ability to produce heavy rains for an extended period of time.

...Southwest...

Few changes were needed, as the forecast described below in the
previous discussion remains valid.

Wegman

...Previous Discussion...

...Central-Southern Plains into the Mid Mississippi Valley...
Additional shortwave energy will be diving east southeastward
through the base of the mean trof centered through the Central to
Southern Plains into the Middle Mississippi Valley. These height
falls will help strengthen the low level west south west to
southwesterly flow into a west to east northeasterly oriented low
level boundary stretching from the Southern Plains into the Middle
Mississippi Valley. This will support another round of convection
pushing east from central to eastern KS/OK into much of MO,
northwest AR and central to Southern IL. A slight risk area was
added in the vicinity of the KS/OK/AR/MO border area that has seen
heavy rains over the past 24 hours and may see additional heavy
totals later in the upcoming day 1 period. Otherwise, there were no
significant changes made to the previous marginal risk area, that
continues to fit well with the latest axis of high HREF
neighborhood probabilities for 1 and 2"+ amounts during the
upcoming day 1 period. Across these areas, relative soil moistures
remain very low, which should help mitigate runoff issues, at least
initially.

...Southern California into Arizona...
The closed low initially off the Central California coast will be
drifting only slowly southward day 1 to a position off the
Southern California coast. A jet streak on the eastern side of this
upper trof will keep favorable right entrance region jet dynamics
over Southern CA into Arizona. This will help accentuate lift in
an axis of anomalous PW values, 1 to 3+ standard deviations above
the mean that are expected to persist across these areas day 1.
This should support potential for additional widespread scattered
convection, locally heavy rains and isolated runoff issues.

Oravec

Day 2
Valid 12Z Mon Sep 22 2025 - 12Z Tue Sep 23 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM THE
CENTRAL TO SOUTHERN PLAINS, MIDDLE TO LOWER MISSISSIPPI VALLEY AND
OHIO VALLEY AND ACROSS ARIZONA INTO WESTERN NEW MEXICO...

19z Update: There may be an opportunity to add in a Slight risk or
two on future updates, by for now we will maintain the broad
Marginal risk from portions of the Plains into the OH and TN=20
Valley. The 12z high res guidance indicates one area of heavier
rainfall (upwards of 2-4") across portions of central KY and TN.
Considered a targeted Slight risk here, but this is a notable QPF
uptick from the previous cycle, and would prefer to wait for
another cycle to see if the signal remains consistent. On top of=20
that, FFG is quite high over this area, and so even with the=20
increased QPF signal the HREF probabilities of exceeding 3hr FFG=20
remain low.

Another area to watch is western to central KS into northern OK where
a convective complex is expected Monday night into early Tuesday.=20
At least some training appears probable, but the extent remains a=20
bit uncertain. Thus the Marginal risk should suffice for now.

Chenard

...Previous Discussion...

...Mid to Lower Mississippi Valley into the Ohio Valley...
The height falls pushing east southeastward day 1 into the Central
to Southern Plains and toward the Mid Mississippi Valley will
continue to move eastward through the Ohio Valley day 2. Well
defined large scale lift in an axis of above average PW values, 1
to 1.5+ standard deviations above the mean, will support the
likelihood of widespread moderate to heavy precipitation in an
axis from northern AR, far southeast MO, far southeast IL, western
to central KY, much of IN and OH. At the moment the convection
across these areas may be fairly progressive. This and very low
relative soil moistures, much of the area in moderate to severe
drought, will keep the risk level at marginal for the time being.
With respect to changes to the previous issuance, the northern edge
of the marginal risk was trimmed to the south by about 50-75 miles
to account for the latest model consensus.

...Central to Southern Plains...
The marginal risk area from the previous issuance was expanded
slightly westward into western KS to cover the model spread with
the next round of convection forming ahead of the upstream
amplifying height falls dropping southeastward late
day 1 from the Northern Rockies into the Central Rockies/Lee of the
Central Rockies on day 2. The GFS and NAM begin to diverge day 2
with the track of this closing off mid to upper level center, with
the NAM taking a more southeastward track into the Central Plains,
while the GFS takes a more south southeastward track into the
Central Rockies. The NAM solution, at the moment, is an outlier
with the EC, UKMET and CMC more in line with the GFS. The
differing mid to upper evolutions have more of a qpf impact over
south central WY into north central CO, where the more southeast
NAM solution is much lighter than the remainder of the guidance. Do
not believe there will be any runoff issues farther northwest
across CO/WY given lack of instability. While models differ farther
to the southeast, there are still non NAM solutions that have
potentially heavy rains as far northwest as northwest KS day 2,
supporting the west northwest expansion from the previous
issuance.

...Southwest...
The closed low off the Southern CA coast day 1 is expected to move
little on day 2. The right entrance region of the jet streak to
the east of this closed low will push eastward from its day 1
position, but continue to support uvvs enhancement in the above
average PW axis, 1 to 3 standard deviations above the mean, that
will remain in place across Southern CA into the Southwest.
Additional scattered convection across these areas will support
localized heavy amounts and isolated runoff issues. The previous
marginal risk area was expanded westward into southeast CA to cover
the model qpf spread.

Oravec

Day 3
Valid 12Z Tue Sep 23 2025 - 12Z Wed Sep 24 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHERN
MISSOURI, NORTHERN ARKANSAS, NORTHEAST OKLAHOMA AND SOUTHEAST
KANSAS...

19z Update: On Tuesday an uptick in the flash flood risk is=20
expected across portions of eastern OK, southeast KS, southern MO=20
and northern AR. Mid level shortwave energy, favorable upper jet
dynamics and strong low level moisture transport all support an
organized convective risk. Model instability forecasts are
sufficient for deep convection capable of heavy rainfall rates,=20
and PWs of at least 1-2 SD above average are expected. The current=20
model consensus is for the max rainfall axis to stretch from west=20
to east near the AR/MO border. This axis also saw heavy rainfall=20
last night, and could very well see additional areas of heavier=20
rain through Monday. When considering these antecedent conditions,
an upgrade to a MDT risk may be needed on future updates across=20
portions of the area. However, we are still pretty far out, and=20
there remains some latitudinal spread with the heaviest rainfall=20
axis. This event will soon move into the range of more of the high=20
res models, at which point we will likely see some fine tuning and=20
adjusting of the rainfall axis and magnitudes. Thus we will hold=20
off on any upgrade, and still consider this a higher end Slight=20
risk area. Either way would expect at least scattered instances of
flash flooding Tuesday, some of which could be locally considerable.

Chenard

...Previous Discussion...

There continues to be model differences in the evolution of the mid
to upper level trof over the Central to Southern Plains toward the
Mid Mississippi Valley. The NAM continues to be an outlier in being
more amplified and faster to push the height falls downstream.
Despite the differences, models do show re-strengthening of the low
level southwesterly flow ahead of surface low pressure moving east
across Oklahoma into Arkansas. This will support potential for
organized convection, that likely forms late day 2 to the north of
this low across the Central Plains, continuing day 3 from southeast KS/northeast OK, across Southern MO and northern AR. Model
consensus is for the heaviest totals across these areas with
amounts of 2-4" possible. This heavy axis will possibly overlap
where heavy rains have fallen over the past 24 hours and where
additional heavy rains are possible during the day 1 period. There
were no major changes to the slight risk area from the previous
issuance. The marginal risk was extended farther westward into
northeast CO where several models show heavy rain potential day 3.
The eastern portion of the marginal risk was also extended into the
Upper OH Valley to cover the model qpf spread.

...Southern to Central California...
The nearly stationary closed low off the Southern CA coast day 2
will begin to slowly move back to the north on day 3 toward the
Central CA coast. This slow north movement will also allow for a
northward expansion of the anomalous PW values over Southern CA
into Central CA, with values as high as 3-4 standard deviations
above the mean. There are differences with qpf distributions given
differences with the northward push of the closed low. Not a lot
of confidence in any solution at this range, but continued
potential for locally heavy rains and isolated runoff issues,
especially over any burn scars. No changes made at the moment to
the previous broad marginal risk area over Southern to Central CA.

Oravec

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!53vZvBQjfeVOLpokbfnH09UBUnsiIhQycEtcm6bf2K9U= MBmjS7vMUF4hwmskHlj62euYqyxNkTTRnlXgtWTWxmlIigg$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!53vZvBQjfeVOLpokbfnH09UBUnsiIhQycEtcm6bf2K9U= MBmjS7vMUF4hwmskHlj62euYqyxNkTTRnlXgtWTWvkAhyQ4$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!53vZvBQjfeVOLpokbfnH09UBUnsiIhQycEtcm6bf2K9U= MBmjS7vMUF4hwmskHlj62euYqyxNkTTRnlXgtWTWVyGByEs$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 230825
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
425 AM EDT Tue Sep 23 2025

Day 1
Valid 12Z Tue Sep 23 2025 - 12Z Wed Sep 24 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHERN
MISSOURI, FAR SOUTHEAST KANSAS, EASTERN OKLAHOMA, FAR NORTHEAST
TEXAS, ARKANSAS, WESTERN TENNESSEE, WESTERN KENTUCKY, AND SOUTHERN
ILLINOIS AND SOUTHERN INDIANA...

...Lower Arkansas Valley, Lower Mississippi Valley into the Lower
Ohio Valley...

The strengthening low level southerly flow/anomalous 850-700 mb
moisture flux that have supported organized convection over the
Central to Southern Plains early Tuesday will continue to support
the downstream push of this organized convection post 1200 UTC,
with these anomalous 850-700 mb moisture flux values of 2-3+
standard deviations above the mean moving from the eastern sections
of the Southern Plains into the Lower AR Valley, Lower MS, TN and
OH Valleys. There continues to be some north south spread in the
models with respect to the position of the max precip axis.
Generally, the non-CAMs are farther north and the CAMs farther
south. WPC continues to support the farther south qpf solutions,
with our day 1 risk areas drawn toward them. Overall, not a lot of
changes to the previous slight risk areas. We did extend the slight
risk farther east into the Lower OH Valley where there is expected
to be overlap of day 1 heavy precip with observed precip over the
past 24 hours. We also extended the slight risk area farther south
into northeast TX where several of the new 0000 UTC hi-res runs and subsequently the new HREF mean show heavy precip. Otherwise, the
slight and 25% areas fit well with where the HREF and RRFS
neighborhood probabilities are high day 1 for 2" and 3+ amounts.


...Coastal Central California...
There continues to be good model agreement with the nearly
stationary closed low off the Southern CA coast beginning to
slowly move back to the north on day 1 toward the Central CA
coast. This slow north movement will also allow for a northward
expansion of the anomalous PW values over Southern CA into coastal
Central CA, with values as high as 3-4 standard deviations above
the mean. With good model agreement on the closed low track day 1,
there is also good agreement on potential for areal average
moderate precip totals, with potential for locally heavier amount
along the Central CA coast. Isolated runoff issues are possible,
especially over any burn scars.

Oravec

Day 2
Valid 12Z Wed Sep 24 2025 - 12Z Thu Sep 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE
TENNESSEE AND OHIO VALLEY REGIONS...

Anomalous PW and 850-700 moisture flux values will stretch across a
large area from the Lower MS Valley, and into the TN & OH Valleys,
Central Appalachians and the Mid-Atlantic, ahead of the amplifying
longwave trof stretching from the Great Lakes, southward into the
Lower MS Valley. There still is a fair amount of qpf spread with
the max axis day 2. WPC is leaning more toward the multi model
ensemble qpf mean/NBM to drive our qpf and excessive rainfall
axes. This will support a widespread axis of moderate to heavy
precip amounts from eastern TX into the Lower MS Valley, TN and OH
Valleys. While a large portion of the day 2 QPF and ERO axes are
currently in moderate to severe drought, there may be overlap in
qpf areas from day 2 and what has fallen over the past 24 hours
from eastern TN into central to eastern KY, and the Upper OH Valley
region. The previous slight risk was narrowed to better fit this
potential overlap areas. The marginal risk was also trimmed
significantly from southern L.P. of MI, IL, southeast MO and AR to
better fit the latest qpf update.

...Central California...
The slow moving closed low approaching the central CA coast late
day 1 will continue to push slowly eastward day 2 and push inland
by early Thursday morning. Similar to the day 1 period, an axis of
anomalous PW values, 2 to 3 standard deviations above the mean,
will persist to the east northeast of the closed low across Central
CA. Scattered convection in this anomalous PW axis will support
locally heavy rains across Central CA and isolated runoff issues,
especially across burn scar regions.

...Far southeast Arizona into New Mexico...
No changes made to the previous marginal risk area across this
region. Scattered convection possible, with localized heavy rain
and isolated runoff issues, especially in burn scar regions.

Oravec

Day 3
Valid 12Z Thu Sep 25 2025 - 12Z Fri Sep 26 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND FAR SOUTHWEST NEW MEXICO...

The slow moving closed low moving inland into Central CA day 2 will
drop back to the south southeast toward Southern CA day 3. This
system will continue to have an area of anomalous PW values in the
vicinity of the upper center across Central CA into the Great
Basin. This closed low will also begin to tap anomalous PW values
over northwestern Mexico, transporting them into southeast Arizona
day 3. Model consensus is for a max precip area over Southeast
Arizona and far southwest New Mexico. The previous slight risk
across this area was only modified slightly, expanding it slightly
to the north and east to cover the model max qpf spread. Only some
minor changes to the marginal risk to the northwest of this across
northern AZ, southern NV, far southwest UT and into the central
Sierra. Locally heavy rains and isolated runoff issues possible
across these areas, especially over burn scars.

...Southern to Central Appalachians...
There will continue to be a broad axis of above average PW values
pushing eastward day 3 ahead of the elongated upper trof
stretching from the Great Lakes into the OH and TN Valleys. There
is a lot of qpf differences in this high PW axis, leading to low
confidence in where to put risk areas. Much of the eastern U.S. is
in drought conditions with low relative soil moisture levels. One
exception is over portions of the Southern to Central Appalachians
from eastern TN/far western NC/far southwest VA and eastern WV.
Kept the day 3 marginal confined to these areas and removed the
broader marginal from the previous issuance that extended north and
east into the Mid-Atlantic and southwestward to the Gulf Coast.


Oravec

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!8Zu8ZnL1PPrE0Wx6wMUWtfPThSPOny5Dxs22C7qC2cZw= VGe2DnNYUBD8tyXBMSa6eaVoiGaStbv9ULX8CM8LV_WWBhE$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!8Zu8ZnL1PPrE0Wx6wMUWtfPThSPOny5Dxs22C7qC2cZw= VGe2DnNYUBD8tyXBMSa6eaVoiGaStbv9ULX8CM8LDObXeQ4$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!8Zu8ZnL1PPrE0Wx6wMUWtfPThSPOny5Dxs22C7qC2cZw= VGe2DnNYUBD8tyXBMSa6eaVoiGaStbv9ULX8CM8LEHiSYnE$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 040056
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
856 PM EDT Fri Oct 3 2025

Day 1
Valid 01Z Sat Oct 04 2025 - 12Z Sat Oct 04 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
EASTERN FLORIDA AND THE INTERMOUNTAIN WEST...

...Florida's East Coast...

For the 03/01Z Update, made few changes to either Marginal Risk
area. The northern portion of the Marginal Risk area in Florida was
removed for the duration of the overnight hours as drier air
filtered in from the north during the day. The respite should be
short-lived. Farther south...maintained the Marginal Risk area
where the moisture was deeper and radar still showed some showers
and thunderstorms poised to move inland with some potential to
bring brief heavy rainfall to highly urbanized areas in the short=20
term.


Across the West...Late afternoon/early evening water vapor
satellite imagery showed a shortwave trough making its was across
the southern portion of the Marginal risk area. That was helping
focus some generally light showers. Maintained the Marginal risk
area given recent heavy rainfall over portions of the Great Basin=20
will likely have primed surfaces for runoff from additional=20
precipitation. Burn scars continue to be of concern this evening.
Also noted that the 18Z HREF EAS exceedance probabilities continued
to show a low-end risk of 1- and 3-hourly flash flood guidance
being exceeded into the overnight hours over northern/central=20
Nevada where PWATs will be between 2-3 standard deviations above=20
normal.

Bann

Day 2
Valid 12Z Sat Oct 04 2025 - 12Z Sun Oct 05 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
FLORIDA'S EAST COAST...

20Z Update...
The Marginal Risk was removed from southeastern Louisiana.
Consensus of the 12Z HREF and 06Z RRFS showed their higher
probabilities for onshore heavy amounts that are associated with a
slow-moving wave remaining confined to the immediate coast and
away from the more vulnerable I-10 corridor. Should the models
trend back to the north, a Marginal Risk may be reintroduced, but
for now the area has been removed from the outlook.

For the Florida East Coast, the signal for widespread showers and
storms, with locally heavy amounts remain. Models have been
generally trending lighter with their QPF. However, with the HREF
still showing some higher probabilities for amounts over 3 inches,
left the Slight Risk centered along the Space/Treasure coasts in
place for now. Also extended the Marginal Risk further south into
the Miami metro, where the hi-res ensembles also show some higher
for amounts over 3 inches.

Previous Discussion...
...Florida's East Coast...

Thunderstorms are expected to continue to develop along the
inverted trough axis oriented north-south along Florida's east
coast on Saturday. Moisture will lift north along with the mid-
level disturbance. The inherited slight and marginal risk areas
were maintained due to a mostly consistent signal for excessive
rainfall over the east central coast. Ensemble exceedance
probabilities of 2 inches are between 5-10% across the marginal
risk area. 48 hour totals between 3-5 inches (local 6") will likely
make overcoming flash flood guidance a bit easier.


Pereira/Kebede

Day 3
Valid 12Z Sun Oct 05 2025 - 12Z Mon Oct 06 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE CENTRAL GULF COAST AND THE SOUTHEAST COAST...

20Z Update...

No significant changes were made to the previous outlook.

Previous Discussion...
...Central Gulf Coast...

The mid-level disturbance continues propagating westward toward the
positively tilted upper trough centered over the West on Sunday.
Thus, the heavy rainfall threat will likely bleed over from
Saturday evening into Sunday morning for portions of the Central
Gulf Coast, before dissipating beneath diminished support aloft.
PWATs of 2-2.5" and instability between 500-1000 J/Kg MUCAPE could
churn out rain rates between 1-1.5"/hr Saturday morning into
afternoon. Ensemble exceedance probabilities of 2 inches are
between 5-15% along the far southeastern Louisiana to Florida
panhandle corridor, which supports the marginal risk area in
place.

...Southeast Coast...

Inverted troughing continues along the Florida/Southeast Coast
through the latter part of this weekend. Anomalous moisture (2-3
stndv) will continue interacting with the surface boundary to
generate scattered to isolated thunderstorms across the
Florida/Georgia coast. Rainfall totals of 1-3" are likely along
the Florida/Georgia/South Carolina coast on Saturday. The latest
guidance has trended away from tropical moisture making its way
inland, therefore a marginal risk was maintained for much of the
Southeast Coast.


Pereira/Kebede


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!7q1YusVS2TQk_bBeEGA09DfUHFZVKq_Jy_wy8qjwKM0C= z4NJoGOVcYBasMjuB09LIxQl-P64D7tOb09edAZNsIPvlCM$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!7q1YusVS2TQk_bBeEGA09DfUHFZVKq_Jy_wy8qjwKM0C= z4NJoGOVcYBasMjuB09LIxQl-P64D7tOb09edAZNPekqucc$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!7q1YusVS2TQk_bBeEGA09DfUHFZVKq_Jy_wy8qjwKM0C= z4NJoGOVcYBasMjuB09LIxQl-P64D7tOb09edAZNI9JBRVY$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 110040
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
840 PM EDT Wed Sep 10 2025

Day 1
Valid 01Z Thu Sep 11 2025 - 12Z Thu Sep 11 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF=20
THE NORTHWEST AND FLORIDA'S SPACE COAST...


...Florida...
A stationary front draped across the central Florida Peninsula=20
will remain in place as abundant tropical moisture, characterized=20
by PWATs over 2 inches, remains focused in its vicinity. Post-=20
frontal convection is possible late tonight into early tomorrow=20
morning in and near the Space Coast in an area where onshore flow
from the Gulf Stream brings instability to the coast in an=20
environment of slightly cooler air aloft. A short, training band or
two cannot be ruled out, so maintained this small portion of the=20
preexisting Marginal Risk area.


...Pacific Northwest...
A large upper level low and associated trough covering much of the
West Coast will gradually drift east/inland across the Intermountain
West today. Shortwave energy rotating around the low, interacting=20
with the instability caused by the cold air aloft and unusually=20
high amounts of atmospheric moisture (anomalies to 2.5 sigma above=20
normal) has allowed for clusters of showers and a few storms=20
capable of heavy rainfall to form. The 18z HREF suggest that any
heavy rain-related issues over burn scars could persist for another
several hours before fading.

Roth


Day 2
Valid 12Z Thu Sep 11 2025 - 12Z Fri Sep 12 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTH FLORIDA...

...Florida...

21Z update... The latest guidance trended a little drier across
portions of central Florida so the northern boundary of the
Marginal was trimmed southward. Additionally, there was an uptick
in QPF for locations west and southwest of Lake Okeechobee which
prompted a minor westward expansion of the Slight Risk area.
Elsewhere the highlighted level of threat remains appropriate.

Campbell

The stationary front plaguing Florida for well over a week will
begin to move as a cold front on Thursday, as a reinforcing shot of
cooler and drier air pushes south across the Southeast. As the
front pushes south down the Peninsula, the front should act as a
source of forcing for the storms, allowing for greater organization
and greater areal rainfall across South Florida as compared with
previous days when the forcing was far less defined. Add in the
saturated soils across south Florida, and the area where flooding
could be more frequent than isolated instances expands north up the
I-95 corridor towards the advancing front. Thus, the Slight was
expanded north accordingly.

...Pacific Northwest into the Northern Plains...

21Z update... The latest model runs hinted that more QPF would
reach eastern Montana and far northwest North Dakota than some of
the previous cycles. Therefore a portion of the Marginal boundary
was adjusted to include more of/expand into the following counties- Yellows= tone,
Big Horn, Treasure, Rosebud, Custer, Prairie, McCone,
Garfield, Dawson, Richland, Roosevelt, Sheridan, Williams, Divide
and Burke Counties.

Campbell

A plume of anomalously high moisture in place from the Pacific
Northwest to the Northern Plains will support scattered showers and thunderstorms forming once again along a corridor from eastern
Oregon through much of northern Montana. A separate cluster of
storms may sneak south across the Canadian border and into far
northeastern North Dakota and northwestern Minnesota as well. Due
to the potential for heavy rain in all of these areas, a Marginal
Risk is in place and has been expanded eastward to cover the areas
most likely to see isolated instances of flash flooding from heavy
rain from these features.

...Western Colorado and Far Northwestern New Mexico...

Southerly flow on the western edge of a low-level jet across the
Plains will transport Gulf moisture into the region on Thursday.
Meanwhile the large trough out west will become positively tilted
with time. This will allow an 80 kt jet southwesterly jet streak to
form, which will increase the divergence aloft across this area.
Expect upslope into the high peaks of southwestern Colorado to
locally enhance rainfall totals, thereby increasing the flash
flooding risk. Soil moisture measurements from NASA Sport show much
of this area to be below average/drier than normal. Thus, expect
much of the rainfall Thursday in this region to work to saturate
the soils in anticipation of Day 3/Friday's bigger rainfall event.

Wegman

Day 3
Valid 12Z Fri Sep 12 2025 - 12Z Sat Sep 13 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTH FLORIDA AS WELL AS FOR PORTIONS OF NORTHWESTERN NEW MEXICO
INTO SOUTHWESTERN COLORADO...

...Northwestern New Mexico into Southwestern Colorado...

21Z update... In general, the areas highlighted with the Slight and
Marginal Risks for excessive rainfall remain in good order. Minor
reshaping of the Slight was done to reflect latest WPC QPF, noting
that north side was expanded further to include northern Gunnison
and southern Pitkin Counties in the Slight.

Campbell

A positively tilted longwave trough centered over much of the
Intermountain West on Friday will become more neutrally tilted on
Friday as a strong shortwave trough causes the southern half of the
trough to begin to race eastward. The result will be even more
enhanced upper level divergence out ahead of the trough over New
Mexico and Colorado. Atmospheric moisture will be largely unchanged
in this area from Thursday. With peak heating Friday afternoon,
numerous showers and thunderstorms will form over nearly all of the
High Plains. However, coverage and intensity will be much higher
in the Slight Risk area in Colorado and New Mexico. The area is
likely to be the same one hard hit from the Day 2/Thursday period,
so expect soil moisture amounts to be higher and FFGs to be lower
over much of the area by Friday's event. Given all of these
ingredients in place and in coordination with GJT/Grand Junction,
CO forecast office, a Slight Risk upgrade was introduced with this
update.

...South Florida...

21Z update... QPF trended a bit southeast for this period but
still focusing the highest amounts in the Miami-Dade/Broward
vicinity. Western portions of Collier, Hendry, Palm Beach and
Martin Counties were trimmed from the Slight. All or portions of
Sarasota, Charlotte, Manatee, DeSoto, Hardee, Highland, and Polk
were trimmed out of the Marginal, while portions of Osceola and
Brevard were added.

Campbell

The cold front across central Florida at the start of the day
Friday will make slower, but still incremental progress in its
southward movement down the peninsula. The plume of tropical
moisture across south Florida ahead of the front will also still be
in place. Thus, as is similar to Thursday over the middle of the
state, the axis of heaviest moisture will simply shift southward to
far south Florida on Friday. The inherited Slight Risk area was
expanded west over much of the Everglades and portions of southwest
Florida with this update, to follow more closely to where the axis
of heaviest rainfall is likely to set up. Given the focus will
shift into the more vulnerable and flood prone urban areas of south
Florida, its entirely possible that a higher end Slight risk will
need to be issued for the Ft. Lauderdale to Miami corridor with
future updates.

...Northern High Plains...

21Z update... The Marginal Risk area was reshaped across portions
of northeast Wyoming, southeast and northeast Montana, northwest
South Dakota and southwest North Dakota. The latest guidance
trended less wet for portions of western South Dakota, northwest
North Dakota and parts of northeast Montana near the North Dakota
border. However the guidance focused the higher QPF across south
Montana and into the surrounding counties of North Dakota and
South Dakota.

Campbell

Similar to Day 2/Thursday, anomalous moisture will remain in place
across much of Montana and portions of adjacent states again on
Friday. The upper level low and trough will move overhead or just
south of the region on Friday. As the cold air aloft peaks in depth
on Friday, numerous showers and thunderstorms are likely to
redevelop again on Friday afternoon with peak heating and maximum
instability. The axis of heaviest rain from central Idaho through
northwestern Montana will also be largely unchanged and unmoving
from Thursday, meaning these areas will likely have a second day of
showers and storms capable of heavy rain and flooding again on
Friday. Thus, here too a Slight Risk upgrade may be needed with
future updates. This will largely be determined by how much rain
falls on Thursday in this area, which will prime the soils for
Friday's round of rain.

Wegman


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!7nOhw-lypM05lTF1HKK-3FWOInLjw4r--h2Nzetg_1ud= ncwQTtN5TIac2N3tZUijKbc3pq9DX-9DfQMehoKhRGhkBx8$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!7nOhw-lypM05lTF1HKK-3FWOInLjw4r--h2Nzetg_1ud= ncwQTtN5TIac2N3tZUijKbc3pq9DX-9DfQMehoKheUcC1i0$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!7nOhw-lypM05lTF1HKK-3FWOInLjw4r--h2Nzetg_1ud= ncwQTtN5TIac2N3tZUijKbc3pq9DX-9DfQMehoKhVXs-ov8$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 112002
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
402 PM EDT Thu Sep 11 2025

Day 1
Valid 16Z Thu Sep 11 2025 - 12Z Fri Sep 12 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTH FLORIDA...

16Z update... The latest observations and model trends continue to
support an elevated threat for localized excessive rainfall and
areas with flash flooding concerns for Florida, Colorado, New
Mexico, and from the Pacific Northwest across the northern states
to Minnesota. The current Marginal and Slight areas remain
warranted with no changes needed at this time.

Campbell

...South Florida...

A quasi stationary front over central Florida will make incremental
southward progress down the Peninsula today. Ahead of this source
of forcing, atmospheric moisture levels across south Florida remain
very high, with PWATs above 2 inches. With afternoon heating,
MUCAPE levels will once again rise to between 2,000 and 3,000 J/kg.
This will support numerous showers and thunderstorms developing
over the southern half of the state, and generally moving southward
through the afternoon. However, as is typical of Florida afternoon
convection, while the overall storm motion may be southward,
localized forcing such as cold pools and sea breezes may make
individual cell motion far more erratic. Given that soils across
much of the Florida Peninsula are fully saturated after weeks of
afternoon convection each and every day, this will still pose a
widely scattered flash flooding risk, particularly along the urban
I-95 corridor. However, given the saturated soils, the threat
extends into much of interior south Florida as well. The inherited
risk areas were trimmed from the north to eliminate most areas that
are already behind the front, and therefore much drier.

...Northwest...

An area of well above average moisture on the northwestern side of
a nearly stationary longwave trough/cutoff low over the
Intermountain West will act as a focus for additional shower and
thunderstorm activity in the typically dry areas from eastern
Oregon northeast through much of Montana. While the longwave trough
will be very slow-moving, the embedded shortwaves and vort maxes
circulating around it will be faster moving, providing additional
forcing and areas of divergence for any shower and thunderstorm
development. Local mountains and ranges will also work to cause
some thunderstorm development. Thus, due to there being several
forcing mechanisms with little to note as to which will be
dominant, expect multiple clusters of storms to develop this
afternoon with peak heating. With plenty of atmospheric moisture
available for those storms, many may be capable of heavy rainfall
which could quickly cause flash flooding, especially in any urban
areas, slot canyons, and narrow river valleys.

...Western Colorado into Northwestern New Mexico...

On the eastern side of the deep longwave positively tilted trough
in the west, increased divergence and lift ahead of that trough,
supported by southerly flow of moderate amounts of Gulf moisture
will support numerous showers and a few storms forming across the
Marginal Risk area today through tonight. The key to the flooding
potential in this area will be the long duration of mostly light
rain but that will be training in this Marginal Risk area from this
afternoon through much of tonight. The Marginal Risk area remains
largely unchanged from inherited.

Wegman

Day 2
Valid 12Z Fri Sep 12 2025 - 12Z Sat Sep 13 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTH FLORIDA AS WELL AS FOR PORTIONS OF SOUTHWESTERN COLORADO INTO
CENTRAL NEW MEXICO...

...South Florida...

The front across South Florida on Friday will make additional
progress southbound down the Peninsula. The portion moving down the
west coast of the peninsula will make better progress southward
compared to the portion of the front along the East Coast. This
should support the front becoming increasingly aligned southwest to
northeast. Since the front will be moving a bit more on Friday,
there should be a bit better coverage of storms across south
Florida, where the Slight Risk area inherited remains largely
unchanged. As the front pushes south, it will shove the bulk of the
tropical moisture into the Florida Straits and into the Bahamas.
This should work to limit storm coverage on future days, as a much
drier and cooler air mass continues to envelop the rest of the
state.

...New Mexico and Colorado...

21Z update... The environmental setup continues to look rather=20
favorable for heavy rainfall for the higher terrain of Colorado and
New Mexico. The Slight Risk area was reshaped a bit on the eastern
and southern sides across New Mexico to account for the latest WPC
QPF and model trends. The Marginal Risk remained in good order.

Campbell

The positively tilted upper level trough from Thursday will begin
to pivot to become neutrally tilted on Friday. This means the
southern end of the trough will get a boost to advance eastward,
while the northern end will largely stay in place. The result will
be a more south to north oriented axis of heavy rainfall,
stretching from the southern end of New Mexico north across much of
western Colorado. Moisture from the Pacific will also be drawn
northward along the New Mexico/Arizona border. This should expand
the rainfall footprint for Friday across much of the southern
portion of New Mexico and southeastern Arizona. Expect Friday to
the wettest day this week for New Mexico and Colorado.

CAMs guidance suggests the plume of moisture stretching NNE from
southeast Arizona through north-central New Mexico and into
Colorado will be the focus for additional convection capable of
producing flash flooding. With better southward extent, the storms
will be able to tap into some deeper moisture and instability from
the Pacific on Friday. This will make thunderstorm coverage Friday
greater than in previous days. Since the whole plume will also be
lifting north and east, expect a much larger area of rain to impact
the area Friday. Embedded thunderstorms among the mostly lighter
shower activity will be the foci for any potential flash flooding.
This will be particularly true in any areas where multiple rounds
of storms producing heavy rain occur.

...Northwest into Northern High Plains...

21Z update... Still expecting convection to fire up across the
Intermountain West and track eastward into the High Plains during=20
this period. There was a notable uptick in QPF for western portions
of North Dakota, as such, the Marginal Risk was expanded further
into western North Dakota and northwest South Dakota to capture=20
this trend.

Campbell

Shortwaves and vorticity maxes rounding the periphery of the
longwave trough will be the foci causing additional convection from
northern Idaho east across much of Montana. The expected rainfall
forecast has decreased the overall rainfall in this area. However,
mountain forcing may offset this in some areas.

Wegman

Day 3
Valid 12Z Sat Sep 13 2025 - 12Z Sun Sep 14 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM EASTERN NEW
MEXICO THROUGH SOUTHWESTERN KANSAS, AS WELL AS FOR A PORTION OF THE
URBAN CORRIDOR OF SOUTH FLORIDA...

...New Mexico through Kansas...

21Z update... The best focus for heavy rainfall and associated
flash flooding will continue to be across eastern New Mexico,=20
Texas Panhandle and into western Kansas during this period. The=20
Slight Risk was reshaped a little to become more SSW to NNE=20
orientated, rather than SW to NE.

Campbell

As the upper level trough over the Intermountain West becomes more
negatively tilted, a portion of the low level jet out ahead it will
draw deeper Gulf moisture north into the Panhandles and eastern New
Mexico and into southwestern Kansas. This will support a line of
storms that will develop over central New Mexico and then press
eastward into the Slight Risk area. Once over eastern New Mexico
and the Panhandles, the eastward progress of the storms will
diminish greatly, resulting in much slower-moving but still
organized storms. This will be the basis for training, resulting in
widely scattered instances of flash flooding where the storms are
the most persistent.

...South Florida...

The front over South Florida will finally push east and clear all
of the deepest tropical moisture well out into the Atlantic and
Bahamas by Sunday morning. Thus, expect Saturday to be a transition
day in the area...where there will still be storms, particularly
along the urban I-95 corridor from Miami through Palm Beach, but
there will be less coverage over Florida as the moisture is pushed
eastward out into the Atlantic. The newly issued Slight is a low-
confidence one, as once the front clears the state, that should end
the flooding threat. However, given the many days of daily
afternoon convection in the I-95 corridor, soils are sensitive
enough that even the reduced time and coverage of storms could
still cause widely scattered instances of flash flooding.

...Northern Plains...

21Z update... A minor trim was made to the southern bounds across
central South Dakota as the latest guidance suggests QPF may not
advance that far east during this period, thus lowering the threat
for excessive rainfall.

Campbell

Across the Northern Plains, ahead of the neutrally tilted trough
that is becoming negatively tilted, the northern extent of the low
level jet ahead of the trough will draw deeper Gulf moisture
westward across the Dakotas. This should support persistent
convection. However, this area of the Dakotas is fairly difficult
to flood, so despite the higher probability for training and heavy
rain, the area remains in a higher-end Marginal for now. A Slight
Risk upgrade may be needed for portions of the area as guidance
begins to resolve this part of the event across the northern
Plains.

Wegman


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!7D4BL982fsdMXqN9__Q9mqHizp7RhdWPz3EPw4e0OYRs= IqrjLIcF8CfpYXZStydJyOFIX4cOpkxRpz6NE1fVH76yvsE$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!7D4BL982fsdMXqN9__Q9mqHizp7RhdWPz3EPw4e0OYRs= IqrjLIcF8CfpYXZStydJyOFIX4cOpkxRpz6NE1fVWFOwn2w$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!7D4BL982fsdMXqN9__Q9mqHizp7RhdWPz3EPw4e0OYRs= IqrjLIcF8CfpYXZStydJyOFIX4cOpkxRpz6NE1fV4CCkj0I$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 121925
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
325 PM EDT Fri Sep 12 2025

Day 1
Valid 16Z Fri Sep 12 2025 - 12Z Sat Sep 13 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTH FLORIDA, SOUTHWESTERN COLORADO THROUGH CENTRAL NEW MEXICO,
AND THE NORTHERN PLAINS...

...South Florida...

Stationary front persists over far South Florida today with the
positive moisture anomaly focused over the Miami metro with the
eastern coast likely to get more slow moving heavy thunderstorms
in the light mean layer flow. The Slight Risk is shrunk to be
closer to the Miami-Palm Beach metro area with the Marginal Risk
still extending up the east coast nearly to Jacksonville.

...New Mexico and Colorado...

The positively tilted upper level trough from an upper low over
northern NV will pivot to neutral tilt this afternoon. Therefore,
expect a more south to north oriented axis of heavy rainfall,
stretching from south-central New Mexico to across much of western
Colorado. Moisture from the Pacific will also be drawn northward
into eastern Arizona and western New Mexico with PW anomalies of
+1.5 to 2 sigma, resulting in a rather large QPF footprint.
Diurnal convection is the main focus at play today, though
guidance continues to suggest repeating rains over southeast AZ and
southern NM into the overnight. The Slight Risk is maintained over
southwest CO and central NM.

...Northern Rockies onto the Northern Plains...

16Z update... A very small westward expansion of the Slight Risk
was made across southeast Montana to reflect the latest
observations and QPF trends.

Campbell

The upper low center shifts north to MT by late tonight. Notable
activity ahead of the low/trough looks to focus over the western
Dakotas into eastern MT per 00Z CAM consensus where a Slight Risk
has been raised. PW anomalies of 1 to 2 sigma remain over northern
ID/western MT where the Marginal Risk is maintained.

...Upper Midwest...

16Z update... Several inches of rain were reported with the storms overnight/early this morning that are currently tracking across
eastern North Dakota and northern Minnesota. The storms are
straddling the northern boundary of the Marginal Risk and are
increasing the threat for excessive rainfall for areas outside of
the outlook. The northern boundary of the Marginal was lifted
northward to include areas up to the International border of
Minnesota.

Campbell

Ongoing activity over eastern ND and northern MN should shift
southeast by 12Z and track to northern WI. Then diurnally driven
convection looks to cross a similar path. Given the advance of
moisture over the upper ridge axis extending over eastern IA, it
was worth adding a Marginal Risk to northern MN/WI and the western
U.P. of MI.


Jackson


Day 2
Valid 12Z Sat Sep 13 2025 - 12Z Sun Sep 14 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR THE TEXAS AND
OKLAHOMA PANHANDLES INTO EAST NEW MEXICO AND FAR WESTERN TEXAS, AS
WELL AS FOR WESTERN NORTH DAKOTA...

...20z Update...

Some notable changes for this update include:

1) Trimming the northern end of the inherited SLGT risk, as the
most notable signal for convective organization and potential training/repeating exists from eastern NM into the TX/OK Panhandles
(as noted in the previous discussion with the enhancement of the
low-level jet). The MRGL was still maintained into the Central High
Plains, and in fact was generally expanded westward into more of
the Central/Southern Rockies and Intermountain West as anomalous
moisture may be slower to retreat than prior guidance suggested
(based largely on the new 12z CAMs, as well as the character of
convection today being more impressive than models indicated).

2) The removal of the SLGT risk over South FL, as the decreasing
moisture trend noted below is still evident with a notable lowering
of expected QPF based on the new 12z CAMs (which have generally
been too hot in this pattern with convection over South FL to begin
with). The MRGL risk was maintained for any lingering excessive
rainfall threat (and may well be able to be removed early tomorrow).

3) Introduction of a MRGL risk for Chicagoland and surroundings
(southeast WI, northeast IL, much of IN, and far southwest MI).
While the threat for localized flash flooding is conditional, there
is a notable signal from the 12z CAMs suggesting the potential for
3" exceedance (12z HREF 3" exceedance probs of 20-30%) with both
the ARW and ARW2 showing potential for training heavy rainfall (as
well as the NAM-nest, which is the heaviest outlier).

Otherwise, adjusted the SLGT/MRGL borders for the Northern Plains
based on the new guidance.

Churchill


...Previous Discussion...

...Central High Plains through Southern Rockies...

The upper level trough over the Intermountain West becomes
negatively tilted on Saturday with the monsoonal moisture axis over
NM during the day shifting to the southern High Plains overnight.
The position of this trough will enhance the low level jet on the
High Plains Saturday night and draw deeper Gulf moisture north
over the Panhandles and eastern New Mexico and through western
Kansas. This will encourage diurnally developing lines of storms
from New Mexico terrain to press eastward onto the High Plains.
Given the +2 sigma PW anomalies and overall slow storm motion, the
Slight Risk area was expanded a bit over western KS and down into
far western Texas.

...South Florida...

The front will push south from Florida during the day Saturday with
anomalous moisture lingering in the morning over the Miami metro
where A Slight Risk persists. The Slight Risk still looks generous
given the decreasing moisture profile through the day, but is
maintained for now.

...Northern Plains...

The upper low center over central MT will allow the focus for
heavy convection to shift north a bit from Friday with both morning
and diurnal max activity looking to focus on western ND. Given good
overlap in heavier precip among available CAMs and the EC-AIFS, a
Slight Risk is raised over western ND. Pivoting of the low without
much lateral movement is expected, prolonged heavy rainfall is
possible with.

Jackson


Day 3
Valid 12Z Sun Sep 14 2025 - 12Z Mon Sep 15 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL IN THE DAKOTAS...

...20z Update...

Only minor adjustments were necessary based on the new 12z model
suite, as the bulk of the guidance are in good agreement on the
axis of highest QPF.

Churchill


...Previous Discussion...

...Central and Northern Plains...

Negatively-tilted trough axis lifting up the central Plains Sunday
should provide a narrow focus to convective development over the
western or central Dakotas. This activity will be heavy given PW
anomalies of +3 sigma persist over this area. Further development
is expected from central KS up through the Dakotas where a generous
Marginal Risk remains in effect.

Jackson


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!6vltT5ekkXKO5Za2YjghIypKPrsRw8etUrzuCCGsas0i= yw1bzrdUH4e8eDAuzgyHbiR-UimRFasJRFnM_dYX7xzPs-c$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!6vltT5ekkXKO5Za2YjghIypKPrsRw8etUrzuCCGsas0i= yw1bzrdUH4e8eDAuzgyHbiR-UimRFasJRFnM_dYXpmqOO08$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!6vltT5ekkXKO5Za2YjghIypKPrsRw8etUrzuCCGsas0i= yw1bzrdUH4e8eDAuzgyHbiR-UimRFasJRFnM_dYX-BZoqss$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 190811
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
411 AM EDT Fri Sep 19 2025

Day 1
Valid 12Z Fri Sep 19 2025 - 12Z Sat Sep 20 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF THE
CENTRAL SIERRA NEVADA...

...California/Great Basin...

Remnant energy from Mario will continue to lift north across
California and become sheared by an upstream low over the Pacific,
with some energy wrapping back offshore, while the remainder=20
moves east into the Great Basin. This energy, along with highly=20
anomalous moisture (+4 std dev above normal), is expected to=20
continue to produce showers and storms early in the period across=20
parts of California, including the Sierra Nevada. While forecast amounts
have trended down, there is still some signal for locally heavy=20
rain to continue early in the period across portions of the central
Sierra Nevada. A small Slight Risk was maintained, mostly for the=20
initial 6-hours, where the HREF shows higher probabilities for=20
additional amounts exceeding an inch. By the afternoon, as the mid=20
level energy and greater moisture anomalies move east, expect the=20
greater chance for heavier rain to begin to focus over central=20
Nevada, where the HREF is showing a broader footprint of high=20
probabilities for amounts over an inch.

...Southwest...

Expect widespread coverage of showers and storms today, as moisture
from Mario bolsters PWs across the region. The general consensus of
the CAMs show greater coverage across eastern Arizona and western
New Mexico during the afternoon, before storms move southeast into
southeastern New Mexico and West Texas by this evening. Storm=20
motions are expected to generally progressive, limiting the threat=20
for widespread heavy amounts and flooding. However, there is some=20
signal for backbuilding and training, which could raise at least=20
isolated runoff concerns. HREF neighborhood probabilities for
amounts exceeding an inch are above 50 percent within much of the
Marginal Risk area.

...Upper Mississippi Valley/Midwest to the Lower Missouri Valley...

A mid-to-upper level low/negatively-tilted upper trough will
continue to move slowly east from the northern Plains into the=20
upper Mississippi Valley this period. While not expected to be a=20
widespread heavy rainfall event, south-to-north training storms=20
ahead of the associated occluded front, may produce locally heavy=20
amounts and isolated flooding from northern Illinois back across=20
the upper Mississippi Valley. The HREF shows widespread high
probabilities for amounts exceeding an inch across this region,=20
with some localized high probabilities for amounts over two inches.

Meanwhile, shortwave energy diving southeast out of the northern
High Plains, is expected to produce a secondary area of organized
amounts, with some locally heavy amounts possible from=20
southeastern Nebraska into southwestern Iowa and northwestern=20
Missouri this evening into the overnight. Here also, the HREF is
showing high probabilities for amounts over an inch, with heavier
amounts possible.

...Central Plains...

Energy moving through the base of the previously noted upper
trough, interacting with deepening moisture along a strengthening
low level jet is expected produce showers and storms developing=20
and dropping southeast across Kansas, with locally heavy amounts=20
possible by this evening. HREF probabilities indicate localized
amounts of an inch or more are likely, with heavier amounts
possible.

Pereira

Day 2
Valid 12Z Sat Sep 20 2025 - 12Z Sun Sep 21 2025


...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF SOUTHEASTERN KANSAS AND NORTHEASTERN OKLAHOMA THROUGH THE
OZARKS...

Storms developing late in the previous period across Kansas may
continue, producing locally heavy amounts across portions of the=20
Ozark Region Sunday morning. Redevelopment is possible back to the
west later in the day as shortwave energy emanating from the west
moves into the region and interacts with deepening moisture
afforded by strengthening southerly flow.

Pereira

Day 3
Valid 12Z Sun Sep 21 2025 - 12Z Mon Sep 22 2025


...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE SOUTHWEST AND FROM THE OZARKS THROUGH THE MID MISSISSIPPI
VALLEY...

...The Southwest...

An upper low off of the California coast will drift southeast,
supporting the return of deeper moisture spreading north across
Arizona and western New Mexico on Sunday. With PW anomalies
increasing to 2-3 standard deviations above normal, numerous showers
and storms, producing locally heavy rainfall amounts and isolated=20
flooding concerns, can be expected.

...Ozarks through the Mid Mississippi Valley...

A broad upper trough will drift slowly east from the Plains into
the Mississippi Valley this period. A series of mid level
shortwaves lifting along the leading edge of the trough,
interacting an axis of deeper moisture is expected to produce showers
and storms with periods of heavy rainfall possible.

Pereira


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!5sWY6jErU7QoE7Q0X2MAV28jb7Bgyp9K1QGbaPKkKA6n= 3f-m0xhxB8KIqr6FT9W7S2iWEguIQjY9JjqpjGciHnRo0dk$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!5sWY6jErU7QoE7Q0X2MAV28jb7Bgyp9K1QGbaPKkKA6n= 3f-m0xhxB8KIqr6FT9W7S2iWEguIQjY9JjqpjGcidV6JfkU$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!5sWY6jErU7QoE7Q0X2MAV28jb7Bgyp9K1QGbaPKkKA6n= 3f-m0xhxB8KIqr6FT9W7S2iWEguIQjY9JjqpjGcio19ZX4A$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 231953
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
353 PM EDT Tue Sep 23 2025

Day 1
Valid 16Z Tue Sep 23 2025 - 12Z Wed Sep 24 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHERN
MISSOURI, FAR SOUTHEAST KANSAS, EASTERN OKLAHOMA, FAR NORTHEAST
TEXAS, ARKANSAS, WESTERN TENNESSEE, WESTERN KENTUCKY, AND SOUTHERN
ILLINOIS AND SOUTHERN INDIANA...

...Lower Arkansas Valley, Lower Mississippi Valley into the Lower
Ohio Valley...

16Z Update: No significant changes to the risk areas with the main
area of concern being southern Missouri, northern Arkansas, eastern
Oklahoma, and far southeast Kansas where a frontal boundary draped
across interacts with copious amounts of moisture. The 12Z HREF
probabilities align fairly well with the inherited Slight Risk
area with only minimal adjustments needed.

---previous discussion---

The strengthening low level southerly flow/anomalous 850-700 mb
moisture flux that have supported organized convection over the
Central to Southern Plains early Tuesday will continue to support
the downstream push of this organized convection post 1200 UTC,
with these anomalous 850-700 mb moisture flux values of 2-3+
standard deviations above the mean moving from the eastern sections
of the Southern Plains into the Lower AR Valley, Lower MS, TN and
OH Valleys. There continues to be some north south spread in the
models with respect to the position of the max precip axis.
Generally, the non-CAMs are farther north and the CAMs farther
south. WPC continues to support the farther south qpf solutions,
with our day 1 risk areas drawn toward them. Overall, not a lot of
changes to the previous slight risk areas. We did extend the slight
risk farther east into the Lower OH Valley where there is expected
to be overlap of day 1 heavy precip with observed precip over the
past 24 hours. We also extended the slight risk area farther south
into northeast TX where several of the new 0000 UTC hi-res runs and subsequently the new HREF mean show heavy precip. Otherwise, the
slight and 25% areas fit well with where the HREF and RRFS
neighborhood probabilities are high day 1 for 2" and 3+ amounts.


...Coastal Central California...
There continues to be good model agreement with the nearly
stationary closed low off the Southern CA coast beginning to
slowly move back to the north on day 1 toward the Central CA
coast. This slow north movement will also allow for a northward
expansion of the anomalous PW values over Southern CA into coastal
Central CA, with values as high as 3-4 standard deviations above
the mean. With good model agreement on the closed low track day 1,
there is also good agreement on potential for areal average
moderate precip totals, with potential for locally heavier amount
along the Central CA coast. Isolated runoff issues are possible,
especially over any burn scars.

...New Mexico...
The combination of upper level divergence bringing large scale
forcing for ascent along with an axis of slightly above normal
moisture will bring the threat of isolated to scattered
thunderstorms to the area. A Marginal Risk was introduced for the
threat of isolated flash flooding, particularly over any sensitive
areas like recent burn scars.

Oravec/Taylor

Day 2
Valid 12Z Wed Sep 24 2025 - 12Z Thu Sep 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE
TENNESSEE AND OHIO VALLEY REGIONS...

20Z Update:=20
No significant adjustments made to this update with the greatest
threat of intense rain rates and repeated rounds of thunderstorms
over the TN and OH Valleys into portions of the central
Appalachians. Other areas with locally higher rainfall and rain
rates are across portions of northern NJ, eastern PA, and southern
NY late in the period and then across portions of eastern TX as the
convective complexes shift southward.=20

---previous discussion---

Anomalous PW and 850-700 moisture flux values will stretch across=20
a large area from the Lower MS Valley, and into the TN & OH=20
Valleys, Central Appalachians and the Mid- Atlantic, ahead of the=20
amplifying longwave trof stretching from the Great Lakes, southward
into the Lower MS Valley. There still is a fair amount of qpf=20
spread with the max axis day 2. WPC is leaning more toward the=20
multi model ensemble qpf mean/NBM to drive our qpf and excessive=20
rainfall axes. This will support a widespread axis of moderate to=20
heavy precip amounts from eastern TX into the Lower MS Valley, TN=20
and OH Valleys. While a large portion of the day 2 QPF and ERO axes
are currently in moderate to severe drought, there may be overlap=20
in qpf areas from day 2 and what has fallen over the past 24 hours=20
from eastern TN into central to eastern KY, and the Upper OH Valley
region. The previous slight risk was narrowed to better fit this=20
potential overlap areas. The marginal risk was also trimmed=20
significantly from southern L.P. of MI, IL, southeast MO and AR to=20
better fit the latest qpf update.

...Central California...
The slow moving closed low approaching the central CA coast late
day 1 will continue to push slowly eastward day 2 and push inland
by early Thursday morning. Similar to the day 1 period, an axis of
anomalous PW values, 2 to 3 standard deviations above the mean,
will persist to the east northeast of the closed low across Central
CA. Scattered convection in this anomalous PW axis will support
locally heavy rains across Central CA and isolated runoff issues,
especially across burn scar regions.

...Far southeast Arizona into New Mexico...
No changes made to the previous marginal risk area across this
region. Scattered convection possible, with localized heavy rain
and isolated runoff issues, especially in burn scar regions.

Oravec

Day 3
Valid 12Z Thu Sep 25 2025 - 12Z Fri Sep 26 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND FAR SOUTHWEST NEW MEXICO...

The slow moving closed low moving inland into Central CA day 2 will
drop back to the south southeast toward Southern CA day 3. This
system will continue to have an area of anomalous PW values in the
vicinity of the upper center across Central CA into the Great
Basin. This closed low will also begin to tap anomalous PW values
over northwestern Mexico, transporting them into southeast Arizona
day 3. Model consensus is for a max precip area over Southeast
Arizona and far southwest New Mexico. The previous slight risk
across this area was only modified slightly, expanding it slightly
to the north and east to cover the model max qpf spread. Only some
minor changes to the marginal risk to the northwest of this across
northern AZ, southern NV, far southwest UT and into the central
Sierra. Locally heavy rains and isolated runoff issues possible
across these areas, especially over burn scars.

...Southern to Central Appalachians...
There will continue to be a broad axis of above average PW values
pushing eastward day 3 ahead of the elongated upper trof
stretching from the Great Lakes into the OH and TN Valleys. There
is a lot of qpf differences in this high PW axis, leading to low
confidence in where to put risk areas. Much of the eastern U.S. is
in drought conditions with low relative soil moisture levels. One
exception is over portions of the Southern to Central Appalachians
from eastern TN/far western NC/far southwest VA and eastern WV.
Kept the day 3 marginal confined to these areas and removed the
broader marginal from the previous issuance that extended north and
east into the Mid-Atlantic and southwestward to the Gulf Coast.


Oravec

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!45wsvkduC9LWxSdoGKkG5ccYyRNDwsbzD6jV44zf-p3W= rAmQ35ZQu2rsK6Fqo8wGVTKE0sj8OdXIV4zXuPPZVEQIqU4$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!45wsvkduC9LWxSdoGKkG5ccYyRNDwsbzD6jV44zf-p3W= rAmQ35ZQu2rsK6Fqo8wGVTKE0sj8OdXIV4zXuPPZhs_YKNQ$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!45wsvkduC9LWxSdoGKkG5ccYyRNDwsbzD6jV44zf-p3W= rAmQ35ZQu2rsK6Fqo8wGVTKE0sj8OdXIV4zXuPPZLvB3kc4$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 281556
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1156 AM EDT Sun Sep 28 2025

Day 1
Valid 12Z Sun Sep 28 2025 - 12Z Mon Sep 29 2025

...THERE'S A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS MUCH OF NEW
MEXICO AND PORTIONS OF FAR WESTERN TEXAS/SOUTHERN COLORADO, AS WELL
AS, PORTIONS OF NORTHWEST ARIZONA...

16z update:
New Mexico/West TX Panhandle: Mid-level sub-tropical moisture=20
continues to stream northward through the leading height-=20
falls/outer edge of deep-layer cyclone across Western TX Panhandle=20
through the Sacramento Mountains and points northward. Reinforcing=20
surface to boundary layer moisture return through up- slope process
will maintain 1-1.25" total PWats. Embedded mid-level impulses=20
through the large base of the cyclone will allow for multiple=20
rounds across S NM/W TX Panhandle to maintain the Slight Risk.=20

Southwest (N AZ): Near the northwest edge of the inner core of the
upper- low in NW AZ, there remains a slightly enhanced signal for=20
increased rainfall rates/totals per HREF probs and 12z Hi-Res CAMs.
Enough so to be highlighted with 20-40% of 2"+ through 12z . Given
slow cell motions and position relative to the deeper cyclone and=20
fairly saturated soils over the last few days is sufficient to=20
highlight a small separate Slight Risk area.=20

Further North (ID/WY): A subtle vorticity center is lifting north=20
through the northern Great Basin toward the Snake River Plain; Hi-
Res CAMs indicate slightly better instability from 250-500 J/kg may
allow for scattered mountain anchored convection through the
afternoon/evening trending northward toward Tetons and Ranges=20
across SE ID/far W WY. Enough so, to expand the Marginal Risk=20
northward to encompass the increase in potential.=20

Southeast: Forecast remains on track, solid onshore flow and
enhanced deep layer moisture values over 2-2.25 and some weak
500-1000 J/kg of CAPE should allow for scattered thunderstorm
activity capable of locally intense rates. Only minor adjustments
were made to the Marginal Risk line.=20

Gallina

~~~~Prior Discussion~~~~~

...Four Corners/Southwest...
An upper trough centered over the Southwest will continue
directing mid-level vortices northward through the Four Corners
region today. Moisture from Tropical Cyclone Narda in the East
Pacific will continue surging north into the Four Corners, where
scattered showers and thunderstorms are likely to proliferate throughout
the day. PWATs between 1-1.5 inches within the right entrance
region of the upper jet and modest instability around 500-1000+
J/Kg (MLCAPE) could yield rain rates between 0.5-1 in./hr.,
especially where the slight risk is currently drawn. Burn scars,
scars slot canyons and upslope areas within the risk areas are
especially vulnerable to flash flooding.

HREF's neighborhood exceedance probabilities of 2 in. in 24 hours
are between 25-50% while EAS probabilities of exceeding 0.5 in.
hover around 20-40% within the depicted slight risk area.


...Southeast...
An upper trough will pivot eastward over the Southeast while
moisture from T.C. Nine continues surging northward toward the
Southeast Coast. Current guidance keeps the axis of heaviest QPF
offshore, but enough moisture may propagate far enough north and
west to interact with a surface front draped along the coast and
produce localized excessive rainfall. HREF EAS exceedance
probabilities of 1 inch in 24 hours are between 5-15% along much
of the Carolina Coast today, which supports the marginal risk area
depicted.

Kebede

Day 2
Valid 12Z Mon Sep 29 2025 - 12Z Tue Sep 30 2025

...THERE'S A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
CAROLINA COAST...

...Southeast...
Guidance continue to depict T.C. Nine propagating north toward the
Southeast Coast on Monday, while a surface front draped along the
coast acts as the focus for heavy rainfall. QPF has trended
downward given slowing trends in the track of T.C. Nine on Monday.
The GFS suite in particular diverges most from the Canadian and
Euro suites when depicting the system's slower forward motion.
Despite this, enough moisture should work its way into the coast
and interact with the surface front to generate scattered thunderstorms. There'll be enough moisture (1.5-2.5in PWATs) and instability
(1000+ J/KG MUCAPE) present to support rainfall rates in excess of
1 in./hr..

...Northern California/Great Basin/Southern Cascades...
An upper low centered over the East Pacific will send mid-level
vortices into the West Coast on Monday. Pacific moisture may
collide with the remnant tropical moisture from Narda to produce
heavy rainfall from northern California into the Great Basin.
Synoptic forcing provided by a strong surface cold front should
focus PWATs in the range of 0.75-1.25 in. to produce quarter inch
rain rates along the immediate coast. More robust instability over
the Great Basin should yield higher rain rates between 0.5-1
in./hr. in some areas. Upslope enhancement may generate higher
totals in parts of the terrain.

Kebede

Day 3
Valid 12Z Tue Sep 30 2025 - 12Z Wed Oct 01 2025

...THERE'S A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
CAROLINA COAST...

...Southeast...
The inherited marginal and slight risk areas along the Southeast
Coast were downsized based on trends in the guidance suggesting
T.C. Nine's hard turn out to sea on Tuesday. Despite the resulting
smaller QPF footprint than previous cycles, the flash flood risk
remains. Instability will be negligible (less than 500 J/Kg
MUCAPE), which supports the possibility that the flood threat will be
due to runoff over saturated soils from Sunday and Monday's
rainfall. Exceedance probabilities of over 2 inches is over 10% in
the 00z ECENS/CMCE, while below 10% in the GEFS along the
immediate Carolina Coast.

Kebede


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!6uFAzqYdJ_L88XfT5_yzene3C0vAwFQe-dS9asUoHY2O= tb-02gXBFHsvM_b7AEC68SWxmlR637fniM7cMsFfXBYWidY$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!6uFAzqYdJ_L88XfT5_yzene3C0vAwFQe-dS9asUoHY2O= tb-02gXBFHsvM_b7AEC68SWxmlR637fniM7cMsFfs82RwyM$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!6uFAzqYdJ_L88XfT5_yzene3C0vAwFQe-dS9asUoHY2O= tb-02gXBFHsvM_b7AEC68SWxmlR637fniM7cMsFfIs1Rpx0$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 300057
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
857 PM EDT Mon Sep 29 2025

Day 1
Valid 01Z Tue Sep 30 2025 - 12Z Tue Sep 30 2025

...THERE ARE MARGINAL RISKS OF EXCESSIVE RAINFALL FOR PORTIONS OF
NORTHERN CALIFORNIA, SOUTHWESTERN OREGON, THE GREAT BASIN AND
COASTAL NORTH CAROLINA...

...West...
Showers and thunderstorms will continue to move across portions of
NV and ID tonight. Not a lot of instability to work with, and cells
are quick moving...thus it seems unlikely we will get high enough=20
rainfall rates to cause too much of a flash flood concern. However=20
looks like decent coverage of 0.5" to 1" rainfall, with amounts=20
locally exceeding 1". Thus we will maintain the Marginal risk as a=20
very localized flash flood risk can not be ruled out. Also will=20
need to keep an eye on the northern Sacramento Valley north of=20
Redding. Recent HRRR runs indicate the potential for slow moving=20
convection where low level flow locally enhances convergence in the
terrain.

...Southeast...
A Marginal risk was maintained for coastal areas of NC. Moisture=20
well to the north of Imelda will continue to interact with the=20
frontal boundary near the coast producing areas of showers and=20
locally embedded heavier convection. Still looks like most of the=20
higher rates will remain offshore overnight, but a few heavier=20
cells may continue to move into the immediate coast. Overall the=20
flash flood risk is low, but can not rule out a very localized=20
issue along areas of coastal NC, where upwards of 2-4" of rain has
fallen over the past 24 hours. Elsewhere over the Southeast the
higher rates are expected to stay offshore, with just some showery
conditions continuing which is unlikely to produce flash flooding.

Chenard


Day 2
Valid 12Z Tue Sep 30 2025 - 12Z Wed Oct 01 2025

...THERE'S A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE GREAT BASIN AND NORTHERN ROCKIES & OLYMPIC PENINSULA...

21z update...

...Great Basin...
12z Hi-Res CAMs/HREF and global guidance continue a slightly more
progressive solutions with respect to the timing of the cold front
and therefore the moisture flux convergence through the Great Basin
resulting in a slight southeastward expansion of the Day 2 Marginal
Risk across east-central NV and portions of west-central UT. Narrow
streets of training convection within this anomalous moisture
stream with modest remaining instability may result in spots of
.5-1.25" in 1-3 hours, mainly early in the period. Naturally lower
FFG values would suggest scattered incident or two of localized
flash flooding may result, especially along the upwind edge of the
longer overall Marginal area, where backbuilding may be more
likely.

...Olympic Peninsula...
Second and slightly stronger warm conveyor belt increases moisture
flux out of the northeast Pacific. Deep moisture plume of greater
than 1" total PWat, but may tick up to 1.25" will be advected on
mainly southerly flow. Given the oblique nature to the Coastal
Range, mainly the upslope and highest IVT values (peaking around
600-700 kg/m/s) will intersect the SW facing topography of the
Olympic Range. A narrow drying period will likely exist after 00z
toward 06-09z, before the eastern edge of the strengthening core to
the closed low approaches toward the end of the forecast period,
01.12z. HREF probability over 50% of 3"/24hrs exists while a few
Hi- Res guidance members tickle the potential of 5"/24hrs (15-20%
for HREF) across the range. Combined with rain on Day 1, and
continuing into Day 3, felt it appropriate given totals to have a
low potential of exceedance worthy of a Marginal Risk, matching up
with the inherited Day 3 Marginal.

Gallina

~~~~Prior Discussion~~~~
The marginal risk area inherited from the previous cycle was
mostly maintained with an expansion south into central Utah due to
trends in the guidance. The cold front responsible for heavy
rainfall potential in northern California on Monday will propagate
through the Great Basin and Northern Rockies on Tuesday, focusing
additional instability and moisture along its convergence zone.
Ensemble exceedance probabilities of 0.5 inches in 24 hours are
between 5-25% over parts of northeastern Nevada, northern Utah,
southeastern Idaho and western Wyoming. The progressive nature of
the front should mitigate flash flooding concerns.

Kebede

Day 3
Valid 12Z Wed Oct 01 2025 - 12Z Thu Oct 02 2025

...THERE'S A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE OLYMPIC PENINSULA...

21z update...
No change to the placement of the Day 3 Marginal Risk area, though
12z global guidance is showing a slight uptick in strength of CAA
aloft allowing for 250-500 J/kg of elevated CAPE. The overall deep
layer moisture reduces toward .75" but with prolonged southerly
flow of 30-40kts, IVT values are persistent around 300-450 kg/m/s
nearly the entire 24hr period. So consistent light to moderate
upslope rains will have occasional, short duration bursts of
localized convective cores that will add to saturating soils over
the prolonged 3 day event. An additional 2-4" seems likely, but
given scattered convective nature, will be interesting to see any
localized enhanced totals as we move toward the full Hi-Res CAM
window, but end of 12z NAM-Nest and GEM Regional already hint at
slightly higher values...pretty good for an Atmospheric River
season "opener".

Gallina

~~~~Prior Discussion~~~~
A shortwave propagating through the southern periphery of the Gulf
of Alaska low will phase with it and move just off of the British
Columbia Coast by Wednesday. This new system will send a cold front
into the Pacific Northwest. The proximity of the upper low and
associated vorticity lobes should destabilize the environment
(100-300 J/Kg MUCAPE) enough to support isolated thunderstorm
activity. Favorable RER dynamics and mid- level moisture advection
should support efficient rain rates especially over the Olympic
Mountains. ECENS 24 hour exceedance probabilities of 2 inches is
between 20-40% for much of the area.

Kebede


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!_eS4alwTQPGfJTYKCe9UlUvtB1Er220Iz0r5jfZhpnJ_= DNStGZglIJc3qHTsDLyjiachyN5L_CJcaWC7rAamV1fwndA$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!_eS4alwTQPGfJTYKCe9UlUvtB1Er220Iz0r5jfZhpnJ_= DNStGZglIJc3qHTsDLyjiachyN5L_CJcaWC7rAamT4LxE7c$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!_eS4alwTQPGfJTYKCe9UlUvtB1Er220Iz0r5jfZhpnJ_= DNStGZglIJc3qHTsDLyjiachyN5L_CJcaWC7rAam8J--Tes$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 021544
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1144 AM EDT Thu Oct 2 2025

Day 1
Valid 16Z Thu Oct 02 2025 - 12Z Fri Oct 03 2025

...THERE'S A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE SIERRA, GREAT BASIN AND EASTERN FLORIDA...

16Z Update: The previous forecast has not changed much in the
overall synoptic and mesoscale expectations over the two risk areas outlined.=20

Across FL, locally heavy rainfall within the confines of
a surface trough axis aligned parallel, just inland from the
coastal plain will be the threat through the period with urban
flash flooding the most likely case of any potential. Highest 5"
probs via 12z HREF neighborhood output are still in that 40-90%
range, however the highest probs are centered between Melbourne to
West Palm Beach with a centroid near Port St Lucie. This is hi-res
indications of where they anticipate the strongest low-level
convergence regime with relevant moisture flux situated just off
the Atlantic coast at similar latitude to the elevated probs.
Considering some error in convective placement, it's still
reasonable to consider areas from Miami up to Daytona within the
proxy for locally enhanced rainfall rates with hourly rates ~3"/hr
at peak intensity when you factor PWATs hovering between 1.75-2"=20
as of the 10/12z RAOB soundings from Cape Canaveral. This signal=20
in the means and individual deterministic is more than sufficient=20
for a maintenance of the MRGL risk in place with only a minor=20
northward expansion in the area to cover for the current radar
trends.=20

Across the west, the setup remains consistent among all the CAMs
and global deterministic with a relative max situated over the
northern Sierra along and near I-80 where modest instability and
sufficient large scale ascent should initiate a period of moderate
to heavy rain for multiple hours that could enhance a localized
flood prospect. As we move further inland into the Great Basin, the
setup shifts to more scattered/widespread convective schemes that
are better suited for those highly localized flash flood concerns
within topography that historically favors flashier output due to
the soil composition and prevalence of dry washes and arroyos
littered over the high desert. This threat expands into the Snake
River basin of ID and adjacent zones later this evening. Totals
between 1-2" (Locally higher in the northern Sierra) will be most=20
common in the MRGL risk in place from the Central Valley of=20
California up into Sawtooth and Salmon River Ranges of Idaho.=20

Kleebauer

..Previous Discussions..

...Sierra/Great Basin...

An upper low will dig into the West Coast while sending streams of
vorticity into the Sierra Nevada, Great Basin and Northern=20
Rockies. Diffluence will spread across the aforementioned areas=20
throughout the day on Friday. At the surface, a low pressure system
will propagate across the interior West, while anomalous moisture=20
(3-4 stndv PWATs) streams in behind the preceding cold front.=20
Scattered to isolated thunderstorms may develop and produce=20
isolated instances of excessive rainfall and flash flooding.

Upslope enhancement across the Sierra could produce heavier
rainfall totals than what are currently forecast. EAS probabilities
of 24 hour qpf exceeding 1 inch are over 40% in the Sierra and
between 15-40% in the Great Basin. Therefore, burn scars over
central and southern Idaho are at risk of flash flooding today.

...Eastern Florida...

Moist easterly flow into a surface front oriented north-south will
produce scattered convection across Florida today. The surface
boundary draped along the eastern coast will focus PWATs of around
2" in that area where MUCAPE between 500-1000 J/Kg will also likely
produce high rain rates. Neighborhood probabilities of exceeding
5" in 24 hours are between 40-90% from near Miami metro up through
Melbourne and Orlando.

Kebede


Day 2
Valid 12Z Fri Oct 03 2025 - 12Z Sat Oct 04 2025

...THERE'S A MARGINAL RISK FOR PORTIONS OF THE GREAT BASIN AND
EASTERN FLORIDA...

...Great Basin...
The upper trough propagates through the Great Basin and begins
lifting north on Friday. The excessive rainfall threat bleeds into
Friday from Thursday as thunderstorms weaken and spread from the
Great Basin into the Northern Rockies by Friday afternoon. Instability
and moisture will be relatively modest (100-200 J/Kg MUCAPE)
(0.5-0.9"). Ensemble exceedance probabilities of 1" are between
10-20% over northern Nevada with 2 day totals potentially eclipsing
2" in some places.

...Eastern Florida...
Moisture advection into Florida increases on Friday as a mid-level
circulation embedded within a broader upper ridge continues to
direct moisture and instability into the state's east coast.
Another inverted surface trough may develop along the state's east
coast and focus convection along the convergence zone. Ensemble
exceedance probabilities of 2" are between 5-15% along the
immediate coast, while first guess fields support the marginal with
5% flash flood probabilities.


Kebede

Day 3
Valid 12Z Sat Oct 04 2025 - 12Z Sun Oct 05 2025

...THERE'S A MARGINAL RISK FOR PORTIONS OF SOUTHEAST LOUISIANA AND
EASTERN FLORIDA INTO FAR SOUTHEASTERN GEORGIA...

...Central Gulf Coast...
Mid-level vorticity swirling over the Central Gulf Coast will
generate instability and pull an increasing amount of Gulf
moisture into the region on Saturday. Convection should fire along
a coastal convergence zone that develops and diurnal heating should
enhance afternoon/evening storms along that boundary. PWATs will
likely be over 2" with MUCAPE between 500-750 J/Kg. Ensemble exceedance probabilities of 2" are between 15-30% for much of southeast
Louisiana.

...Eastern Florida/Southeastern Georgia...
Tropical moisture associated with Imelda will continue flowing into
Florida due to and upper ridge over the East Coast and embedded
troughing over Florida and the Gulf. A modest instability plume
should flow up the Florida Peninsula into far southeastern Georgia
where PWAT's of over 2" and an inverted surface trough could
combine to produce thunderstorms capable of generating 0.75-1"/hr
rain rates. Ensemble exceedance probabilities of 2" are between
5-15% along Florida's east coast into southeastern Georgia.


Kebede


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!-TXaeIF6zJASOo8o2ZPRpSFXhdz9pbtfYb8Itozk9Wpn= YeHxPDMCzMp2yhoxlB8WXE2lf0pHGWzQUj--paKEvEq-Ky4$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!-TXaeIF6zJASOo8o2ZPRpSFXhdz9pbtfYb8Itozk9Wpn= YeHxPDMCzMp2yhoxlB8WXE2lf0pHGWzQUj--paKEeqNXeZE$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!-TXaeIF6zJASOo8o2ZPRpSFXhdz9pbtfYb8Itozk9Wpn= YeHxPDMCzMp2yhoxlB8WXE2lf0pHGWzQUj--paKEnyhorn4$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 111546
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1146 AM EDT Thu Sep 11 2025

Day 1
Valid 16Z Thu Sep 11 2025 - 12Z Fri Sep 12 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTH FLORIDA...

16Z update... The latest observations and model trends continue to
support an elevated threat for localized excessive rainfall and
areas with flash flooding concerns for Florida, Colorado, New
Mexico, and from the Pacific Northwest across the northern states
to Minnesota. The current Marginal and Slight areas remain
warranted with no changes needed at this time.

Campbell

...South Florida...

A quasi stationary front over central Florida will make incremental
southward progress down the Peninsula today. Ahead of this source
of forcing, atmospheric moisture levels across south Florida remain
very high, with PWATs above 2 inches. With afternoon heating,
MUCAPE levels will once again rise to between 2,000 and 3,000 J/kg.
This will support numerous showers and thunderstorms developing
over the southern half of the state, and generally moving southward
through the afternoon. However, as is typical of Florida afternoon
convection, while the overall storm motion may be southward,
localized forcing such as cold pools and sea breezes may make
individual cell motion far more erratic. Given that soils across
much of the Florida Peninsula are fully saturated after weeks of
afternoon convection each and every day, this will still pose a
widely scattered flash flooding risk, particularly along the urban
I-95 corridor. However, given the saturated soils, the threat
extends into much of interior south Florida as well. The inherited
risk areas were trimmed from the north to eliminate most areas that
are already behind the front, and therefore much drier.

...Northwest...

An area of well above average moisture on the northwestern side of
a nearly stationary longwave trough/cutoff low over the
Intermountain West will act as a focus for additional shower and
thunderstorm activity in the typically dry areas from eastern
Oregon northeast through much of Montana. While the longwave trough
will be very slow-moving, the embedded shortwaves and vort maxes
circulating around it will be faster moving, providing additional
forcing and areas of divergence for any shower and thunderstorm
development. Local mountains and ranges will also work to cause
some thunderstorm development. Thus, due to there being several
forcing mechanisms with little to note as to which will be
dominant, expect multiple clusters of storms to develop this
afternoon with peak heating. With plenty of atmospheric moisture
available for those storms, many may be capable of heavy rainfall
which could quickly cause flash flooding, especially in any urban
areas, slot canyons, and narrow river valleys.

...Western Colorado into Northwestern New Mexico...

On the eastern side of the deep longwave positively tilted trough
in the west, increased divergence and lift ahead of that trough,
supported by southerly flow of moderate amounts of Gulf moisture
will support numerous showers and a few storms forming across the
Marginal Risk area today through tonight. The key to the flooding
potential in this area will be the long duration of mostly light
rain but that will be training in this Marginal Risk area from this
afternoon through much of tonight. The Marginal Risk area remains
largely unchanged from inherited.

Wegman

Day 2
Valid 12Z Fri Sep 12 2025 - 12Z Sat Sep 13 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTH FLORIDA AS WELL AS FOR PORTIONS OF SOUTHWESTERN COLORADO INTO
CENTRAL NEW MEXICO...

...South Florida...

The front across South Florida on Friday will make additional
progress southbound down the Peninsula. The portion moving down the
west coast of the peninsula will make better progress southward
compared to the portion of the front along the East Coast. This
should support the front becoming increasingly aligned southwest to
northeast. Since the front will be moving a bit more on Friday,
there should be a bit better coverage of storms across south
Florida, where the Slight Risk area inherited remains largely
unchanged. As the front pushes south, it will shove the bulk of the
tropical moisture into the Florida Straits and into the Bahamas.
This should work to limit storm coverage on future days, as a much
drier and cooler air mass continues to envelop the rest of the
state.

...New Mexico and Colorado...

The positively tilted upper level trough from Thursday will begin
to pivot to become neutrally tilted on Friday. This means the
southern end of the trough will get a boost to advance eastward,
while the northern end will largely stay in place. The result will
be a more south to north oriented axis of heavy rainfall,
stretching from the southern end of New Mexico north across much of
western Colorado. Moisture from the Pacific will also be drawn
northward along the New Mexico/Arizona border. This should expand
the rainfall footprint for Friday across much of the southern
portion of New Mexico and southeastern Arizona. Expect Friday to
the wettest day this week for New Mexico and Colorado.

CAMs guidance suggests the plume of moisture stretching NNE from
southeast Arizona through north-central New Mexico and into
Colorado will be the focus for additional convection capable of
producing flash flooding. With better southward extent, the storms
will be able to tap into some deeper moisture and instability from
the Pacific on Friday. This will make thunderstorm coverage Friday
greater than in previous days. Since the whole plume will also be
lifting north and east, expect a much larger area of rain to impact
the area Friday. Embedded thunderstorms among the mostly lighter
shower activity will be the foci for any potential flash flooding.
This will be particularly true in any areas where multiple rounds
of storms producing heavy rain occur.

...Northwest...

Shortwaves and vorticity maxes rounding the periphery of the
longwave trough will be the foci causing additional convection from
northern Idaho east across much of Montana. The expected rainfall
forecast has decreased the overall rainfall in this area. However,
mountain forcing may offset this in some areas.

Wegman

Day 3
Valid 12Z Sat Sep 13 2025 - 12Z Sun Sep 14 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM EASTERN NEW
MEXICO THROUGH SOUTHWESTERN KANSAS, AS WELL AS FOR A PORTION OF THE
URBAN CORRIDOR OF SOUTH FLORIDA...

...New Mexico through Kansas...

As the upper level trough over the Intermountain West becomes more
negatively tilted, a portion of the low level jet out ahead it will
draw deeper Gulf moisture north into the Panhandles and eastern New
Mexico and into southwestern Kansas. This will support a line of
storms that will develop over central New Mexico and then press
eastward into the Slight Risk area. Once over eastern New Mexico
and the Panhandles, the eastward progress of the storms will
diminish greatly, resulting in much slower-moving but still
organized storms. This will be the basis for training, resulting in
widely scattered instances of flash flooding where the storms are
the most persistent.

...South Florida...

The front over South Florida will finally push east and clear all
of the deepest tropical moisture well out into the Atlantic and
Bahamas by Sunday morning. Thus, expect Saturday to be a transition
day in the area...where there will still be storms, particularly
along the urban I-95 corridor from Miami through Palm Beach, but
there will be less coverage over Florida as the moisture is pushed
eastward out into the Atlantic. The newly issued Slight is a low-
confidence one, as once the front clears the state, that should end
the flooding threat. However, given the many days of daily
afternoon convection in the I-95 corridor, soils are sensitive
enough that even the reduced time and coverage of storms could
still cause widely scattered instances of flash flooding.

...Northern Plains...

Across the Northern Plains, ahead of the neutrally tilted trough
that is becoming negatively tilted, the northern extent of the low
level jet ahead of the trough will draw deeper Gulf moisture
westward across the Dakotas. This should support persistent
convection. However, this area of the Dakotas is fairly difficult
to flood, so despite the higher probability for training and heavy
rain, the area remains in a higher-end Marginal for now. A Slight
Risk upgrade may be needed for portions of the area as guidance
begins to resolve this part of the event across the northern
Plains.

Wegman


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!9Jmg4Iv0R4Pg7OB0PecCq6UcS8kIRJeXtLv_pg139xoe= 5M-3n7UoyS_Q-hndx8AL2mOfJ42PvSY_9GRZ0S3DQ0UBOI0$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!9Jmg4Iv0R4Pg7OB0PecCq6UcS8kIRJeXtLv_pg139xoe= 5M-3n7UoyS_Q-hndx8AL2mOfJ42PvSY_9GRZ0S3DLPwOcTE$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!9Jmg4Iv0R4Pg7OB0PecCq6UcS8kIRJeXtLv_pg139xoe= 5M-3n7UoyS_Q-hndx8AL2mOfJ42PvSY_9GRZ0S3DX0nO8A8$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 141601
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1201 PM EDT Sun Sep 14 2025

Day 1
Valid 16Z Sun Sep 14 2025 - 12Z Mon Sep 15 2025


...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL IN THE CENTRAL=20
DAKOTAS...

16Z Update...

Made only minor adjustments to the previous outlook areas. This
included narrowing the footprint of the Slight Risk area over the
Dakotas. The 12Z hi-res models are in generally good agreement,
indicating a narrow stripe of heavy amounts extending north from
south-central South Dakota to north-central North Dakota. The
Slight Risk reflects the area where the 12Z HREF shows high=20
neighborhood probabilities for amounts exceeding 3 inches and 5-10=20
year ARIs.

Pereira=20

Previous Discussion...

...Northern Plains...

Upper trough exiting the Rockies has split off its southern
portion into an upper low that will move onto the High Plains later
this morning. Southerly flow will continue across the Northern
Plains along with ample moisture -- PW anomalies +2 to +3 sigma --
as a surface low over SD moves northward later this afternoon.
Convergent flow toward the nose of the sfc-based instability
gradient just to the east is expected to promote some south-to-
north convection that may overlap areas that saw a few inches of
rain on Saturday. Maintained the Slight Risk outline here with a
Marginal Risk buffer extending to the south to the edge of the Sand
Hills.

...Central and Southern Plains...

Split the longer Marginal Risk area from the previous forecast
into its own entity and extended it even farther southward to the
Mexican border to account for another tick up in expected
convection from KS southward to TX. Storms should fire along and
ahead of a low-level confluence axis and within a stripe of deeper
moisture. Some of these areas in W TX saw a couple/few inches of
rain on Saturday and FFG values are lower. Some models do indicate
the potential for slow-moving or backbuilding cells, resulting in
locally heavy amounts and perhaps isolated flash flooding concerns.

Fracasso



Day 2
Valid 12Z Mon Sep 15 2025 - 12Z Tue Sep 16 2025


The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Fracasso


Day 3
Valid 12Z Tue Sep 16 2025 - 12Z Wed Sep 17 2025


...THERE ARE MARGINAL RISKS OF EXCESSIVE RAINFALL IN SOUTHERN NEW
MEXICO, THE CENTRAL PLAINS, AND COASTAL VIRGINIA...

...Southern New Mexico...

Moisture will start to nudge upward over southern NM (though much
more well west of there) with some afternoon instability and
expected isolated convection, mainly over the mountains close to
the Mexican border. Low-end Marginal Risk is outlined here though
activity should be rather isolated.

...Central Plains...

Positively-tilted trough over the Northern Rockies will move
eastward to the High Plains Tuesday afternoon. Broad westerly mid-
level flow amid increasing moisture will help fire off some storms
over at least NE near the better forcing but also southward into
KS. A Marginal Risk is outlined here for an isolated flash flood
threat.

...Coastal Virginia...

Over the past couple of days, the models have trended toward
bringing in an area of low pressure near the Outer Banks Tuesday
morning or so. Rain should spread inland on Monday with additional
and perhaps heavier rain on Wednesday. This area has been rather
dry recently and rain rates may not be all that high, but some convection-driven rain is possible depending on the flavor of this
area of low pressure. A Marginal Risk is depicted for
southeastern/coastal Virginia and far northeastern North Carolina
but with a lot of uncertainty in the rainfall
pattern/rates/duration.

Fracasso


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!43gDcxjrzfQPFqwB3NPeqY5KIp9THWswbO63JA0Lj3i1= rv6W3y0mgcWCaCEyyESquMtYEtMbVdikTjZRQsiiHmAWB9U$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!43gDcxjrzfQPFqwB3NPeqY5KIp9THWswbO63JA0Lj3i1= rv6W3y0mgcWCaCEyyESquMtYEtMbVdikTjZRQsii2tATJVo$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!43gDcxjrzfQPFqwB3NPeqY5KIp9THWswbO63JA0Lj3i1= rv6W3y0mgcWCaCEyyESquMtYEtMbVdikTjZRQsiii0DDd74$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 151957
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
357 PM EDT Mon Sep 15 2025

Day 1
Valid 16Z Mon Sep 15 2025 - 12Z Tue Sep 16 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
EASTERN NORTH CAROLINA AND SOUTHEASTERN VIRGINIA...

...Eastern North Carolina and Southeast Virginia...
WV imagery off the NC coast indicates convection associated with a
deepening low pressure. This feature is deepening in response to
potent closed low (500mb heights below the 10th percentile
according to NAEFS) digging across the Carolinas and interacting
with a stationary front offshore. Subtle upper diffluence in the
distant RRQ of a jet streak near New England is additionally
providing ascent, leading to pressure falls within the surface low.
This should continue to deepen the wave offshore, leading to
intensifying onshore moist flow (850mb winds reaching -3 sigma in
to the west) driving intense moisture confluence into NC/VA through
tonight as the low lifts very slowly north/northwest, likely
moving onshore the Outer Banks before 12Z Tuesday.

While there continues to be some uncertainty into the exact timing
and track of this low pressure system, guidance has trended
stronger with more pronounced moisture advection to the W/NW. This
will result in heavy rainfall spreading onshore from southeast
North Carolina through the Tidewater region of VA and potentially
reaching as far north as southern Delaware before Tuesday morning.
The heaviest rainfall is likely to fall along an axis of strong
900-700mb fgen aligned just NW of the surface low, with additional
heavy rain likely anywhere north of the low center due to
persistent onshore flow and convergence. In these areas, this
onshore flow will additionally surge instability to 250-500 J/kg,
especially this evening/tonight, which, while modest, will be
sufficient in the very moist environment to improve rainfall
efficiency and support rainfall rates of 1-2"/hr. Where these
train/repeat, total rainfall of 3-5" with locally higher amounts
are likely.

Although this area has been dry recently (7-day rainfall from AHPS
generally less than 5% with few exceptions) leading to elevated
FFG, this type of rainfall can still overwhelm the soils in
scattered locations. This is reflected by 12Z HREF 3-hr FFG
exceedance probabilities rising to around 20%, so despite the
antecedent dryness, and after coordination with WFOs MHX/RAH/AKQ, a
targeted SLGT risk was introduced with this D1 update.


...Ozarks...
A weak mid-level impulse pushing into a short-wavelength but high
amplitude ridge this evening will likely result in slow moving
showers and thunderstorms. While coverage is expected to be widely
scattered, rainfall rates within convection will likely reach
1-2"/hr in response to impressive thermodynamics characterized by
MUCAPE of 2000-3000 J/kg overlapping PWs of 1.5 to 1.75 inches.
These storms will additionally move quite slowly as 0-6km mean
winds will be just around 5 kts, with additionally chaotic and slow
propagation vectors. While locally this could result in 2-3" of
rain (HREF and REFS probabilities for exceeding 3" peak around
20-30%), this will fall atop dry soils leading to only an isolated
chance of FFG exceedance. Opted to hold off on a MRGL risk for this
area as the probability appears to be less than 5% for excessive
rainfall today.


Weiss


Day 2
Valid 12Z Tue Sep 16 2025 - 12Z Wed Sep 17 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
EASTERN NORTH CAROLINA AND VIRGINIA...

...Virginia and North Carolina...
The surface low moving onshore NC from Monday will occlude and then
begin to return to the east as the system vertically stacks beneath
an upper low. Despite the slow filling and opening of the parent
mid-level low, continued ascent through PVA (weak vorticity maxima
rotating around the low) and periods of enhanced upper diffluence,
especially north of the low, will result in sufficient ascent to
maintain heavy rainfall, especially the first half of Tuesday.
Although synoptic lift will gradually wane, continued impressive
onshore fetch on 850mb winds of 25-35 kts (and above the mean wind
by almost 1.5x) will continue to transport elevated PWs above 1.5
inches onshore while producing additional ascent through
confluence. This will result in persistent training of moderate
rainfall with embedded convective elements leading to rainfall
rates for which the HREF neighborhood probabilities indicate a
30-40% chance of exceeding 1"/hr at times.=20

Where these rain rates train most efficiently through anti-
parallel Corfidi vectors, additional rainfall on D2 could reach an=20 additional 2-4" with locally higher amounts, especially near the
NC/VA border. This is also the area most likely to receive heavy
rainfall on D1, so 48-hr rainfall could reach 5-8" with local 10"=20
amounts possible. The REFS is a bit farther north than the HREF
today, but is supported by the AIFS and the area of maximum upper
divergence, so the MRGL risk was expanded a bit to the north, and a
targeted SLGT risk was added where D2 rainfall most efficiently
overlaps D1, leading to the enhanced flash flood risk. This was
coordinated with the local WFOs.


...Southwest...
A weak shortwave will emerge beneath the elongated mid-level ridge
Tuesday evening, helping to enhance the otherwise typical diurnal
convective activity across parts of AZ/NM. This weak impulse will
impinge into increasingly favorable thermodynamics as low-level
S/SE flow pushes PWs to 1-1.25 inches collocated with MUCAPE that
will exceed 500 J/kg. This suggests a local maxima in convective
coverage across southern AZ and into southern NM. Outside of any
clusters that develop thanks to modest bulk shear as storms dive
off the terrain later in the period, convection will slow moving on
0-6km mean winds of just around 5-10 kts, leading to locally heavy
rainfall capable of producing isolated flash flooding.


...Central High Plains...
Amplifying trough across the Intermountain West will shed a
shortwave into the Central Plains during the latter half of Tuesday
into Tuesday night. This shortwave will impinge into a favorable
airmass to spawn convection, reflected by PW forecasts of around
1.25 inches overlapping MUCAPE exceeding 2000 J/kg. The primary
longwave trough and the accompanying height falls/PVA combined with
modest but intensifying upper diffluence will likely result in
surface low developing in the lee of the Rockies, with a
downstream warm front pushing into Nebraska serving as a convergent
boundary for additional ascent. This warm front will waffle
east/west in response to low-level jet energy pushing NW from
OK/KS, resupplying the favorable thermodynamics to support
convection.=20

Thunderstorms that develop across this area will likely be heavy=20
rain producers with 1-2"/hr rain rates supported by 30-40%=20
probabilities from the HREF. Storms that develop will be supported=20
as well by 24-40 kts of bulk shear to help organize convection into
clusters, with some training along boundaries also expected. Where
this rain is most pronounced, total rainfall could exceed 3 inches
in a few locations, with the greatest potential focused near the
KS/NE/CO juncture. Here, rainfall has been above normal the past 7
days as well, compromising soils and creating FFG as low as
2"/3hrs, so any additional heavy rain could cause runoff leading to
instances of flash flooding. The threat still appears MRGL as
inherited, but some cosmetic adjustments were made to refine the
area based on new guidance.

Weiss


Day 3
Valid 12Z Wed Sep 17 2025 - 12Z Thu Sep 18 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PARTS OF THE
NORTHERN AND CENTRAL PLAINS, SOUTHERN HIGH PLAINS, AND SOUTHEAST
FLORIDA...

20Z Update:
Changes to the forecast ERO areas were minimal with this update.

The MRGL risk across southeast Florida was maintained with little
changes needed in response to good model agreement and trends in a
surge of PWs lifting into the southern peninsula. With the previous
discussion highlighting well the risk, and the coordination
completed overnight with WFO MFL, only minor cosmetic adjustments
were required.

In the Northern Plains, the MRGL risk was expanded just slightly
downstream of an amplifying trough axis digging out of the
Intermountain West. However, the carving out of the Sand Hills was
continued in response to the overall modest probabilities for
exceedance of 3" QPF over higher FFG. The inherited MRGL risk was
just expanded slightly to cover the highest axes of the new model
QPF fields.

Finally, in the Southern Plains, did make some modest southward
adjustment to the inherited MRGL risk. The guidance has trended a=20
bit faster/farther southwest with the trailing cold front and=20
accompanying convection. This suggests that the heavier rainfall=20
may occur atop drier soils with higher FFG, limiting the flash=20
flood risk. There are still some low-end probabilities for heavy=20
rain exceeding FFG, especially in the NW portion of the adjusted=20
MRGL risk, so while the threat appears minimal, it was enough to=20
continue the risk area at this time.

Previous Discussions:

...Northern and Central Plains...
A strong mid-level shortwave trough will eject into the WY Front=20
Range and eventually close off across NE generating a maturing lee=20
cyclone across the Central High Plains. The setup will likely cause
quite a robust deformation signature on the northwest flank of the
cyclone with ensemble mean QPF placement situated over western NE=20
up through southwestern SD, arcing back into the nose of the warm-=20
conveyor belt on the northeast side of the system. This is a=20
classic mid-latitude lee cyclogenesis setup with a strong jet=20
coupling leading to broad large scale forcing and widespread precip
across the Plains. Eastern side of the cyclone will exhibit the=20
best convective potential while the deformation axis provides a=20
solid precip field with moderate to locally heavy rates for several
hrs. in that northwest side of the low. Totals >2" are forecast=20
within the means across western NE into SD with scattered elevated=20
QPF across the Missouri River basin located in eastern SD and NE.=20
This setup is conducive for at least some isolated to scattered=20
flash flood prospects considering the synoptic evolution. This was=20
enough to warrant a MRGL risk in those areas deemed the best chance
for heavy rain prospects.

...Southern High Plains...
Maturing lee side low to the north will help drag a trailing cold=20
front through the Central and Southern High Plains on Wednesday.=20
The front will slip south and southwest once down near the latitude
of the OK Panhandle, leading to a more textbook backdoor frontal=20
progression as it enters into the northern TX Panhandle and=20
northeast NM. Flow begins to run more parallel to the boundary in=20
these zones when assessing forecast soundings from relevant global=20 deterministic. The key in the setup is a relatively solid=20
isentropic ascent pattern in a small zone bordering CO/OK/NM/TX=20
with cross-section views over the area displaying a classic sloped=20
low-level surface FGEN with strong omega correlating to rapid=20
ascent as the front progresses through the area. Locally enhanced=20
corridor of precip will transpire along and in wake of the front=20
with local maxima of 1.5" to as much as 3" plausible during the=20
event. This could be enough for an isolated flash flood threat,=20
especially in those smaller urban areas situated across the 4 state intersection. A MRGL risk has been added to account for the=20
threat.

...Southeast Florida...
Stalled front with an enhanced moisture return across South FL=20
will lead to a heightened threat for flash flooding over the urban=20
centers of southeast FL. Deterministic output is scattered in the=20
exact location of the heaviest precip, ranging from the Keys up to=20
West Palm Beach and everywhere in- between. The setup is=20
historically favorable for flash flood concerns over the urban=20
zones of southeast FL with PWATs hovering between 2-2.3", a solid=20
1/1.5 deviations above normal. In coordination with the Miami WFO,=20
a MRGL was maintained for that urbanized coastal corridor between=20
West Palm down to Miami proper since this is the most likely=20
location for flash flooding in this type of setup. Will monitor=20
convective trends as we get closer to see if this necessitates any=20 expansion, or even a targeted upgrade.

...Mid-Atlantic States...
Although no MRGL risk was added at this time, the coastal low=20
plaguing NC/VA will continue to move slowly northward Wednesday,=20
spreading moisture via onshore flow into VA/MD/DE. The
probabilisticguidance suggests only a very low-end threat for 3"=20
of rainfall, but admittedly the guidance did not really pick up on=20
the current heavy rain signal for NC/VA until within 3 days either.
After coordination with AKQ, no MRGL risk was added at this time,=20
but with some history of "over-performing" rainfall upstream, it is
possible a targeted MRGL risk may be needed with later issuances.

Kleebauer/Weiss


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!-oIfPjzILcm4umx4GevHPBzmIF7pEeK0E54W9Ji00Amc= PdinIxvTM1oAViLzlMbCJnGHZoFwIdQV0BnXrp6azYzt8zk$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!-oIfPjzILcm4umx4GevHPBzmIF7pEeK0E54W9Ji00Amc= PdinIxvTM1oAViLzlMbCJnGHZoFwIdQV0BnXrp6aE9K4TMw$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!-oIfPjzILcm4umx4GevHPBzmIF7pEeK0E54W9Ji00Amc= PdinIxvTM1oAViLzlMbCJnGHZoFwIdQV0BnXrp6a29wOBZ0$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 170059
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
859 PM EDT Tue Sep 16 2025

Day 1
Valid 01Z Wed Sep 17 2025 - 12Z Wed Sep 17 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
SOUTHEASTERN VIRGINIA ALONG WITH SOUTHERN NEBRASKA INTO FAR
NORTHWEST KANSAS...

...Mid Atlantic...

...01Z Update...
Very little change to the Slight and Marginal areas based on the
latest observational trends, mesoanalysis, recent HRRR runs, and
HREF/RRFS rainfall exceedance probabilities. We were able to nudge
the southern boundary of the Slight Risk area to the NC-VA border,
while also pulling the Marginal Risk north as well to far northeast
NC. This given the sharp drying (TPW gradient) south of the main
precipitation shield.=20

Hurley

...16Z Update...
The marginal and slight risk areas were shifted north slightly=20
over portions of the Virginia Tidewater and northeastern North=20
Carolina based on model trends. A small marginal risk area was=20
introduced, in coordination with the local Billings office, over=20
portions of Yellowstone and the Absaroka Range below 10,000 feet=20
where easterly moisture advection into the terrain could generate=20
upslope enhanced precipitation over vulnerable soils. PWATs between
0.5-1 inch, low flash Flood guidance and HREF 24hr 1-3 inch=20
exceedance probabilities over 5% support some kind of isolated=20
flash potential.

Kebede

...Southwest...

Scattered convective pattern will initiate later this afternoon
and the early evening hours before fading with the loss of diurnal
heating. Current progs are for convection to be tied closer to the
terrain across southeast AZ into southern NM with isolated
signatures of >1"/hr plausible in the stronger cell cores. These
areas generally prone to runoff due to terrain complexities, as
well as remnant burn scars present in some locations. There was
very little change from the inherited MRGL risk with the forecast
running close to general continuity.

...Central High Plains...

...01Z Update...
Based on the latest trends with the observations (radar/satellite), mesoanalysis (strong deep-layer CAPE and low-level moisture
transport), along with the most recent HRRR runs and HREF/RRFS
rainfall exceedance probabilities, have included a targeted Slight
Risk area across parts of southwest to central NE. Based on these
recent trends, expect the highest risk to persist until 03-05Z.

Hurley=20

Previous discussion...

Strong shortwave trough ejection out of the interior Northwest=20
will lead to convective development and regional enhancement across
the Central High Plains. Greatest ascent is aligned with the=20
diffluent region of the mid-level shortwave with left-exit region=20
dynamics likely to maintain a prevalent heavy rain signature across
the western third of NE down into neighboring northeast CO and=20
northwest KS. Guidance has come into alignment with the axis of=20
heaviest precip centered near and just north of North Platte, NE=20
with the corridor extending south into southwestern NE and=20
northwest KS by the second half of the forecast period. 00z HREF=20 neighborhood probs for >3" are running between 20-40% across the=20
referenced area near North Platte and points south. This still=20
aligns well with the previous forecast MRGL risk leading to little=20
deviation in the current thinking. The areas of highest risk will=20
likely be smaller towns and urbanized areas, like North Platte that
are more susceptible to runoff.

Kleebauer


Day 2
Valid 12Z Wed Sep 17 2025 - 12Z Thu Sep 18 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PARTS OF THE
NORTHERN PLAINS...

...2030z update...

A slight risk was introduced over portions of western South Dakota
based on increasing qpf trends and better agreement on location of
deformation axis. FFGs are relatively low (0.75-2") over parts of
west and northwestern South Dakota with ongoing rainfall likely to
bring those values down by Wednesday.

A marginal risk was introduced over much of the Mid-Atlantic
coastal area due to recent qpf trends. Deterministic guidance have
increased qpf over an area extending from the Virginia Tidewater up
to Long Island New York where a plume of subtropical moisture is
likely to continue interacting with a slow moving surface front
propagating northward along the coast.

...Previous Discussion...

...Northern and Central Plains...

A strong mid-level shortwave trough will eject into the WY Front
Range and eventually close off across NE generating a maturing lee
cyclone across the Central High Plains. The setup will likely cause
quite a robust deformation signature on the northwest flank of the
cyclone with ensemble mean QPF placement situated over western NE
up through western SD into southern ND, arcing back into the nose
of the warm- conveyor belt (WCB) on the northeast side of the
system. This is a classic mid- latitude lee cyclogenesis setup with
a strong jet coupling leading to broad large scale forcing and
widespread precip across the Plains. Eastern side of the cyclone
will exhibit the best convective potential given the modest theta_E
advection pattern poleward within the WCB leading to scattered
thunderstorm potential from the Southern Plains to as far north as
the Northern Plains and adjacent Upper Midwest (Western MN).
Meanwhile, the deformation axis across NE/SD/ND will provide a
solid precip field with moderate to locally heavy rates for several
hrs. located in that northwest side of the low. Totals >2" are
forecast within the means across western NE into the Dakotas with
scattered elevated QPF across the Missouri River basin located in
eastern SD and NE down through KS and far western OK. This setup
is conducive for at least some isolated to scattered flash flood
prospects considering the broad synoptic scale evolution. A very
broad MRGL exists across much of the Northern and Central Plains
with a cull located over NE and northwest KS where the low center
will be present and drier air entrains into the region Wednesday
evening and beyond as the low intensifies and approaches occlusion
phase by Thursday AM.

...Southern High Plains...

Very little change in the previous forecast as run to run
continuity has allowed for negligible adjustments within the
previous MRGL risk.

A maturing lee side low to the north will help drag a trailing
cold front through the Central and Southern High Plains on
Wednesday. The front will slip south and southwest once down near
the latitude of the OK Panhandle, leading to a more textbook
backdoor frontal progression as it enters into the northern TX
Panhandle and northeast NM. Flow begins to run more parallel to the
boundary in these zones when assessing forecast soundings from
relevant global deterministic. The key in the setup is a relatively
solid isentropic ascent pattern in a small zone bordering
CO/OK/NM/TX with cross-section views over the area displaying a
classic sloped low-level surface FGEN with strong omega correlating
to rapid ascent as the front progresses through the area. Locally
enhanced corridor of precip will transpire along and in wake of the
front with local maxima of 1.5" to as much as 3" plausible during
the event. This could be enough for an isolated flash flood threat,
especially in those smaller urban areas situated across the four
state intersection.

...Southwest...

Another period of isolated to scattered convection is anticipated
over the terrain encompassing southern AZ up through the central
and eastern portions of NM with the primary threat being heavy
rainfall situated over more complex terrain and burn scar remnants.
Assessment of forecast soundings and hodographs indicate relatively
slower cell motions, a classic characteristic for flash flood
prospects over the desert southwest. Guidance reflects local 1-2"
totals scattered across the region extending from southeast AZ into
NM with some of the better signals focused within those mountain
ranges like the Huachucas and Sacramento's. This signal garnered
enough attention to warrant an addition of a MRGL to account for
the localized threat.

...Southeast Florida...

Stalled front with an enhanced moisture return across South FL
will lead to a heightened threat for flash flooding over the urban
centers of southeast FL. The setup is historically favorable for
flash flood concerns over the urban zones of southeast FL with
PWATs hovering between 2-2.3", a solid 1/1.5 deviations above
normal. CAMs guidance has recently come into range for at least the
first half of the period with a mixture of results ranging from
very little precip to multiple heavy convective cores impacting the
zone between PBI down to MFL. Neighborhood probs for >2" are pretty
high (>60%) across a large chunk of that above corridor, but
there's still a precipitous drop off in the probs for >3" with a
very low EAS signal accompanying. At this juncture, the prospects
for heavy rainfall seem to be more isolated in nature, but the
environment is leaning favorable for any cells to potentially drop
appreciable amounts of rain in a short period of time. The heaviest
rainfall totals among guidance seem relegated to the FL Keys, an
area that historically is difficult for flash flood prospects just
due to the sandier soils and much smaller land footprint available.
The previous MRGL risk was relatively maintained given the setup
and the chance for the signal to grow, but for now remains more
within the lower end of the risk threshold.

Kleebauer


Day 3
Valid 12Z Thu Sep 18 2025 - 12Z Fri Sep 19 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE NORTHERN PLAINS, MISSISSIPPI RIVER VALLEY, SOUTHWEST U.S.,
AND SOUTHEAST FLORIDA...

...2030z update...

The marginal risk in the Southwest expanded across southern
Arizona and into far southwestern New Mexico, due to an increased
signal for convection. The marginal over the Plains was also
expanded a bit into the Texas/Oklahoma panhandle area. There's
uncertainty on where the maximum qpf axis will set up over the
Northern Plains on Thursday. No changes were made to the southeast
Florida marginal.

Kebede

...Previous Discussion...

...Central U.S...

Broad, occluding cyclone over the center of the CONUS will lead to
a continuation of scattered convection on the eastern flank of the
disturbance with a continued axis of deformation over parts of the
Dakotas. Flash flood potential will be relatively modest
considering the cyclone undergoing a deteriorating phase by the D3
juncture. Ensemble means are generally between 0.5-1" within the
convective zone in the decaying warm-conveyor belt (WCB) with 1-2"
located within the axis of deformation. The best flash flood risks
will likely coincide in the convective elements just due to the
nature of enhanced rates, so overall we're looking at a mid-grade
MRGL risk for the period, but will assess if there needs to be any
targeted upgrades as we get closer to the period. For now, the
broad MRGL inherited will suffice.

...Southwest...

Moisture advection from the northeast edge of tropical cyclone
Mario off the California Baja will make its presence known across
Southern CA into adjacent NV/AZ by Thursday morning leading to an
increasing threat of scattered to widespread convective initiation
during peak diurnal instability. As PWATs surge to 2-3 deviations
above normal by Thursday afternoon and beyond across SoCal, the
environment will be conducive for several convective cores to
produce fairly heavy rainfall potential, especially over the
terrain focused from Big Sur, south into the Transverse and
Peninsular Ranges. The threat for thunderstorms will exist over the
SoCal deserts, an area very prone to flash flooding due to the high
runoff capabilities and multitude of dry arroyos littered across
the region. The northern periphery will likely make its presence
into southern NV, another area prone to flash flooding due to
similar issues and added complex topography scattered about the
area. Totals of 1+" will be common with a likelihood of a few 2+"
totals considering the environment likely in place. A MRGL risk is
currently forecast, but would not be surprised to see an upgrade in
future forecasts, especially over portions of SoCal.

...Southeast Florida...

A rinse and repeat setup carrying over from D2 will lead to a
continued threat of heavy convection across much of South Florida.
Frontal alignment still indicates a scattered to widespread
convective posture across southeast FL where the urban corridor
will be under threat for more heavy rainfall and flash flood
prospects. The greatest threat will lie within that zone from
Melbourne down to Miami with some of the ensemble means greatest
near West Palm Beach and Port St. Lucie. A MRGL risk exists once
again for the defined area above between MLB to MFL.

Kleebauer


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!5fbjs7HIzYzZKKSCFYCu6NKR_d0rb25k-vPgadY_yBYh= -fPN1e5AkgTdrWmudWfaaGFI3Wc1jPQDWE3M13jiakCRirU$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!5fbjs7HIzYzZKKSCFYCu6NKR_d0rb25k-vPgadY_yBYh= -fPN1e5AkgTdrWmudWfaaGFI3Wc1jPQDWE3M13jimtkpDow$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!5fbjs7HIzYzZKKSCFYCu6NKR_d0rb25k-vPgadY_yBYh= -fPN1e5AkgTdrWmudWfaaGFI3Wc1jPQDWE3M13ji24_bLZI$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 170359
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1159 PM EDT Tue Sep 16 2025

Day 1
Valid 0357Z Wed Sep 17 2025 - 12Z Thu Sep 18 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
SOUTHEASTERN VIRGINIA ALONG WITH SOUTHERN NEBRASKA INTO FAR
NORTHWEST KANSAS...

...04z Update...

Given radar trends across western IA into eastern NE, a MRGL risk
was expanded to include these areas to account for an isolated risk
of flash flooding within the next 3-6 hours. For more on this
setup, please refer to MPD #1098.

Kleebauer

...Mid Atlantic...

...01Z Update...
Very little change to the Slight and Marginal areas based on the
latest observational trends, mesoanalysis, recent HRRR runs, and
HREF/RRFS rainfall exceedance probabilities. We were able to nudge
the southern boundary of the Slight Risk area to the NC-VA border,
while also pulling the Marginal Risk north as well to far northeast
NC. This given the sharp drying (TPW gradient) south of the main
precipitation shield.

Hurley

...16Z Update...
The marginal and slight risk areas were shifted north slightly
over portions of the Virginia Tidewater and northeastern North
Carolina based on model trends. A small marginal risk area was
introduced, in coordination with the local Billings office, over
portions of Yellowstone and the Absaroka Range below 10,000 feet
where easterly moisture advection into the terrain could generate
upslope enhanced precipitation over vulnerable soils. PWATs between
0.5-1 inch, low flash Flood guidance and HREF 24hr 1-3 inch
exceedance probabilities over 5% support some kind of isolated
flash potential.

Kebede

...Southwest...

Scattered convective pattern will initiate later this afternoon
and the early evening hours before fading with the loss of diurnal
heating. Current progs are for convection to be tied closer to the
terrain across southeast AZ into southern NM with isolated
signatures of >1"/hr plausible in the stronger cell cores. These
areas generally prone to runoff due to terrain complexities, as
well as remnant burn scars present in some locations. There was
very little change from the inherited MRGL risk with the forecast
running close to general continuity.

...Central High Plains...

...01Z Update...
Based on the latest trends with the observations (radar/satellite), mesoanalysis (strong deep-layer CAPE and low-level moisture
transport), along with the most recent HRRR runs and HREF/RRFS
rainfall exceedance probabilities, have included a targeted Slight
Risk area across parts of southwest to central NE. Based on these
recent trends, expect the highest risk to persist until 03-05Z.

Hurley

Previous discussion...

Strong shortwave trough ejection out of the interior Northwest
will lead to convective development and regional enhancement across
the Central High Plains. Greatest ascent is aligned with the
diffluent region of the mid-level shortwave with left-exit region
dynamics likely to maintain a prevalent heavy rain signature across
the western third of NE down into neighboring northeast CO and
northwest KS. Guidance has come into alignment with the axis of
heaviest precip centered near and just north of North Platte, NE
with the corridor extending south into southwestern NE and
northwest KS by the second half of the forecast period. 00z HREF
neighborhood probs for >3" are running between 20-40% across the
referenced area near North Platte and points south. This still
aligns well with the previous forecast MRGL risk leading to little
deviation in the current thinking. The areas of highest risk will
likely be smaller towns and urbanized areas, like North Platte that
are more susceptible to runoff.

Kleebauer


Day 2
Valid 12Z Thu Sep 18 2025 - 12Z Fri Sep 19 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PARTS OF THE
NORTHERN PLAINS...

...2030z update...

A slight risk was introduced over portions of western South Dakota
based on increasing qpf trends and better agreement on location of
deformation axis. FFGs are relatively low (0.75-2") over parts of
west and northwestern South Dakota with ongoing rainfall likely to
bring those values down by Wednesday.

A marginal risk was introduced over much of the Mid-Atlantic
coastal area due to recent qpf trends. Deterministic guidance have
increased qpf over an area extending from the Virginia Tidewater up
to Long Island New York where a plume of subtropical moisture is
likely to continue interacting with a slow moving surface front
propagating northward along the coast.

...Previous Discussion...

...Northern and Central Plains...

A strong mid-level shortwave trough will eject into the WY Front
Range and eventually close off across NE generating a maturing lee
cyclone across the Central High Plains. The setup will likely cause
quite a robust deformation signature on the northwest flank of the
cyclone with ensemble mean QPF placement situated over western NE
up through western SD into southern ND, arcing back into the nose
of the warm- conveyor belt (WCB) on the northeast side of the
system. This is a classic mid- latitude lee cyclogenesis setup with
a strong jet coupling leading to broad large scale forcing and
widespread precip across the Plains. Eastern side of the cyclone
will exhibit the best convective potential given the modest theta_E
advection pattern poleward within the WCB leading to scattered
thunderstorm potential from the Southern Plains to as far north as
the Northern Plains and adjacent Upper Midwest (Western MN).
Meanwhile, the deformation axis across NE/SD/ND will provide a
solid precip field with moderate to locally heavy rates for several
hrs. located in that northwest side of the low. Totals >2" are
forecast within the means across western NE into the Dakotas with
scattered elevated QPF across the Missouri River basin located in
eastern SD and NE down through KS and far western OK. This setup
is conducive for at least some isolated to scattered flash flood
prospects considering the broad synoptic scale evolution. A very
broad MRGL exists across much of the Northern and Central Plains
with a cull located over NE and northwest KS where the low center
will be present and drier air entrains into the region Wednesday
evening and beyond as the low intensifies and approaches occlusion
phase by Thursday AM.

...Southern High Plains...

Very little change in the previous forecast as run to run
continuity has allowed for negligible adjustments within the
previous MRGL risk.

A maturing lee side low to the north will help drag a trailing
cold front through the Central and Southern High Plains on
Wednesday. The front will slip south and southwest once down near
the latitude of the OK Panhandle, leading to a more textbook
backdoor frontal progression as it enters into the northern TX
Panhandle and northeast NM. Flow begins to run more parallel to the
boundary in these zones when assessing forecast soundings from
relevant global deterministic. The key in the setup is a relatively
solid isentropic ascent pattern in a small zone bordering
CO/OK/NM/TX with cross-section views over the area displaying a
classic sloped low-level surface FGEN with strong omega correlating
to rapid ascent as the front progresses through the area. Locally
enhanced corridor of precip will transpire along and in wake of the
front with local maxima of 1.5" to as much as 3" plausible during
the event. This could be enough for an isolated flash flood threat,
especially in those smaller urban areas situated across the four
state intersection.

...Southwest...

Another period of isolated to scattered convection is anticipated
over the terrain encompassing southern AZ up through the central
and eastern portions of NM with the primary threat being heavy
rainfall situated over more complex terrain and burn scar remnants.
Assessment of forecast soundings and hodographs indicate relatively
slower cell motions, a classic characteristic for flash flood
prospects over the desert southwest. Guidance reflects local 1-2"
totals scattered across the region extending from southeast AZ into
NM with some of the better signals focused within those mountain
ranges like the Huachucas and Sacramento's. This signal garnered
enough attention to warrant an addition of a MRGL to account for
the localized threat.

...Southeast Florida...

Stalled front with an enhanced moisture return across South FL
will lead to a heightened threat for flash flooding over the urban
centers of southeast FL. The setup is historically favorable for
flash flood concerns over the urban zones of southeast FL with
PWATs hovering between 2-2.3", a solid 1/1.5 deviations above
normal. CAMs guidance has recently come into range for at least the
first half of the period with a mixture of results ranging from
very little precip to multiple heavy convective cores impacting the
zone between PBI down to MFL. Neighborhood probs for >2" are pretty
high (>60%) across a large chunk of that above corridor, but
there's still a precipitous drop off in the probs for >3" with a
very low EAS signal accompanying. At this juncture, the prospects
for heavy rainfall seem to be more isolated in nature, but the
environment is leaning favorable for any cells to potentially drop
appreciable amounts of rain in a short period of time. The heaviest
rainfall totals among guidance seem relegated to the FL Keys, an
area that historically is difficult for flash flood prospects just
due to the sandier soils and much smaller land footprint available.
The previous MRGL risk was relatively maintained given the setup
and the chance for the signal to grow, but for now remains more
within the lower end of the risk threshold.

Kleebauer


Day 3
Valid 12Z Fri Sep 19 2025 - 12Z Sat Sep 20 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE NORTHERN PLAINS, MISSISSIPPI RIVER VALLEY, SOUTHWEST U.S.,
AND SOUTHEAST FLORIDA...

...2030z update...

The marginal risk in the Southwest expanded across southern
Arizona and into far southwestern New Mexico, due to an increased
signal for convection. The marginal over the Plains was also
expanded a bit into the Texas/Oklahoma panhandle area. There's
uncertainty on where the maximum qpf axis will set up over the
Northern Plains on Thursday. No changes were made to the southeast
Florida marginal.

Kebede

...Previous Discussion...

...Central U.S...

Broad, occluding cyclone over the center of the CONUS will lead to
a continuation of scattered convection on the eastern flank of the
disturbance with a continued axis of deformation over parts of the
Dakotas. Flash flood potential will be relatively modest
considering the cyclone undergoing a deteriorating phase by the D3
juncture. Ensemble means are generally between 0.5-1" within the
convective zone in the decaying warm-conveyor belt (WCB) with 1-2"
located within the axis of deformation. The best flash flood risks
will likely coincide in the convective elements just due to the
nature of enhanced rates, so overall we're looking at a mid-grade
MRGL risk for the period, but will assess if there needs to be any
targeted upgrades as we get closer to the period. For now, the
broad MRGL inherited will suffice.

...Southwest...

Moisture advection from the northeast edge of tropical cyclone
Mario off the California Baja will make its presence known across
Southern CA into adjacent NV/AZ by Thursday morning leading to an
increasing threat of scattered to widespread convective initiation
during peak diurnal instability. As PWATs surge to 2-3 deviations
above normal by Thursday afternoon and beyond across SoCal, the
environment will be conducive for several convective cores to
produce fairly heavy rainfall potential, especially over the
terrain focused from Big Sur, south into the Transverse and
Peninsular Ranges. The threat for thunderstorms will exist over the
SoCal deserts, an area very prone to flash flooding due to the high
runoff capabilities and multitude of dry arroyos littered across
the region. The northern periphery will likely make its presence
into southern NV, another area prone to flash flooding due to
similar issues and added complex topography scattered about the
area. Totals of 1+" will be common with a likelihood of a few 2+"
totals considering the environment likely in place. A MRGL risk is
currently forecast, but would not be surprised to see an upgrade in
future forecasts, especially over portions of SoCal.

...Southeast Florida...

A rinse and repeat setup carrying over from D2 will lead to a
continued threat of heavy convection across much of South Florida.
Frontal alignment still indicates a scattered to widespread
convective posture across southeast FL where the urban corridor
will be under threat for more heavy rainfall and flash flood
prospects. The greatest threat will lie within that zone from
Melbourne down to Miami with some of the ensemble means greatest
near West Palm Beach and Port St. Lucie. A MRGL risk exists once
again for the defined area above between MLB to MFL.

Kleebauer


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!_Trd-sms-I6BApOLdyBtkW5ErPxzWVXGAkyXiMdjCJI8= MTDmD-QedeD-WtF92XnD46sSDFsJ0cKJjN6R17OJbNxhb14$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!_Trd-sms-I6BApOLdyBtkW5ErPxzWVXGAkyXiMdjCJI8= MTDmD-QedeD-WtF92XnD46sSDFsJ0cKJjN6R17OJKUtwU8c$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!_Trd-sms-I6BApOLdyBtkW5ErPxzWVXGAkyXiMdjCJI8= MTDmD-QedeD-WtF92XnD46sSDFsJ0cKJjN6R17OJ84Evbr4$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 240012
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
812 PM EDT Tue Sep 23 2025

Day 1
Valid 01Z Wed Sep 24 2025 - 12Z Wed Sep 24 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE OHIO AND MID TO LOWER MISSISSIPPI VALLEYS INTO THE ARKLATEX...

...Ohio and Mississippi Valley's into ArkLaTex...

01z Update: Surface and upper level progression over the Southern
Plains will continue through the overnight hours with large scale=20
ascent still primed to impact the Mid to Lower Mississippi Valley=20
tonight into the ArkLaTex early Wednesday morning. Thunderstorm
genesis will occur over southeast OK into western AR and move
east-southeast with the mean flow as a cold front propagates out of
OK and shoves the pattern downstream. Heavy rainfall within a
corridor of modest low to mid-level lapse rates and surface based
instability will aid in convective schema leading to locally heavy
rates between 1-2"/hr at peak intensity with the strongest cores
capable of ~3"/hr given the PWATs near 2" in place over the
aforementioned area. Copious amounts of rain and flash flood
signals were prevalent earlier in the D1 period, and that threat
will continue its migration south along and ahead of the cold
front. This was more than enough to favor a general maintenance of
the SLGT risk from prior forecast, but did scale back on the
northern and western flank of the risk due to the heavy rainfall
prospects likely done with the frontal approach imminent, and/or
loss of favored ascent.=20

The threat for scattered heavy rainfall expands eastward into the=20
Southern Ohio, and Tennessee Valley's as a quasi- stationary front=20
bisects the area from the Ozarks into the western reaches of the=20
Ohio Valley. Expectation is for smaller mid- level perturbations to
ripple eastward along the front enacting focused ascent within the
boundary confines which could spell for periods of locally heavy=20
rain with some training potential in-of the front. Signal is not=20
nearly as prolific as upstream over the Mississippi Valley, mainly=20
due to the lower instability forecast over the area. That said,=20
lower FFG's add favor to a threat overnight as any cell >1"/hr will
have the capability to induce some flash flood prospects. As a=20
result, have maintained the previous SLGT risk forecast over the=20
area with some minor expansion to the east given recent hi-res
trends.=20

...Coastal Central California...

01z Update: Primary threat for flash flooding this evening across
CA will be situated within any remnant burn scars that exhibit
those isolated pockets of much lower FFG's that would favor a
better threat for flash flooding. The setup was forecast to occur
this evening, so there was no reason to deviate from continuity.
The previous MRGL was maintained with no changes.=20

...Kansas...=20

01z Update: Shortwave ejection out of the Front Range will slowly
migrate eastward with a threat of heavy rain from convection
situated in-of the axis of a weak nocturnal LLJ converging with a
residual quasi-stationary front over northwest KS. The threat is
very isolated in nature, but hi-res continues to depict a small
axis of heavy rain potential from the CO/KS border near Goodland
down into Dodge City during the evening. The threat remains within
the lower bounds of the MRGL risk threshold, but still has merit,
so maintained continuity over the region and removed the risk
downstream over central and eastern KS as the threat there has
ended.=20

Kleebauer


Day 2
Valid 12Z Wed Sep 24 2025 - 12Z Thu Sep 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE
TENNESSEE AND OHIO VALLEY REGIONS...

20Z Update:
No significant adjustments made to this update with the greatest
threat of intense rain rates and repeated rounds of thunderstorms
over the TN and OH Valleys into portions of the central
Appalachians. Other areas with locally higher rainfall and rain
rates are across portions of northern NJ, eastern PA, and southern
NY late in the period and then across portions of eastern TX as the
convective complexes shift southward.

---previous discussion---

Anomalous PW and 850-700 moisture flux values will stretch across
a large area from the Lower MS Valley, and into the TN & OH
Valleys, Central Appalachians and the Mid- Atlantic, ahead of the
amplifying longwave trof stretching from the Great Lakes, southward
into the Lower MS Valley. There still is a fair amount of qpf
spread with the max axis day 2. WPC is leaning more toward the
multi model ensemble qpf mean/NBM to drive our qpf and excessive
rainfall axes. This will support a widespread axis of moderate to
heavy precip amounts from eastern TX into the Lower MS Valley, TN
and OH Valleys. While a large portion of the day 2 QPF and ERO axes
are currently in moderate to severe drought, there may be overlap
in qpf areas from day 2 and what has fallen over the past 24 hours
from eastern TN into central to eastern KY, and the Upper OH Valley
region. The previous slight risk was narrowed to better fit this
potential overlap areas. The marginal risk was also trimmed
significantly from southern L.P. of MI, IL, southeast MO and AR to
better fit the latest qpf update.

...Central California...
The slow moving closed low approaching the central CA coast late
day 1 will continue to push slowly eastward day 2 and push inland
by early Thursday morning. Similar to the day 1 period, an axis of
anomalous PW values, 2 to 3 standard deviations above the mean,
will persist to the east northeast of the closed low across Central
CA. Scattered convection in this anomalous PW axis will support
locally heavy rains across Central CA and isolated runoff issues,
especially across burn scar regions.

...Far southeast Arizona into New Mexico...
No changes made to the previous marginal risk area across this
region. Scattered convection possible, with localized heavy rain
and isolated runoff issues, especially in burn scar regions.

Oravec

Day 3
Valid 12Z Thu Sep 25 2025 - 12Z Fri Sep 26 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND FAR SOUTHWEST NEW MEXICO...

The slow moving closed low moving inland into Central CA day 2 will
drop back to the south southeast toward Southern CA day 3. This
system will continue to have an area of anomalous PW values in the
vicinity of the upper center across Central CA into the Great
Basin. This closed low will also begin to tap anomalous PW values
over northwestern Mexico, transporting them into southeast Arizona
day 3. Model consensus is for a max precip area over Southeast
Arizona and far southwest New Mexico. The previous slight risk
across this area was only modified slightly, expanding it slightly
to the north and east to cover the model max qpf spread. Only some
minor changes to the marginal risk to the northwest of this across
northern AZ, southern NV, far southwest UT and into the central
Sierra. Locally heavy rains and isolated runoff issues possible
across these areas, especially over burn scars.

...Southern to Central Appalachians...
There will continue to be a broad axis of above average PW values
pushing eastward day 3 ahead of the elongated upper trof
stretching from the Great Lakes into the OH and TN Valleys. There
is a lot of qpf differences in this high PW axis, leading to low
confidence in where to put risk areas. Much of the eastern U.S. is
in drought conditions with low relative soil moisture levels. One
exception is over portions of the Southern to Central Appalachians
from eastern TN/far western NC/far southwest VA and eastern WV.
Kept the day 3 marginal confined to these areas and removed the
broader marginal from the previous issuance that extended north and
east into the Mid-Atlantic and southwestward to the Gulf Coast.


Oravec

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!4p_bm-eNh2_g7NQ8dqT5VqOJxwnnOneinigyAjdiEhEF= 8Vp84CGLuHD8UTziNOgK9SJGyrhcRLuNlIMz9JDU5Sc5mvY$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!4p_bm-eNh2_g7NQ8dqT5VqOJxwnnOneinigyAjdiEhEF= 8Vp84CGLuHD8UTziNOgK9SJGyrhcRLuNlIMz9JDUFyNPMwI$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!4p_bm-eNh2_g7NQ8dqT5VqOJxwnnOneinigyAjdiEhEF= 8Vp84CGLuHD8UTziNOgK9SJGyrhcRLuNlIMz9JDUFxuMuKM$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 241902
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
302 PM EDT Wed Sep 24 2025

Day 1
Valid 16Z Wed Sep 24 2025 - 12Z Thu Sep 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE
TENNESSEE AND OHIO VALLEY REGIONS, ALONG WITH PARTS OF THE WESTERN
GULF COAST INTO THE LOWER MISSISSIPPI VALLEY...

...Southern Plains to the Central and Southern Appalachians...

...1600 UTC Update...

Based on the rainfall that has already fallen, along with the 12Z
CAM guidance (including HREF probabilistic suite), have expanded
the Slight Risk area to include western TN and more of the TN
Valley (northeast MS, northern AL, and northwest GA). This
expansion picks up on the enhanced HREF probabilities of 2+ inch/hr
rainfall rates, along with the higher probs of exceeding 5.00"
(isolated areas near 30 percent) through the remainder of the day 1
period (through 12Z Thu).

Meanwhile, have also expanded the Slight Risk area across parts of
the Lower MS Valley to eastern TX and along much of the TX coast.
This was a fairly sizable shift from the previous forecast, and
was based largely from the latest (12Z) CAM guidance as well as
observational trends. While the coverage may be more isolated than
scattered, the thermodynamic parameters (high TPWs around 2" and
mixed-layer CAPEs of 2000-2500 J/Kg) are optimal in maximizing the precipitation efficiency. The latest CAMs, especially HREF
probabilities, continue to show the potential for a "high-end"
heavy rainfall event, again even if more isolated than scattered.
Certainly enough to justify the more enhanced ERO risk (Slight vs.
Marginal). Within this expanded Slight Risk area, the 12Z HREF
indicated probabilities have climbed to 40-50% in areas from
northeast TX into southern AR-northern LA. In addition, 5+ inch
probabilities are now 50-60%+ across a small portion of south-
central TX.

...Previous discussion...

Composite radar this morning shows widespread showers and storms
extending from the Ohio Valley back into the southern Plains. The
overnight CAMs indicate that ongoing storms along the far eastern Oklahoma-Texas border into southern Arkansas will remain organized
into the late morning as the drift slowly south, with training
storms likely to produce heavy amounts across portions of
northeastern Texas and northwestern Louisiana. Supported by
shortwave energy moving through the base of a broader-scale
positively-tilted upper trough and PWs at or above 2 inches, HREF
probabilities indicate locally heavy amounts exceeding 3 inches are
likely. However, dry soil conditions, reflected by high FFGs, are
expected to limit the threat for widespread flooding concerns.

As energy continues to move through the base of the upper trough,
an area of low pressure is expected to become better organized and
track northeast through the Ohio Valley beginning later this
afternoon and continuing into the overnight. Deep southwesterly
flow ahead of the wave will support increasing moisture, with PW
anomalies increasing to over 2 std dev above normal per the GFS.
Given the ongoing rains and relatively wetter soil conditions
(lower FFGs), a Slight Risk extending from far northern Alabama to
far southern Ohio and western West Virginia was maintained. HREF
probabilities indicate that amounts of 1-2 inches will be common,
with locally heavier amounts over 3 inches possible within the
Slight Risk area.

In the wake of the low, showers and storms producing heavier rates
are expected along the trailing front as it sinks south through
the lower Mississippi Valley and along the upper Texas coast back
into South Texas. Here too, the HREF is indicating locally heavy
amounts over 3 inches are likely. But similar to areas to the
north, higher FFGs suggest flooding issues will be mostly contained
to vulnerable areas, including urbanized centers.

...Northeast...

The general consensus of the CAMs shows an area of showers and
storms moving northeast well in advance of the system over the Ohio
Valley. Supported by deepening moisture along a slow-moving
boundary and increasing mid-to-upper level forcing, showers and
storms will advance northeast across Pennsylvania, with repeating
storms potentially resulting in locally heavy amounts from
northeastern Pennsylvania into the Hudson Valley, parts of far
western New England, and the NYC area. A A Marginal Risk was
maintained for areas where the HREF shows higher probabilities for
amounts over 2 inches and where FFGs are relatively lower.

...Central California...

A slow-moving upper low currently offshore will drift north and
begin moving inland Thursday morning. With anomalous moisture
remaining in place (2.5-3 std dev above normal), locally heavy
amounts will remain possible. Reflecting the high HREF
probabilities for amounts over an inch, a Marginal Risk was
maintained along the central California Coast from the Monterey
Bay south and along the adjacent mountains.

Hurley/Pereira


Day 2
Valid 12Z Thu Sep 25 2025 - 12Z Fri Sep 26 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND FAR SOUTHWEST NEW MEXICO...

...Southwest to Sierra Nevada...

After moving inland early Thursday, the closed low over central
California is forecast to drop south into southern California by
early Friday. With ample moisture remaining in place (2-3 std
dev above normal) near and east of the upper center, locally heavy
amounts are possible from the Sierra Nevada east into southern
Nevada and southwestern Utah.

As the center drops south, increasing southerly flow east of the
low will draw deeper moisture up from Mexico, fueling widespread
shower and thunderstorm coverage, especially across southeastern
and central Arizona into southwestern New Mexico. A Slight Risk
was maintained across this area where PWs are forecast to increase
to 1-2 standard deviations above normal by the afternoon.

...Northeast...

Unsettled weather developing Day 1 is forecast to continue into
Thursday as showers and storms continue to develop ahead of the
system lifting out of the Ohio Valley into the Northeast.
Strengthening southwesterly flow along the Mid Atlantic coast into
the Northeast will support deepening moisture (PWs increasing to ~2
inches) and an increasing threat for heavy rainfall rates. A
Marginal Risk was maintained from northern New Jersey into southern
New England, where HREF probabilities indicate that localized
amounts over 3 inches are possible late Thursday morning into the
afternoon.

...Southern Appalachians into parts of the Southeast and Eastern=20
Gulf Coast...

...2000 UTC Update...

Amplifying mid-upper trough digging into the northwest and north-=20
central Gulf Thu-Thu night will slow the eastward progression of=20
the surface cold front and thus favorable pre-frontal buoyant=20
airmass (ribbon of higher TPW and deep-layer instability). More=20
protracted period of favorable low-level moisture transport ahead=20
of the upper trough/surface front. 12Z HREF probabilities depict
this idea well, with several hours of spotty areas with enhanced=20
probs for 1-2+ in/hr rainfall rates. Therefore, supported by the
latest CSU UFVS-verified ERO First-Guess field, have expanded the
Marginal Risk south to the MS-AL-western FL Panhandle Gulf Coast.=20


...Previous Discussion...

The consensus of the latest guidance indicates that showers and
storms developing along and ahead of the cold front trailing the
low moving through the Northeast will be generally progressive.
With widespread heavy amounts not expected and FFGs high, the
previous Marginal Risk was removed from much of the Mid Atlantic.
However, some models do show the potential for training storms to
produce some localized heavy amounts (2+ inches) across parts of
the southern Appalachians, where a small Marginal Risk was
maintained.

Hurley/Pereira


Day 3
Valid 12Z Fri Sep 26 2025 - 12Z Sat Sep 27 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND SOUTHWEST NEW MEXICO...

...Southwest...

A second day of numerous showers and storms is expected across the
Southwest, especially for much of southeastern Arizona and parts of southwestern New Mexico. The upper low setting into southern
California the previous period is expected to move little this day,
remaining centered near the California/Mexico border. This will
help to maintain anomalous moisture across the region, fueling
widespread shower and thunderstorm coverage during the afternoon
and evening hours. A Slight Risk, with a footprint similar to the
Day 2 area, was maintained for Day 3 across parts of Arizona and
New Mexico.

...Southeast...

A boundary will remain in place across the Southeast as an upper
trough evolves into a closed low that is forecast to linger beyond
the period. Moisture and energy lifting ahead of the closing system
will support periods of shower and storms. While the guidance at
this point is not signaling any widespread heavy amounts, the
pattern does lend itself to at least the threat for locally heavy
amounts, which may raise at least isolated flooding concerns.

Pereira

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!7h4VVW7j7L5JsErW2RNQmscZ04LZff35tUvNiuqwwR1X= Ab5Lcbz3WllKKKh2XWXbxH3PmOkY19s6T_hRas36BwJgqKg$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!7h4VVW7j7L5JsErW2RNQmscZ04LZff35tUvNiuqwwR1X= Ab5Lcbz3WllKKKh2XWXbxH3PmOkY19s6T_hRas36N8rbaAc$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!7h4VVW7j7L5JsErW2RNQmscZ04LZff35tUvNiuqwwR1X= Ab5Lcbz3WllKKKh2XWXbxH3PmOkY19s6T_hRas36NAnUHvc$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 031952
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
352 PM EDT Fri Oct 3 2025

Day 1
Valid 16Z Fri Oct 03 2025 - 12Z Sat Oct 04 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
EASTERN FLORIDA AND THE INTERMOUNTAIN WEST...

...Florida's East Coast...

For the 16Z Update, the Slight Risk centered along Florida's
Treasure Coast was removed. While easterly flow is still expected
to support showers and storms, with isolated heavy amounts possible
along Florida's East Coast, the consensus of the HREF/RRFS has
trended down along the Treasure Coast -- showing the focus for
deeper moisture and heavier amounts further south. Probabilities
from the HREF/RRFS now indicate the greatest chance for heavy
amounts through the remainder of Day 1 is across Southeast Florida,
which may result in runoff concerns, especially if they set up
over the urbanized areas. However, confidence in the details is
limited, with some indication that the heaviest amounts may set up
west of the urbanized areas over the Everglades. Therefore,
maintained just a Marginal Risk for now.

...Great Basin...

Additional rainfall is forecast to occur beneath the upper low,
which will continue propagating through the interior West today.
Recent heavy rainfall over portions of the Great Basin will likely
prime surfaces for runoff from additional precipitation. Burn
scars in central and southern Idaho continue to be of concern from
today's storms, the bulk of which should occur this morning into
afternoon before the upper low moves directly over the Great Basin
and instability weakens. HREF EAS exceedance probabilities of over
1 inch are between 15-35% over northern/central Nevada where PWATs
will be between 2-3 standard deviations above normal.


Pereira/Kebede

Day 2
Valid 12Z Sat Oct 04 2025 - 12Z Sun Oct 05 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF=20
FLORIDA'S EAST COAST...

20Z Update...
The Marginal Risk was removed from southeastern Louisiana.
Consensus of the 12Z HREF and 06Z RRFS showed their higher
probabilities for onshore heavy amounts that are associated with a
slow-moving wave remaining confined to the immediate coast and=20
away from the more vulnerable I-10 corridor. Should the models=20
trend back to the north, a Marginal Risk may be reintroduced, but=20
for now the area has been removed from the outlook.

For the Florida East Coast, the signal for widespread showers and
storms, with locally heavy amounts remain. Models have been
generally trending lighter with their QPF. However, with the HREF
still showing some higher probabilities for amounts over 3 inches,
left the Slight Risk centered along the Space/Treasure coasts in
place for now. Also extended the Marginal Risk further south into
the Miami metro, where the hi-res ensembles also show some higher
for amounts over 3 inches.

Previous Discussion...
...Florida's East Coast...

Thunderstorms are expected to continue to develop along the
inverted trough axis oriented north-south along Florida's east
coast on Saturday. Moisture will lift north along with the mid-
level disturbance. The inherited slight and marginal risk areas
were maintained due to a mostly consistent signal for excessive
rainfall over the east central coast. Ensemble exceedance
probabilities of 2 inches are between 5-10% across the marginal
risk area. 48 hour totals between 3-5 inches (local 6") will likely
make overcoming flash flood guidance a bit easier.


Pereira/Kebede

Day 3
Valid 12Z Sun Oct 05 2025 - 12Z Mon Oct 06 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF=20
THE CENTRAL GULF COAST AND THE SOUTHEAST COAST...

20Z Update...

No significant changes were made to the previous outlook.

Previous Discussion...
...Central Gulf Coast...

The mid-level disturbance continues propagating westward toward the
positively tilted upper trough centered over the West on Sunday.
Thus, the heavy rainfall threat will likely bleed over from
Saturday evening into Sunday morning for portions of the Central
Gulf Coast, before dissipating beneath diminished support aloft.
PWATs of 2-2.5" and instability between 500-1000 J/Kg MUCAPE could
churn out rain rates between 1-1.5"/hr Saturday morning into
afternoon. Ensemble exceedance probabilities of 2 inches are
between 5-15% along the far southeastern Louisiana to Florida
panhandle corridor, which supports the marginal risk area in
place.

...Southeast Coast...

Inverted troughing continues along the Florida/Southeast Coast
through the latter part of this weekend. Anomalous moisture (2-3
stndv) will continue interacting with the surface boundary to
generate scattered to isolated thunderstorms across the
Florida/Georgia coast. Rainfall totals of 1-3" are likely along
the Florida/Georgia/South Carolina coast on Saturday. The latest
guidance has trended away from tropical moisture making its way
inland, therefore a marginal risk was maintained for much of the
Southeast Coast.


Pereira/Kebede


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!-kSHFf9FGbEElz7CDUL0IWF94vaj4ZL2TdCZqDLSWmRw= 5cKYQ1bnLI8KZVYDgCgvfzkmuuOyFzpTu9I6x-oMNsNcmEY$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!-kSHFf9FGbEElz7CDUL0IWF94vaj4ZL2TdCZqDLSWmRw= 5cKYQ1bnLI8KZVYDgCgvfzkmuuOyFzpTu9I6x-oMv40Y12o$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!-kSHFf9FGbEElz7CDUL0IWF94vaj4ZL2TdCZqDLSWmRw= 5cKYQ1bnLI8KZVYDgCgvfzkmuuOyFzpTu9I6x-oMWwWDWsE$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 150027
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
827 PM EDT Sun Sep 14 2025

Day 1
Valid 01Z Mon Sep 15 2025 - 12Z Mon Sep 15 2025


...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL IN THE CENTRAL
DAKOTAS...


...Northern Plains...
A northward-moving upper level low brings a southerly flow regime=20
across the Northern Plains, which comes along with ample moisture
-- PW anomalies +2 to +3 sigma. Convergent flow toward the nose of the
sfc- based instability gradient just to the east is expected to=20
promote some south-to- north convection that may overlap areas=20
that saw a few inches of rain on Saturday. Maintained the Slight=20
Risk outline here with a Marginal Risk buffer extending to the=20
south to the edge of the Sand Hills. Few changes were made to the=20
01z update from the 16z update, which resembles the earlier 09z=20
issuance.


...Central and Southern Plains...
Thunderstorms in this region should hang on for a few more hours.
As their coverage is isolated to widely scattered, kept the
associated risk as Marginal. Little change was made to continuity
here.

Roth



Day 2
Valid 12Z Mon Sep 15 2025 - 12Z Tue Sep 16 2025


...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
EASTERN NORTH CAROLINA AND SOUTHEASTERN VIRGINIA...

As a mid-to-upper level low takes shape over the Southeast, the
surface low off of the Southeast Coast is expected to deepen and track
north and then northwest toward the Outer Banks by Tuesday
morning. Models continue to move into better agreement with the
overall track of the system, but show significant spread with
respect to QPF. The general consensus of the 12Z HREF guidance
keeps the heaviest precipitation confined over eastern North
Carolina and far southeastern Virginia, while some other models,
most notably the Canadian Regional and Global, spread heavy
amounts farther west, closer to the mid-level center. Models
generally agree that eastern North Carolina and southeastern
Virginia will become the focus for a strong easterly low level jet
and deepening moisture (PWs increasing to 1.5-2 inches). While the
primary soil types and pre-existing dry conditions may initially
limit the threat for runoff concerns, embedded convection may raise
rainfall rates, resulting in at least isolated excessive runoff,
especially across urbanized areas. Therefore, a Marginal Risk was
introduced. The highlighted area leans closer to the 12Z HREF
consensus and its higher neighborhood probabilities. Probabilities
of amounts exceeding 3 inches are above 50 percent within much of
the risk area. Given the noted uncertainty, adjustments including
an increase in category cannot be ruled out.

Pereira

Day 3
Valid 12Z Tue Sep 16 2025 - 12Z Wed Sep 17 2025


...THERE ARE MARGINAL RISKS OF EXCESSIVE RAINFALL IN SOUTHERN NEW
MEXICO, THE CENTRAL PLAINS, AND COASTAL VIRGINIA/NORTH CAROLINA...

20Z Update...

Broadened the Marginal Risk over southeastern Virginia to also
include portions of northeastern North Carolina. Some models,
including the ECMWF, show additional heavy amounts carrying over
into Day 3 across the region -- which given the anticipation of
heavy amounts impacting this region on Day 3, may prolong runoff
concerns. As on Day 2, continued to lean toward the more easterly
guidance. However, given the uncertainty, additional adjustments
may be forthcoming.

Further west, the upper trough moving across the Rockies has
trended slower. The general consensus of the models shows the axis
of associated precipitation shifting further west, with many of the
models showing their heaviest amounts centered over the flood-resistent Nebraska Sandhills. Therefore, shifted the previous outlook
further west, confining the footprint to the more sensitive areas
from the southern Nebraska Panhandle to northwestern Kansas.

Pereira

Previous Discussion...

...Southern New Mexico...

Moisture will start to nudge upward over southern NM (though much
more well west of there) with some afternoon instability and
expected isolated convection, mainly over the mountains close to
the Mexican border. Low-end Marginal Risk is outlined here though
activity should be rather isolated.

...Central Plains...

Positively-tilted trough over the Northern Rockies will move
eastward to the High Plains Tuesday afternoon. Broad westerly mid-
level flow amid increasing moisture will help fire off some storms
over at least NE near the better forcing but also southward into
KS. A Marginal Risk is outlined here for an isolated flash flood
threat.

...Coastal Virginia...

Over the past couple of days, the models have trended toward
bringing in an area of low pressure near the Outer Banks Tuesday
morning or so. Rain should spread inland on Monday with additional
and perhaps heavier rain on Wednesday. This area has been rather
dry recently and rain rates may not be all that high, but some convection-driven rain is possible depending on the flavor of this
area of low pressure. A Marginal Risk is depicted for
southeastern/coastal Virginia and far northeastern North Carolina
but with a lot of uncertainty in the rainfall
pattern/rates/duration.

Fracasso


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!45sIajUBxn-NuRYiSp6yFiF_595ULNxd3VJtCiijSAWF= LNzEwASk1uOaXHQDpCaOrAFM4Fvbg225qGbWwL6nl55R33o$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!45sIajUBxn-NuRYiSp6yFiF_595ULNxd3VJtCiijSAWF= LNzEwASk1uOaXHQDpCaOrAFM4Fvbg225qGbWwL6nkN8vuno$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!45sIajUBxn-NuRYiSp6yFiF_595ULNxd3VJtCiijSAWF= LNzEwASk1uOaXHQDpCaOrAFM4Fvbg225qGbWwL6nNtbScPg$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 260038
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
838 PM EDT Thu Sep 25 2025

Day 1
Valid 01Z Fri Sep 26 2025 - 12Z Fri Sep 26 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND FAR SOUTHWEST NEW MEXICO, ALONG WITH PARTS OF EASTERN
CALIFORNIA INTO WESTERN NEVADA...

...01Z Update...

...Southwest...

Moisture streaming north around a digging positively tilted trough
has resulting in a corridor of showers and thunderstorms extending
from the AZ/NM/Mexico tripoint north and west to west-central
Nevada. The strongest storms and by far the most prolific flash
flooding are across eastern Arizona into southwestern New Mexico,
where atmospheric moisture levels are their highest. Heavy rain
associated with scattered thunderstorms will likely continue for a
few more hours with daytime heating, then will rapidly diminish in
coverage and intensity after sunset. A similar scenario is also
occurring up north, where a Slight Risk area covers a portion of
the NV/CA border south of Lake Tahoe. In similar fashion as=20
further south, the steady rain will likely persist for another few=20
hours, followed by rapid weakening and dissipation of all=20
precipitation producing showers and storms soon after sunset. The=20
Slight Risk in this area was expanded north to cover some of the=20
flash flooding occurring southeast of Lake Tahoe, but overall a=20
very minor adjustment.

...Northeast...

The inherited Marginal Risk across the Northeast was split with
this update to the area around the OH/WV/PA tripoint and the
northern West Virginia Panhandle, with a second one for much of
southern New England. In the upper Ohio Valley, scattered showers
and storms over southeastern Ohio are moving into an area hard hit
with heavy rain in recent days. Thus, even small amounts of rain in
this terrain may result in renewed flash flooding. Into New
England, a line of moderate to heavy rain is moving into western
New England, and may cause isolated flash flooding in areas that
have seen more rain from the area of rain now moving across Maine,
otherwise the flash flooding threat has largely ended, especially
in most of PA and NY.

...Southeast...

No major changes were made as ongoing clusters of showers and
thunderstorms may still pose an isolated flash flooding threat into
the overnight, though overall coverage should continue gradually
decreasing with the loss of solar heating.

Wegman


Day 2
Valid 12Z Fri Sep 26 2025 - 12Z Sat Sep 27 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND SOUTHWEST NEW MEXICO...

...Southwest...

...2000 UTC Update...
At most, only minor changes made to the Day 2 ERO. Most notably,
we expanded the Slight Risk area slightly westward, which now
includes the Phoenix metro region and is closer to to Prescott and
Flagstaff. This is based on the latest (more elevated_ HREF and
RRFS rainfall exceedance probabilities for Friday afternoon and
evening, especially the probs for 0.50-1.00+ in/hr rainfall, along
with the probs of 3-hourly rainfall exceeding current 3-hour FFG

40% within the Slight Risk area between 20-03Z).

...Previous Discussion...
Numerous showers and thunderstorms are expected across the
Southwest, especially for much of southeastern Arizona and parts of southwestern New Mexico. An upper low should slow to a crawl
across southeast California. Precipitable water values should
remain as high as 1.25-1.5" in spots, but the guidance shows more
potential on the ML CAPE front when compared to Thursday, with
values of 2000-3000 J/kg possible as available moisture interacts
with the cold pool aloft. Widespread shower and thunderstorm
coverage is expected, particularly during the afternoon and evening
hours. A Slight Risk, with a footprint similar to the Day 2 area,
was maintained for Day 3 across parts of Arizona and New Mexico,
but it could be higher end Slight Risk. Hourly rain amounts to 2"
are possible where cells merge and/or train.

...Southeast...
A boundary will remain in place as a cold low forms near the base
of an upper level trough, a feature that lingers for a while near
the Southern Appalachians. Moisture and instability lifting ahead
of the closing system will support periods of showers and storms.
Precipitable water values of up to 2" with ML CAPE to 1000 J/kg
across the Piedmont and 2000-3000 J/kg in coastal areas are
expected, which could yield hourly rain amounts to 2.5" and local
totals to 4".

Roth


Day 3
Valid 12Z Sat Sep 27 2025 - 12Z Sun Sep 28 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF FAR
WEST TEXAS & NEW MEXICO...

...Southwest/Southern Rockies...

...2000 UTC Update...
Expanded the Slight Risk area across NM, particularly northwest
NM, based on the latest (12Z) deterministic and probabilistic
guidance trends with the deepening low eventually cutting over
southeast CA/southwest AZ by Saturday. Model QPFs seem to be
convergence, which is boosting confidence to expand the Slight
farther north toward the NM-CO border. The area also aligns with
where the ECMWF and GFS show highest MUCAPEs (at least 500 J/Kg).

...Previous Discussion...
An upper low remains fixed across the Lower Colorado River while
Gulf Moisture streams into the TX Big Bend and New Mexico, moving
up the Rio Grande. Precipitable water values of 1.25-1.5" are
forecast, which when combined with up to 1000 J/kg of ML CAPE could
yield hourly amounts to 2.5" and local totals to 4" where cells
train and/or merge. Believe the risk level from continuity (Slight)
conveys the risk appropriately at this time for portions of far
west TX and NM. Closer to the upper level center across the
Southwest, slow-moving convection is possible under the cold pool
aloft. Based on the decline of the 1000-500 hPa thickness across UT
towards 5670 meters, limited the northern extent of the Marginal
Risk to southern UT which is about the northern extent of the 0.75" precipitable water value, which was coordinated with the SLC/Salt
Lake City forecast office.

...Carolinas/Southern Mid-Atlantic States...

...2000 UTC Update...
Minimal changes made to the previous Day 3 ERO in this area. Still
cannot rule an upgrade to a Slight Risk somewhere over the Coastal
Plain from SC-VA (see previous discussion); however, the guidance
spread with respect to the QPF remains quite a bit high at this
time to include a targeted Slight Risk area.

...Previous Discussion...
Divergence aloft around the eastern periphery of a cold low near
the Southern Appalachians maintains precipitable water values of
2"+ near the coast, which should also see the greatest instability,
up to 1000 J/kg. The guidance shows a bit of dispersion here in placement/northeast movement of the heavy rain area with the GFS
and NAM in their usual camps (fast and slow, respectively). Hourly
rain amounts to 2.5" and local totals to 4" are expected, similar
to previous days. Forecast uncertainty, as much as anything else,
maintained the risk level as a Marginal. Should the guidance
converge, areas of risk overlap between Friday and Saturday across
portions of the coastal plain of the Carolinas could see an upgrade
to a Slight Risk at some point as we get closer to Saturday.

Hurley/Roth


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!6YmSsLc3Hz2al0zQa0LUEiA65zKbo3NmcArBMC2w4u0j= 6sIEdJQsLJb9ozBTBFysqxBt2hYZ-jgkY4SDI6ZyvOoooXk$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!6YmSsLc3Hz2al0zQa0LUEiA65zKbo3NmcArBMC2w4u0j= 6sIEdJQsLJb9ozBTBFysqxBt2hYZ-jgkY4SDI6ZyZmehpr0$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!6YmSsLc3Hz2al0zQa0LUEiA65zKbo3NmcArBMC2w4u0j= 6sIEdJQsLJb9ozBTBFysqxBt2hYZ-jgkY4SDI6ZyOY64Im8$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 140824
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
424 AM EDT Sun Sep 14 2025

Day 1

Valid 12Z Sun Sep 14 2025 - 12Z Mon Sep 15 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL IN THE WESTERN DAKOTAS...

...Northern Plains...

Upper trough exiting the Rockies has split off its southern=20
portion into an upper low that will move onto the High Plains later
this morning. Southerly flow will continue across the Northern=20
Plains along with ample moisture -- PW anomalies +2 to +3 sigma --=20
as a surface low over SD moves northward later this afternoon.=20
Convergent flow toward the nose of the sfc-based instability=20
gradient just to the east is expected to promote some south-to-=20
north convection that may overlap areas that saw a few inches of=20
rain on Saturday. Maintained the Slight Risk outline here with a=20
Marginal Risk buffer extending to the south to the edge of the Sand
Hills.

...Central and Southern Plains...

Split the longer Marginal Risk area from the previous forecast=20
into its own entity and extended it even farther southward to the=20
Mexican border to account for another tick up in expected=20
convection from KS southward to TX. Storms should fire along and=20
ahead of a low-level confluence axis and within a stripe of deeper=20
moisture. Some of these areas in W TX saw a couple/few inches of=20
rain on Saturday and FFG values are lower. Some models do indicate=20
the potential for slow-moving or backbuilding cells, resulting in=20
locally heavy amounts and perhaps isolated flash flooding concerns.

Fracasso



Day 2

Valid 12Z Mon Sep 15 2025 - 12Z Tue Sep 16 2025

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Fracasso


Day 3

Valid 12Z Tue Sep 16 2025 - 12Z Wed Sep 17 2025

...THERE ARE MARGINAL RISKS OF EXCESSIVE RAINFALL IN SOUTHERN NEW=20
MEXICO, THE CENTRAL PLAINS, AND COASTAL VIRGINIA...

...Southern New Mexico...

Moisture will start to nudge upward over southern NM (though much=20
more well west of there) with some afternoon instability and=20
expected isolated convection, mainly over the mountains close to=20
the Mexican border. Low-end Marginal Risk is outlined here though=20
activity should be rather isolated.=20

...Central Plains...

Positively-tilted trough over the Northern Rockies will move=20
eastward to the High Plains Tuesday afternoon. Broad westerly mid-=20
level flow amid increasing moisture will help fire off some storms=20
over at least NE near the better forcing but also southward into=20
KS. A Marginal Risk is outlined here for an isolated flash flood=20
threat.=20

...Coastal Virginia...

Over the past couple of days, the models have trended toward=20
bringing in an area of low pressure near the Outer Banks Tuesday=20
morning or so. Rain should spread inland on Monday with additional=20
and perhaps heavier rain on Wednesday. This area has been rather=20
dry recently and rain rates may not be all that high, but some=20 convection-driven rain is possible depending on the flavor of this=20
area of low pressure. A Marginal Risk is depicted for=20
southeastern/coastal Virginia and far northeastern North Carolina=20
but with a lot of uncertainty in the rainfall=20
pattern/rates/duration.=20

Fracasso


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!-zq4SVUOyuF5Q6eTNj6cBMaWMMCo-Wv6QPP6fOnPeqSR= rK4P6GV-2eqqJWacjafOPcPbFf7TWsbyulC9wyV2dDqxg8g$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!-zq4SVUOyuF5Q6eTNj6cBMaWMMCo-Wv6QPP6fOnPeqSR= rK4P6GV-2eqqJWacjafOPcPbFf7TWsbyulC9wyV2W7NwOUQ$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!-zq4SVUOyuF5Q6eTNj6cBMaWMMCo-Wv6QPP6fOnPeqSR= rK4P6GV-2eqqJWacjafOPcPbFf7TWsbyulC9wyV2CEZP9G8$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 141950
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
350 PM EDT Sun Sep 14 2025

Day 1
Valid 16Z Sun Sep 14 2025 - 12Z Mon Sep 15 2025


...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL IN THE CENTRAL
DAKOTAS...

16Z Update...

Made only minor adjustments to the previous outlook areas. This
included narrowing the footprint of the Slight Risk area over the
Dakotas. The 12Z hi-res models are in generally good agreement,
indicating a narrow stripe of heavy amounts extending north from
south-central South Dakota to north-central North Dakota. The
Slight Risk reflects the area where the 12Z HREF shows high
neighborhood probabilities for amounts exceeding 3 inches and 5-10
year ARIs.

Pereira

Previous Discussion...

...Northern Plains...

Upper trough exiting the Rockies has split off its southern
portion into an upper low that will move onto the High Plains later
this morning. Southerly flow will continue across the Northern
Plains along with ample moisture -- PW anomalies +2 to +3 sigma --
as a surface low over SD moves northward later this afternoon.
Convergent flow toward the nose of the sfc-based instability
gradient just to the east is expected to promote some south-to-
north convection that may overlap areas that saw a few inches of
rain on Saturday. Maintained the Slight Risk outline here with a
Marginal Risk buffer extending to the south to the edge of the Sand
Hills.

...Central and Southern Plains...

Split the longer Marginal Risk area from the previous forecast
into its own entity and extended it even farther southward to the
Mexican border to account for another tick up in expected
convection from KS southward to TX. Storms should fire along and
ahead of a low-level confluence axis and within a stripe of deeper
moisture. Some of these areas in W TX saw a couple/few inches of
rain on Saturday and FFG values are lower. Some models do indicate
the potential for slow-moving or backbuilding cells, resulting in
locally heavy amounts and perhaps isolated flash flooding concerns.

Fracasso



Day 2
Valid 12Z Mon Sep 15 2025 - 12Z Tue Sep 16 2025


...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
EASTERN NORTH CAROLINA AND SOUTHEASTERN VIRGINIA...

As a mid-to-upper level low takes shape over the Southeast, the
surface low off of the Southeast Coast is expected to deepen and track
north and then northwest toward the Outer Banks by Tuesday=20
morning. Models continue to move into better agreement with the=20
overall track of the system, but show significant spread with=20
respect to QPF. The general consensus of the 12Z HREF guidance=20
keeps the heaviest precipitation confined over eastern North=20
Carolina and far southeastern Virginia, while some other models,=20
most notably the Canadian Regional and Global, spread heavy=20
amounts farther west, closer to the mid-level center. Models=20
generally agree that eastern North Carolina and southeastern=20
Virginia will become the focus for a strong easterly low level jet=20
and deepening moisture (PWs increasing to 1.5-2 inches). While the
primary soil types and pre-existing dry conditions may initially=20
limit the threat for runoff concerns, embedded convection may raise
rainfall rates, resulting in at least isolated excessive runoff,=20
especially across urbanized areas. Therefore, a Marginal Risk was=20 introduced. The highlighted area leans closer to the 12Z HREF=20
consensus and its higher neighborhood probabilities. Probabilities=20
of amounts exceeding 3 inches are above 50 percent within much of=20
the risk area. Given the noted uncertainty, adjustments including=20
an increase in category cannot be ruled out.=20

Pereira

Day 3
Valid 12Z Tue Sep 16 2025 - 12Z Wed Sep 17 2025


...THERE ARE MARGINAL RISKS OF EXCESSIVE RAINFALL IN SOUTHERN NEW
MEXICO, THE CENTRAL PLAINS, AND COASTAL VIRGINIA/NORTH CAROLINA...

20Z Update...

Broadened the Marginal Risk over southeastern Virginia to also
include portions of northeastern North Carolina. Some models,=20
including the ECMWF, show additional heavy amounts carrying over=20
into Day 3 across the region -- which given the anticipation of=20
heavy amounts impacting this region on Day 3, may prolong runoff=20
concerns. As on Day 2, continued to lean toward the more easterly=20
guidance. However, given the uncertainty, additional adjustments=20
may be forthcoming.

Further west, the upper trough moving across the Rockies has
trended slower. The general consensus of the models shows the axis
of associated precipitation shifting further west, with many of the
models showing their heaviest amounts centered over the flood-resistent Nebraska Sandhills. Therefore, shifted the previous outlook=20
further west, confining the footprint to the more sensitive areas=20
from the southern Nebraska Panhandle to northwestern Kansas.

Pereira

Previous Discussion...

...Southern New Mexico...

Moisture will start to nudge upward over southern NM (though much
more well west of there) with some afternoon instability and
expected isolated convection, mainly over the mountains close to
the Mexican border. Low-end Marginal Risk is outlined here though
activity should be rather isolated.

...Central Plains...

Positively-tilted trough over the Northern Rockies will move
eastward to the High Plains Tuesday afternoon. Broad westerly mid-
level flow amid increasing moisture will help fire off some storms
over at least NE near the better forcing but also southward into
KS. A Marginal Risk is outlined here for an isolated flash flood
threat.

...Coastal Virginia...

Over the past couple of days, the models have trended toward
bringing in an area of low pressure near the Outer Banks Tuesday
morning or so. Rain should spread inland on Monday with additional
and perhaps heavier rain on Wednesday. This area has been rather
dry recently and rain rates may not be all that high, but some convection-driven rain is possible depending on the flavor of this
area of low pressure. A Marginal Risk is depicted for
southeastern/coastal Virginia and far northeastern North Carolina
but with a lot of uncertainty in the rainfall
pattern/rates/duration.

Fracasso


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!8pRsiZm5wf4fsGB9HVC5A5m04JVW7wXwUNZDahfh7ARJ= ORN295dcQKML4H_oQqWLH6tDzHfIzdiYyVf2gIxRu89OgHE$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!8pRsiZm5wf4fsGB9HVC5A5m04JVW7wXwUNZDahfh7ARJ= ORN295dcQKML4H_oQqWLH6tDzHfIzdiYyVf2gIxRMXa7a0M$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!8pRsiZm5wf4fsGB9HVC5A5m04JVW7wXwUNZDahfh7ARJ= ORN295dcQKML4H_oQqWLH6tDzHfIzdiYyVf2gIxRLjTIOT0$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 191557
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1157 AM EDT Fri Sep 19 2025

Day 1
Valid 16Z Fri Sep 19 2025 - 12Z Sat Sep 20 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS=20
OF THE SOUTHWEST, UPPER MIDWEST, CENTRAL TO SOUTHEAST KANSAS, AND A
SMALL PORTION OF NORTHWESTERN MISSISSIPPI AND ADJACENT AREAS...

...16Z Update...

...Southwest...

The Slight Risk across a small portion of the Sierras has been
removed with this update. While the northern area of the previous
Slight is still picking up rainfall, rates have been a half inch
per hour or less, and should weaken over the next few hours,
reducing the flooding threat in that area.

A renewed round of showers and thunderstorms across Nevada,
Arizona, and New Mexico may cause additional instances of flash
flooding again this afternoon and evening with peak heating.
Considering the rainfall is over a much larger area as compared to
yesterday, the forcings should be more diffuse and likely more tied
to terrain. Further, the wave of precipitation is continuing to
shear apart as it pushes north and east. A local maximum of
rainfall is noted in the guidance across portions of western and
southern New Mexico, but the signals remain too diffuse to pinpoint
any one area for a Slight Risk upgrade. The area will continue to
be monitored for a possible special upgrade should precipitation
coverage and rates in that area overperform expectations.

...Midwest...

Rainfall around a slow moving low centered near the Minnesota and
Dakotas tripoint has largely been light so far this morning. Expect
stronger convection to break out in some areas this afternoon, with
the low level jet taking over as the primary source of instability
and moisture overnight tonight. Once again there isn't good
agreement on exactly where the heaviest rainfall will occur, but
there's some consensus on the trimmed Marginal area from near
Chicago northwest through the MN/ND/SD tripoint.

...Plains...

A pair of MCS's are expected to impact NE and KS into tonight. The
one in NE has already formed and is moving across the middle of the
state, and is expected to hold together into southeastern Nebraska.
Meanwhile a second one is expected to form in southeast Kansas late
tonight. Considering the flow of moisture and instability from
south to north, the storms to the south should prevent some of the
wetter solutions from materializing with the northern one in
Nebraska. While there is some training potential with both, and
embedded convection may briefly cause higher rain rates with both
MCSs, the higher threat should be with the southern one in Kansas,
so that Marginal remains.

...Mississippi/Tennessee/Arkansas...

Ongoing convection along the Mississippi River into northwestern
Mississippi has been backbuilding and rain cores have been locally
producing 3 inch per hour rainfall rates based on radar data.
Guidance is very poor on the handling of these storms, with most
not recognizing the storms even exist. However, given the high
rainfall rates and the likelihood the storms will persist for at
least a couple more hours based on past behavior, a Marginal Risk
was drawn to cover the flooding potential in this area through the
midday period.

Wegman

...Previous Discussion...

...California/Great Basin...

Remnant energy from Mario will continue to lift north across
California and become sheared by an upstream low over the Pacific,
with some energy wrapping back offshore, while the remainder
moves east into the Great Basin. This energy, along with highly
anomalous moisture (+4 std dev above normal), is expected to
continue to produce showers and storms early in the period across
parts of California, including the Sierra Nevada. While forecast amounts
have trended down, there is still some signal for locally heavy
rain to continue early in the period across portions of the central
Sierra Nevada. A small Slight Risk was maintained, mostly for the
initial 6-hours, where the HREF shows higher probabilities for
additional amounts exceeding an inch. By the afternoon, as the mid
level energy and greater moisture anomalies move east, expect the
greater chance for heavier rain to begin to focus over central
Nevada, where the HREF is showing a broader footprint of high
probabilities for amounts over an inch.

...Southwest...

Expect widespread coverage of showers and storms today, as moisture
from Mario bolsters PWs across the region. The general consensus of
the CAMs show greater coverage across eastern Arizona and western
New Mexico during the afternoon, before storms move southeast into
southeastern New Mexico and West Texas by this evening. Storm
motions are expected to generally progressive, limiting the threat
for widespread heavy amounts and flooding. However, there is some
signal for backbuilding and training, which could raise at least
isolated runoff concerns. HREF neighborhood probabilities for
amounts exceeding an inch are above 50 percent within much of the
Marginal Risk area.

...Upper Mississippi Valley/Midwest to the Lower Missouri Valley...

A mid-to-upper level low/negatively-tilted upper trough will
continue to move slowly east from the northern Plains into the
upper Mississippi Valley this period. While not expected to be a
widespread heavy rainfall event, south-to-north training storms
ahead of the associated occluded front, may produce locally heavy
amounts and isolated flooding from northern Illinois back across
the upper Mississippi Valley. The HREF shows widespread high
probabilities for amounts exceeding an inch across this region,
with some localized high probabilities for amounts over two inches.

Meanwhile, shortwave energy diving southeast out of the northern
High Plains, is expected to produce a secondary area of organized
amounts, with some locally heavy amounts possible from
southeastern Nebraska into southwestern Iowa and northwestern
Missouri this evening into the overnight. Here also, the HREF is
showing high probabilities for amounts over an inch, with heavier
amounts possible.

...Central Plains...

Energy moving through the base of the previously noted upper
trough, interacting with deepening moisture along a strengthening
low level jet is expected produce showers and storms developing
and dropping southeast across Kansas, with locally heavy amounts
possible by this evening. HREF probabilities indicate localized
amounts of an inch or more are likely, with heavier amounts
possible.

Pereira

Day 2
Valid 12Z Sat Sep 20 2025 - 12Z Sun Sep 21 2025


...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF SOUTHEASTERN KANSAS AND NORTHEASTERN OKLAHOMA THROUGH THE
OZARKS...

Storms developing late in the previous period across Kansas may
continue, producing locally heavy amounts across portions of the
Ozark Region Sunday morning. Redevelopment is possible back to the
west later in the day as shortwave energy emanating from the west
moves into the region and interacts with deepening moisture
afforded by strengthening southerly flow.

Pereira

Day 3
Valid 12Z Sun Sep 21 2025 - 12Z Mon Sep 22 2025


...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE SOUTHWEST AND FROM THE OZARKS THROUGH THE MID MISSISSIPPI
VALLEY...

...The Southwest...

An upper low off of the California coast will drift southeast,
supporting the return of deeper moisture spreading north across
Arizona and western New Mexico on Sunday. With PW anomalies
increasing to 2-3 standard deviations above normal, numerous showers
and storms, producing locally heavy rainfall amounts and isolated
flooding concerns, can be expected.

...Ozarks through the Mid Mississippi Valley...

A broad upper trough will drift slowly east from the Plains into
the Mississippi Valley this period. A series of mid level
shortwaves lifting along the leading edge of the trough,
interacting an axis of deeper moisture is expected to produce showers
and storms with periods of heavy rainfall possible.

Pereira


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!5aaCviy4I5IFWrGEYPTpv0hxy6bLFUxtYpcRX0IRWQV8= sMKmL9SsAbLGC0hn4Yw3mLa2j1NQuxXJQNwxyYg8fjXkX64$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!5aaCviy4I5IFWrGEYPTpv0hxy6bLFUxtYpcRX0IRWQV8= sMKmL9SsAbLGC0hn4Yw3mLa2j1NQuxXJQNwxyYg8Vvnp5dg$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!5aaCviy4I5IFWrGEYPTpv0hxy6bLFUxtYpcRX0IRWQV8= sMKmL9SsAbLGC0hn4Yw3mLa2j1NQuxXJQNwxyYg8hKS0UcM$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 231554
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1154 AM EDT Tue Sep 23 2025

Day 1
Valid 16Z Tue Sep 23 2025 - 12Z Wed Sep 24 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHERN
MISSOURI, FAR SOUTHEAST KANSAS, EASTERN OKLAHOMA, FAR NORTHEAST
TEXAS, ARKANSAS, WESTERN TENNESSEE, WESTERN KENTUCKY, AND SOUTHERN
ILLINOIS AND SOUTHERN INDIANA...

...Lower Arkansas Valley, Lower Mississippi Valley into the Lower
Ohio Valley...

16Z Update: No significant changes to the risk areas with the main
area of concern being southern Missouri, northern Arkansas, eastern
Oklahoma, and far southeast Kansas where a frontal boundary draped
across interacts with copious amounts of moisture. The 12Z HREF
probabilities align fairly well with the inherited Slight Risk=20
area with only minimal adjustments needed.=20

---previous discussion---=20

The strengthening low level southerly flow/anomalous 850-700 mb
moisture flux that have supported organized convection over the
Central to Southern Plains early Tuesday will continue to support
the downstream push of this organized convection post 1200 UTC,
with these anomalous 850-700 mb moisture flux values of 2-3+
standard deviations above the mean moving from the eastern sections
of the Southern Plains into the Lower AR Valley, Lower MS, TN and
OH Valleys. There continues to be some north south spread in the
models with respect to the position of the max precip axis.
Generally, the non-CAMs are farther north and the CAMs farther
south. WPC continues to support the farther south qpf solutions,
with our day 1 risk areas drawn toward them. Overall, not a lot of
changes to the previous slight risk areas. We did extend the slight
risk farther east into the Lower OH Valley where there is expected
to be overlap of day 1 heavy precip with observed precip over the
past 24 hours. We also extended the slight risk area farther south
into northeast TX where several of the new 0000 UTC hi-res runs and subsequently the new HREF mean show heavy precip. Otherwise, the
slight and 25% areas fit well with where the HREF and RRFS
neighborhood probabilities are high day 1 for 2" and 3+ amounts.


...Coastal Central California...
There continues to be good model agreement with the nearly
stationary closed low off the Southern CA coast beginning to
slowly move back to the north on day 1 toward the Central CA
coast. This slow north movement will also allow for a northward
expansion of the anomalous PW values over Southern CA into coastal
Central CA, with values as high as 3-4 standard deviations above
the mean. With good model agreement on the closed low track day 1,
there is also good agreement on potential for areal average
moderate precip totals, with potential for locally heavier amount
along the Central CA coast. Isolated runoff issues are possible,
especially over any burn scars.

...New Mexico...
The combination of upper level divergence bringing large scale
forcing for ascent along with an axis of slightly above normal
moisture will bring the threat of isolated to scattered
thunderstorms to the area. A Marginal Risk was introduced for the
threat of isolated flash flooding, particularly over any sensitive
areas like recent burn scars.=20

Oravec/Taylor

Day 2
Valid 12Z Wed Sep 24 2025 - 12Z Thu Sep 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE
TENNESSEE AND OHIO VALLEY REGIONS...

Anomalous PW and 850-700 moisture flux values will stretch across a
large area from the Lower MS Valley, and into the TN & OH Valleys,
Central Appalachians and the Mid-Atlantic, ahead of the amplifying
longwave trof stretching from the Great Lakes, southward into the
Lower MS Valley. There still is a fair amount of qpf spread with
the max axis day 2. WPC is leaning more toward the multi model
ensemble qpf mean/NBM to drive our qpf and excessive rainfall
axes. This will support a widespread axis of moderate to heavy
precip amounts from eastern TX into the Lower MS Valley, TN and OH
Valleys. While a large portion of the day 2 QPF and ERO axes are
currently in moderate to severe drought, there may be overlap in
qpf areas from day 2 and what has fallen over the past 24 hours
from eastern TN into central to eastern KY, and the Upper OH Valley
region. The previous slight risk was narrowed to better fit this
potential overlap areas. The marginal risk was also trimmed
significantly from southern L.P. of MI, IL, southeast MO and AR to
better fit the latest qpf update.

...Central California...
The slow moving closed low approaching the central CA coast late
day 1 will continue to push slowly eastward day 2 and push inland
by early Thursday morning. Similar to the day 1 period, an axis of
anomalous PW values, 2 to 3 standard deviations above the mean,
will persist to the east northeast of the closed low across Central
CA. Scattered convection in this anomalous PW axis will support
locally heavy rains across Central CA and isolated runoff issues,
especially across burn scar regions.

...Far southeast Arizona into New Mexico...
No changes made to the previous marginal risk area across this
region. Scattered convection possible, with localized heavy rain
and isolated runoff issues, especially in burn scar regions.

Oravec

Day 3
Valid 12Z Thu Sep 25 2025 - 12Z Fri Sep 26 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND FAR SOUTHWEST NEW MEXICO...

The slow moving closed low moving inland into Central CA day 2 will
drop back to the south southeast toward Southern CA day 3. This
system will continue to have an area of anomalous PW values in the
vicinity of the upper center across Central CA into the Great
Basin. This closed low will also begin to tap anomalous PW values
over northwestern Mexico, transporting them into southeast Arizona
day 3. Model consensus is for a max precip area over Southeast
Arizona and far southwest New Mexico. The previous slight risk
across this area was only modified slightly, expanding it slightly
to the north and east to cover the model max qpf spread. Only some
minor changes to the marginal risk to the northwest of this across
northern AZ, southern NV, far southwest UT and into the central
Sierra. Locally heavy rains and isolated runoff issues possible
across these areas, especially over burn scars.

...Southern to Central Appalachians...
There will continue to be a broad axis of above average PW values
pushing eastward day 3 ahead of the elongated upper trof
stretching from the Great Lakes into the OH and TN Valleys. There
is a lot of qpf differences in this high PW axis, leading to low
confidence in where to put risk areas. Much of the eastern U.S. is
in drought conditions with low relative soil moisture levels. One
exception is over portions of the Southern to Central Appalachians
from eastern TN/far western NC/far southwest VA and eastern WV.
Kept the day 3 marginal confined to these areas and removed the
broader marginal from the previous issuance that extended north and
east into the Mid-Atlantic and southwestward to the Gulf Coast.


Oravec

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!8HoWOi37BSa4wePhgYbJqOTQ5T6Zw7VBD5qIkNCFtsR3= qrGD81y0M4rM_nssEOiAkMMvayQEvR1yY6CHkD3S3sh9Itw$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!8HoWOi37BSa4wePhgYbJqOTQ5T6Zw7VBD5qIkNCFtsR3= qrGD81y0M4rM_nssEOiAkMMvayQEvR1yY6CHkD3S_5foOx0$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!8HoWOi37BSa4wePhgYbJqOTQ5T6Zw7VBD5qIkNCFtsR3= qrGD81y0M4rM_nssEOiAkMMvayQEvR1yY6CHkD3Sc7YbA7I$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 250046
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
846 PM EDT Wed Sep 24 2025

Day 1
Valid 01Z Thu Sep 25 2025 - 12Z Thu Sep 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR THE OHIO=20
VALLEY AND PORTIONS OF SOUTH TEXAS...

...01Z Update...

...Ohio and Tennessee Valleys...

Rain associated with a pair of disturbances is developing across
the lower Ohio Valley this evening. The locally heavy rain
associated with embedded convection will spread northeast up the
Ohio Valley, where rain from recent days has moistened the soils
somewhat. Thus, the Slight Risk was adjusted north, but remains in
place for the potential for widely scattered instances of flash
flooding. Further south into the Tennessee Valley the rain is
generally more progressive, less widespread, and there are large
areas with no rain occurring. Those areas have been dropped down to
a Marginal with this update.

...South Texas...

Developing convection along a cold frontal interface is expected to
become more widespread overnight, though model agreement on how
that convection behaves once formed is poor. The frontal interface
will likely be where the most persistent convection forms and
remains before likely pushing south into the heat and instability
in place across Deep South Texas. Thus, the rather narrow corridor
from Corpus Christi on the coast to Laredo on the Rio Grande is=20
likely where the highest chances for flash flooding will be through
tonight.

Wegman


Day 2
Valid 12Z Thu Sep 25 2025 - 12Z Fri Sep 26 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND FAR SOUTHWEST NEW MEXICO...

...Southwest to Sierra Nevada...

After moving inland early Thursday, the closed low over central
California is forecast to drop south into southern California by
early Friday. With ample moisture remaining in place (2-3 std
dev above normal) near and east of the upper center, locally heavy
amounts are possible from the Sierra Nevada east into southern
Nevada and southwestern Utah.

As the center drops south, increasing southerly flow east of the
low will draw deeper moisture up from Mexico, fueling widespread
shower and thunderstorm coverage, especially across southeastern
and central Arizona into southwestern New Mexico. A Slight Risk
was maintained across this area where PWs are forecast to increase
to 1-2 standard deviations above normal by the afternoon.

...Northeast...

Unsettled weather developing Day 1 is forecast to continue into
Thursday as showers and storms continue to develop ahead of the
system lifting out of the Ohio Valley into the Northeast.
Strengthening southwesterly flow along the Mid Atlantic coast into
the Northeast will support deepening moisture (PWs increasing to ~2
inches) and an increasing threat for heavy rainfall rates. A
Marginal Risk was maintained from northern New Jersey into southern
New England, where HREF probabilities indicate that localized
amounts over 3 inches are possible late Thursday morning into the
afternoon.

...Southern Appalachians into parts of the Southeast and Eastern
Gulf Coast...

...2000 UTC Update...

Amplifying mid-upper trough digging into the northwest and north-
central Gulf Thu-Thu night will slow the eastward progression of
the surface cold front and thus favorable pre-frontal buoyant
airmass (ribbon of higher TPW and deep-layer instability). More
protracted period of favorable low-level moisture transport ahead
of the upper trough/surface front. 12Z HREF probabilities depict
this idea well, with several hours of spotty areas with enhanced
probs for 1-2+ in/hr rainfall rates. Therefore, supported by the
latest CSU UFVS-verified ERO First-Guess field, have expanded the
Marginal Risk south to the MS-AL-western FL Panhandle Gulf Coast.


...Previous Discussion...

The consensus of the latest guidance indicates that showers and
storms developing along and ahead of the cold front trailing the
low moving through the Northeast will be generally progressive.
With widespread heavy amounts not expected and FFGs high, the
previous Marginal Risk was removed from much of the Mid Atlantic.
However, some models do show the potential for training storms to
produce some localized heavy amounts (2+ inches) across parts of
the southern Appalachians, where a small Marginal Risk was
maintained.

Hurley/Pereira


Day 3
Valid 12Z Fri Sep 26 2025 - 12Z Sat Sep 27 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND SOUTHWEST NEW MEXICO...

...Southwest...

A second day of numerous showers and storms is expected across the
Southwest, especially for much of southeastern Arizona and parts of southwestern New Mexico. The upper low setting into southern
California the previous period is expected to move little this day,
remaining centered near the California/Mexico border. This will
help to maintain anomalous moisture across the region, fueling
widespread shower and thunderstorm coverage during the afternoon
and evening hours. A Slight Risk, with a footprint similar to the
Day 2 area, was maintained for Day 3 across parts of Arizona and
New Mexico.

...Southeast...

A boundary will remain in place across the Southeast as an upper
trough evolves into a closed low that is forecast to linger beyond
the period. Moisture and energy lifting ahead of the closing system
will support periods of shower and storms. While the guidance at
this point is not signaling any widespread heavy amounts, the
pattern does lend itself to at least the threat for locally heavy
amounts, which may raise at least isolated flooding concerns.

Pereira

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!4QDYoBFeNMOd1Ld9bCQPgYzlRQX5emLDwLwCBoyFY48R= Clcn8tnCyqBzBMMpEAOMrOQUBya-8ZfpL6lqWvLjXgO07DA$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!4QDYoBFeNMOd1Ld9bCQPgYzlRQX5emLDwLwCBoyFY48R= Clcn8tnCyqBzBMMpEAOMrOQUBya-8ZfpL6lqWvLjv9146VM$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!4QDYoBFeNMOd1Ld9bCQPgYzlRQX5emLDwLwCBoyFY48R= Clcn8tnCyqBzBMMpEAOMrOQUBya-8ZfpL6lqWvLjPA8nWGM$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 262026
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
426 PM EDT Fri Sep 26 2025

Day 1
Valid 16Z Fri Sep 26 2025 - 12Z Sat Sep 27 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE SOUTHWEST & IN THE VICINITY OF THE CAROLINAS...

16z Update: Not many changes needed to the inherited outlook from
earlier this morning. Central to southern AZ remains the focus for
potentially locally significant flash flooding. Pretty impressive
southerly inflow/moisture transport combined with upwards of 2000
J/KG of CAPE will support a backbuilding convective threat today.
Main question will be how much of this moves off the terrain and
towards the Phoenix to Tuscon urban corridor. The initial tendency
will be for convection to focus in the terrain areas, likely
growing in coverage and intensity. If a strong enough outflow can
push south out of this activity then we could see convection move
off the terrain and into the lower elevations/urban areas. If this
happens the strong southerly flow will support
backbuilding/training and an increased flash flood risk. HREF and
REFS probabilities support 2-4" rainfall totals where this training
is able to persist. However still unclear whether these totals are
able to move southward out of the higher terrain...but there is
certainly some potential for this scenario.

Chenard

...Previous Discussion...

...Southwest...
Numerous showers and thunderstorms are expected across the
Southwest, especially for much of southeastern Arizona and parts of southwestern New Mexico, which should occur primarily during the
afternoon and evening hours. An upper low should slow to a crawl
across southeast California. Precipitable water values should
remain as high as 1.25-1.5" in spots. ML CAPE values of 2000-3000
J/kg are possible as available moisture interacts with the cold
pool aloft. A Slight Risk was maintained across parts of Arizona
and New Mexico, but it could be higher end Slight Risk. Hourly rain
amounts to 2" with local totals to 4" are possible where cells
merge and/or train.


...Southeast...
A boundary will remain in place as a cold low forms near the base
of an upper level trough, a feature that lingers for a while near
the Southern Appalachians. Farther inland across the Piedmont, some
degree of upslope flow should bring some of the higher moisture
back in from the southeast. Moisture and instability lifting ahead
of the closing system will support periods of showers and storms.
Precipitable water values of up to 2" with MU CAPE of 1000+ J/kg
across the Piedmont and 2000-3000 J/kg in coastal areas are
expected, which could yield hourly rain amounts to 2.5" and local
totals to 4". As the 00z HREF and 18z REFS had their strongest
signal for 3"+ and 5"+ across far southwest VA and the western
Carolinas, a Slight Risk was added in this update, which was
coordinated with the local offices. For the time being, a Slight
Risk was left out across the coastal plain of the Carolinas as
recent dryness could make a higher incidence of flash flooding
harder to come by, which was coordinated with the coastal Carolina
offices.

Roth


Day 2
Valid 12Z Sat Sep 27 2025 - 12Z Sun Sep 28 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE SOUTHWEST AND MID ATLANTIC TO SOUTHEAST...

20z Update: The Slight risk was maintained over the Mid Atlantic
with this update. The higher confidence for potential flash=20
flooding appears to be over portions of central to southeast VA.=20
This is in the vicinity of the stationary front where lower level=20 convergence should be maximized. Instability will drop off with=20
northern extent, however we should have enough instability along=20
and just north of the front to support an axis of low topped=20
convection. This activity will likely be warm rain dominant, and=20
thus efficient at producing heavy rainfall rates. The exact axis=20
remains a bit uncertain, with model solutions varying from near=20
the NC/VA border on the southern side, to DC on the northern=20
extent. At the moment the best clustering is around Richmond, but=20
there is some opportunity for that to shift a bit north or south.=20
Where this axis does set up, localized rainfall over 4" appears=20
likely. The Slight risk was expanded a bit northward over central
and eastern VA to account for this risk.

Confidence is lower on the Slight risk farther south over NC and=20
SC. Certainly plenty of moisture in place, but the coverage and=20
organization of convection is less clear. Also a possibility that=20
the cells that do form tend to move along at a fast enough clip to=20
limit the flash flood coverage. The best chance of some training=20
could be along the coastal corridor where convergence and=20
instability may be a bit stronger. Overall the flash flood risk=20
over these areas may end up staying more isolated in nature...but=20
the potential for greater coverage is still there, and so we will=20
maintain the recently introduced Slight risk area.

Over the Southwest a Slight risk area was added to portions of=20
southeast CA into southwest AZ. The upper level low will remain=20
over these areas on Saturday providing broad ascent for convective=20 development. Instability over these areas is forecast to be=20
greater Saturday than Friday, and PWs will remain well above late=20
September averages. Thus would expect to see greater convective=20
coverage than today, with heavy rainfall rates likely. The presence
of the upper low should support slow cell motions and the=20
potential for periodic cell mergers.

Chenard

...Previous Discussion...

...Southwest/Southern Rockies...
An upper low remains fixed across the Lower Colorado River while
Gulf Moisture streams into the TX Big Bend and New Mexico, moving
up the Rio Grande. Precipitable water values of 1.25-1.5" are
forecast, which when combined with 1000+ J/kg of ML CAPE could
yield hourly amounts to 2.5" and local totals to 4" where cells
train and/or merge. Believe the risk level from continuity (Slight)
conveys the risk appropriately at this time for portions of far
west TX and NM. Closer to the upper level center across the
Southwest, slow-moving convection is possible under the cold pool
aloft, with ML CAPE of 1000-2000 J/kg of instability and
precipitable water values in the Lower Desert of 1-1.25" expected.
Based on the decline of the 1000-500 hPa thickness across UT
towards 5670 meters, limited the northern extent of the Marginal
Risk to southern UT which is about the northern extent of the 0.75" precipitable water value.


...Carolinas/Southern Mid-Atlantic States...
Divergence aloft around the eastern periphery of a cold low near
the Southern Appalachians and what is now a tropical disturbance
moving through the Bahamas as a possible tropical cyclone on
Saturday team up to maintain precipitable water values of up to
2.25" across the coastal plain, which should also see the greatest
instability, 1000-2000 J/kg. The Piedmont should see times when the
MU CAPE rises above 500 J/kg. This is a PRE-like set up for the
region, so the heavy rainfall potential has a higher upside than
usual. There has been some convergence in the model guidance QPF-
wise, and both the 00z HREF and 18z REFS had a cohesive and
agreeable enough heavy rain threat of 3"+ for a new Slight Risk
area from roughly Richmond VA south on both sides of the fall line
into eastern SC. Hourly rain amounts to 3" and local totals to 6"
are possible, which is potentially problematic anywhere within the
Slight Risk area. A higher risk level can't be ruled out in future
updates.

Roth



Day 3
Valid 12Z Sun Sep 28 2025 - 12Z Mon Sep 29 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF FAR
WEST TEXAS AND NEW MEXICO...

20z Update: We did opt to remove the small Slight risk along the
SC/NC coast with this update. Most guidance suggests the heaviest
rainfall this period will remain offshore, with greater impacts
onshore beginning on day 4 (Monday into Tuesday). There is
certainly some potential for locally heavy rain along coastal
areas, but at the moment the risk appears localized in nature.=20
Thus a Marginal risk should be enough to cover this threat for=20
now and we will continue to monitor trends.

Little to no change was needed over the Southwest with this=20
update. Portions of NM into far west TX still look on track for an=20
isolated to scattered flash flood risk as mid/upper level=20
troughing moves eastward.

Chenard

...Previous Discussion...

Southwest/Southern Rockies...
The combination of an upper low moving to near the Four Corners, a
kicker upper level trough moving into CA, and moisture feed from
the Gulf into NM persist into Sunday. Precipitable water values
remain above 1" locally in the Desert Southwest and 1-1.25" in the
Southern High Plains. Pockets of 1000+ J/kg of ML/MU CAPE are
forecast to develop and/or persist. A Slight Risk still appears
reasonable across portions of far west TX and NM, with a broader
Marginal Risk surrounding that. The guidance appears to be trending
somewhat drier across the Great Basin, so limited the northern
extent of the Marginal Risk area when compared to continuity.


Florida northward into the Southern Mid-Atlantic States...
A system now considered a tropical disturbance over Hispaniola
should lie somewhere north of the Bahamas and east of Florida as a
possible tropical or hybrid cyclone on Sunday. The upper level
environment doesn't look kind for whatever emerges, and there are
two scenarios -- a more convective system that remains offshore
during the medium range period or a more sheared system that
attempts to occlude when it approaches landfall early next week.
The guidance is not ideal in differentiating which is correct
during these scenarios, historically.

Regardless, moisture will not be a problem regionally --
precipitable water values locally 2"+. Coastal areas will see
1000+ J/kg of ML CAPE while 250+ J/kg of MU CAPE invades portions
of VA. The guidance has slowed down the approach of the tropical
low since yesterday, but the other players in the flow pattern
remain -- the upper low near the southern Appalachians/southern
Cumberland Plateau and the front near the East Coast. A PRE- like
set up appears to be in the cards, with moisture streaming into the
front from the south. The best signal for heavy rainfall on Sunday
into early Monday appears to be in the vicinity of Myrtle Beach,
and considering previous days of rain, thought a new Slight Risk in
that area would be prudent. In theory, hourly rain amounts to 3"
should be possible, which would be most problematic should
thunderstorms merge or train.

Roth


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!8D-yRoqOmKEr3QqccSN0O-qwsJwkziezGu4czyd0yK3z= sMFdgvHwMhSdW5Z4oFnVwB6XT_-nxe05Uz-V0O9rWs9EfOs$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!8D-yRoqOmKEr3QqccSN0O-qwsJwkziezGu4czyd0yK3z= sMFdgvHwMhSdW5Z4oFnVwB6XT_-nxe05Uz-V0O9r3eepMfc$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!8D-yRoqOmKEr3QqccSN0O-qwsJwkziezGu4czyd0yK3z= sMFdgvHwMhSdW5Z4oFnVwB6XT_-nxe05Uz-V0O9rn4REM70$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 280057
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
857 PM EDT Sat Sep 27 2025

Day 1
Valid 01Z Sun Sep 28 2025 - 12Z Sun Sep 28 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE SOUTHWEST...

...Southwest...
A Slight risk was maintained across portions of southeast CA into
western AZ. Isolated to scattered instances of flash flooding
continue this evening. Still generally expect to see the coverage
and intensity of convection decrease overnight, although with
lingering instability and the mid level low overhead we could see
at least some localized areas of heavier convection continue.

The Slight risk was removed over NM with this update. Still expect
to see some convection overnight, and localized instances of flash
flooding are still possible. However, activity has generally=20
underperformed so far today, and with instability lower here=20
compared to farther west, generally think the flash flood risk is=20
isolated enough to warrant just the Marginal risk.

...East Coast...
A Marginal risk was maintained in the vicinity of the Delmarva
where low topped convection will support efficient warm rain
processes. Overall not expecting much in the way of a flood=20
threat, but heavy rates could result in a localized risk.

Slow moving convection near the mid/upper vort energy will
continue to support an isolated flash flood risk over portions of=20
southwest VA and central NC. Overall the expectation is for this=20
activity to decrease in coverage/intensity going forward...but=20
models have not had a great handle on this convection and thus=20
another instance or two of flash flooding can not be ruled out.

Increasing easterly flow well north of Tropical Depression Nine=20
may help locally enhance convergence along the east coast of FL=20
tonight into Sunday morning. Low confidence on these details, but=20
if heavier convection is able to develop then a localized urban=20
flash flood risk is a possibility.

Chenard


Day 2
Valid 12Z Sun Sep 28 2025 - 12Z Mon Sep 29 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
FAR WEST TEXAS AND NEW MEXICO...

...Great Basin through the Southern Rockies...
The closed low over the Low Deserts on D1 will gradually open and
fill during Sunday while meandering slowly northeast such that the
primary trough axis is positioned over the Four Corners by 12Z
Monday. Despite this weakening, pronounced height falls and
periodic PVA from weak embedded impulses will maintain broad ascent
from the Great Basin through the Southern Rockies. At the same
time, downstream southerly flow ahead of the trough axis will
continue to manifest as a surge of elevated PWs, with widespread PW
anomalies from the NAEFS reaching the 97th to 99th percentiles.

This broad southerly flow combined with the lowering heights aloft
will also produce elevated MUCAPE of 500-750 J/kg across most of
this area, with locally enhanced instability above 1000 J/kg over
NM. This setup will support scattered to widespread convection as
suggested by available CAMs simulated reflectivity, with rain rates
potentially reaching 1"/hr at times. Mean 0-6km winds Sunday should
again be steady out of the south at 10-15 kts, although aligned
propagation vectors could result in some repeating/training,
especially across New Mexico. The inherited risk areas were
adjusted for new guidance, but changes were primarily cosmetic.


...Southeast Coast...
Concern on Sunday turns towards Tropical Depression Nine and its
evolution as it starts to lift slowly northward from the Bahamas
while strengthening. While there continues to be quite a bit of
model uncertainty, the general model trends have been for a slower
progression of this system, with very dry air likely positioned
just to its west as reflected by 750-500mb RH fields.

This suggests that precipitation may be a bit slower to move
onshore from the FL Peninsula into the Carolinas, but as Nine
deepens and the subsequent 850mb winds to the north intensify, the
accompanying strengthening cyclonic flow will transport impressive
tropical moisture westward and onshore, with PWs likely reaching
above 2" from Cape Fear southward through the Space Coast. As
tropical rain showers move onshore, they will be extremely
efficient, with rain rates likely reaching 2-3"/hr. These showers
will repeatedly generate offshore and then train onshore, so right
along the immediate coast where sufficient instability and
moistening can occur, total rainfall could exceed 3", especially
across Florida, as reflected by HREF probabilities exceeding 40%.
Of course, any additional trends west or slower in the track of
Nine could enhance this rainfall, and locally higher totals are
expected.

The inherited MRGL risk was trimmed closer to the coast, especially
across the Carolinas, with this update, with additional, but
minimal cosmetic adjustments over the Florida Peninsula also made
with this update.


Weiss

Day 3
Valid 12Z Mon Sep 29 2025 - 12Z Tue Sep 30 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE COASTAL
PLAIN FROM NORTH CAROLINA THROUGH THE CENTRAL FLORIDA PENINSULA...

...Southeast and Mid-Atlantic...
All attention will be on Tropical Depression Nine, which is
forecast by NHC to be a strong Tropical Storm or Cat 1 Hurricane on
Monday as it lifts slowly northward from the Bahamas. While
guidance has been slowly converging on a solution that brings the
storm to a stall east of the GA/SC coast by the end of D3, there is
still considerable spread in the ensembles. Staying close to the
NHC track brings heavy rainfall D3 from the Space Coast of Florida
northward into Southeast North Carolina. The exact track and
intensity of Nine will determine where the greatest moisture
convergence will occur to create the heaviest rainfall amounts, but
anywhere along and north of the track will likely receive training
tropical showers with 2-3"/hr rain rates. The heaviest rain still
appears to be confined to the immediate coast due to dry air to the
west, but as the column slowly saturates in response to persistent
and increasing moist advection on strengthening onshore 850mb flow,
heavy rain will eventually spread inland, especially into SC and
NC. While the inherited SLGT risk was trimmed to the south a bit
over NC and expanded along the eastern coast of the FL Peninsula
with this update, in general, changes were minimal due to
continuing track uncertainty.


...Northern California/Southwest Oregon...
An impressive trough will push eastward across the Pacific Monday,
reaching the coast and angling onshore by 12Z Tuesday. This will
drive a frontal system onshore, and the resulting low-level
convergence overlapped by a modestly coupled jet structure will
provide plentiful ascent for heavy rainfall along the coast of
northern CA/southern OR D3. Moisture transport will become
impressive ahead of the front as reflected by high probabilities
(70-80%) for IVT exceeding 500 kg/m/s from both the ECENS and GEFS
ensembles, pushing PWs to above 1 inch on increasing southerly
850mb inflow. Where this moisture overlaps with sufficient
instability (progs suggest at least 250 J/kg MUCAPE) it will result
in periods of moderate to heavy rainfall with rates of
0.25-0.5"/hr which may be sufficient for at least localized impacts
in vulnerable terrain, especially where training or enhanced
convergence along terrain features can produce more than 1 inch of
rainfall.


Weiss


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!-6rocvidYNaM1uOSopYxalkmeDx6R8ZniWv4HMxaBGi0= UHiWneK-G6emfOSJa5NE-UMoQlkYTc4XHkMuVF1yUL4CsZQ$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!-6rocvidYNaM1uOSopYxalkmeDx6R8ZniWv4HMxaBGi0= UHiWneK-G6emfOSJa5NE-UMoQlkYTc4XHkMuVF1yoj88jXE$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!-6rocvidYNaM1uOSopYxalkmeDx6R8ZniWv4HMxaBGi0= UHiWneK-G6emfOSJa5NE-UMoQlkYTc4XHkMuVF1yu09dmxA$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 030743
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
343 AM EDT Fri Oct 3 2025

Day 1
Valid 12Z Fri Oct 03 2025 - 12Z Sat Oct 04 2025

...THERE'S A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
FLORIDA'S EAST COAST...

...Florida's East Coast...

A closed mid-level disturbance will drift westward across the=20
Florida Peninsula and into the Gulf of Mexico today. This system
will bring tropical moisture from Imelda and Humberto with it. An=20
inverted trough oriented along the Florida coast will interact with
the moisture advecting into the region and force scattered=20
thunderstorm activity throughout the day. Modest instability=20
between 500-1000 J/Kg MUCAPE could produce quarter to half inch=20
rates over the slight risk area. Parts of central and southern=20
Florida that have received between 2-4 (isolated 5) inches of rain
in the past 24 hours will be especially susceptible to runoff from
today's storms. Neighborhood exceedance probabilities of 5 inches=20
are between 20-40% across Florida's east coast today.

...Great Basin...

Additional rainfall is forecast to occur beneath the upper low,
which will continue propagating through the interior West today.=20
Recent heavy rainfall over portions of the Great Basin will likely
prime surfaces for runoff from additional precipitation. Burn=20
scars in central and southern Idaho continue to be of concern from=20
today's storms, the bulk of which should occur this morning into=20
afternoon before the upper low moves directly over the Great Basin=20
and instability weakens. HREF EAS exceedance probabilities of over=20
1 inch are between 15-35% over northern/central Nevada where PWATs=20
will be between 2-3 standard deviations above normal.


Kebede

Day 2
Valid 12Z Sat Oct 04 2025 - 12Z Sun Oct 05 2025

...THERE'S A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
FLORIDA'S EAST COAST...

...Florida's East Coast...

Thunderstorms are expected to continue to develop along the=20
inverted trough axis oriented north-south along Florida's east=20
coast on Saturday. Moisture will lift north along with the mid-
level disturbance. The inherited slight and marginal risk areas=20
were maintained due to a mostly consistent signal for excessive=20
rainfall over the east central coast. Ensemble exceedance
probabilities of 2 inches are between 5-10% across the marginal
risk area. 48 hour totals between 3-5 inches (local 6") will likely
make overcoming flash flood guidance a bit easier.

...Central Gulf Coast...

The same moisture regime impacting the Florida peninsula will focus
over the central Gulf Coast this weekend. Mid-level vorticity will
lift into the area on Saturday, providing forcing for convection=20
along the immediate Louisiana/Mississippi coast. Anywhere between=20
4-6 inches of rain may occur over far southeastern Louisiana=20
through Saturday night. Despite 2" ensemble exceedance=20
probabilities being relatively low (5-10%), the multi day nature=20
of the rainfall could still produce isolated instances of flash=20
flooding.


Kebede

Day 3
Valid 12Z Sun Oct 05 2025 - 12Z Mon Oct 06 2025

...THERE'S A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE CENTRAL GULF COAST AND THE SOUTHEAST COAST...

...Central Gulf Coast...

The mid-level disturbance continues propagating westward toward the
positively tilted upper trough centered over the West on Sunday.
Thus, the heavy rainfall threat will likely bleed over from=20
Saturday evening into Sunday morning for portions of the Central=20
Gulf Coast, before dissipating beneath diminished support aloft.
PWATs of 2-2.5" and instability between 500-1000 J/Kg MUCAPE could
churn out rain rates between 1-1.5"/hr Saturday morning into
afternoon. Ensemble exceedance probabilities of 2 inches are=20
between 5-15% along the far southeastern Louisiana to Florida=20
panhandle corridor, which supports the marginal risk area in=20
place.=20

...Southeast Coast...

Inverted troughing continues along the Florida/Southeast Coast
through the latter part of this weekend. Anomalous moisture (2-3=20
stndv) will continue interacting with the surface boundary to=20
generate scattered to isolated thunderstorms across the=20
Florida/Georgia coast. Rainfall totals of 1-3" are likely along=20
the Florida/Georgia/South Carolina coast on Saturday. The latest=20
guidance has trended away from tropical moisture making its way=20
inland, therefore a marginal risk was maintained for much of the=20
Southeast Coast.


Kebede


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!8lou75ZfJWo2XtaYp7O5H36FbT1XQ0rdJuOpCqww5bLk= W6qQh2J7MWsvbtYwrLDOhkHS6lLKjThVbWuFloWTkAaU93w$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!8lou75ZfJWo2XtaYp7O5H36FbT1XQ0rdJuOpCqww5bLk= W6qQh2J7MWsvbtYwrLDOhkHS6lLKjThVbWuFloWTugsQsDQ$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!8lou75ZfJWo2XtaYp7O5H36FbT1XQ0rdJuOpCqww5bLk= W6qQh2J7MWsvbtYwrLDOhkHS6lLKjThVbWuFloWT2N5mr7I$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 041538
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1138 AM EDT Sat Oct 4 2025

Day 1
Valid 16Z Sat Oct 4 2025 - 12Z Sun Oct 5 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE EASTERN GREAT BASIN ALONG WITH THE CENTRAL GULF COAST AND
COASTAL GEORGIA DOWN THROUGH THE FLORIDA EAST COAST...

...Eastern Great Basin...

16Z Update: Upon examination of current radar trends in northern
Utah, it appears the mesoscale convective vortex associated with
the mid-level upper low is still producing widespread moderate to
heavy rainfall from the greater Salt Lake City area to near the
Idaho border. Movement of the vortex is slowly towards the NNE, and
recent CAM guidance suggests this will persist through about 18-20Z
before lifting out of the region and weakening. Therefore, the
existing Marginal Risk area will remain valid for now.

Previous discussion...

An amplifying upper-level trough advancing through the Great Basin
will be driving multiple waves of low pressure northeastward along
a frontal zone draped across the Intermountain Region. The latest
forecast guidance supports a strengthening mid to upper-level
closed low circulation pivoting across northern UT early this
morning before ejecting through western WY this afternoon. Strong
dynamics/DPVA will ride up across northern UT along with far
southeast ID and western WY which will be interacting with the
front and the pooling of modest instability (MLCAPE ~500 J/kg)
along it for an axis of locally heavy showers and thunderstorms.
Much of this threat will be this morning (notably in the 12Z to 18Z
time frame) as the height falls pivot across the region. The 00Z
HREF guidance suggests some organized convection that will be
capable of producing 1 to 2+ inches of rain which may include some
brief cell-training concerns for areas near and west of the
Wasatch front including around the Great Salt Lake. Can't rule out
there being at least some isolated runoff/flash flooding concerns
from these stronger clusters of convection that evolve this
morning. Therefore, a Marginal Risk of excessive rainfall has been
introduced, but this again is mainly for early in the period today.

...Central Gulf Coast...

A low to mid-level vort center/disturbance over the northern Gulf
is forecast to slowly advance westward today which will help to=20
bring stronger low-level southeast flow and moisture into southeast
LA and coastal MS. Sufficient low-level forcing associated with=20
the vort energy coupled with at least modest instability with=20
MLCAPE values of 1000 to 1500 J/kg will support there being at=20
least scattered bands of convection that will develop and advance=20
inland across the central Gulf Coast. Some of the 00Z HREF guidance
and recent RRFS solutions suggest some linearly oriented=20
convective bands potentially setting up that would support some=20
locally enhanced rainfall totals. Given the improving PW=20
environment with values of 1.75 to 2+ inches, and a convergent=20
southeast low-level jet of 30+ kts, some of the rainfall rates may=20
reach or exceed 2 inches/hour. The potential banded nature of the=20
activity may support some localized rainfall totals going into=20
early Sunday morning of 2 to 4+ inches. These rains will pose at=20
least an isolated threat for flash flooding, and especially if any=20
of these heavier rains were to make into the New Orleans=20
metropolitan area.=20

The existing Marginal Risk of excessive rainfall has been=20
maintained for this period for the central Gulf Coast, but trimmed=20
back to southeastern Louisiana south of Lake Pontchartrain where=20
the highest rainfall coverage is likely to reside.

...Coastal Georgia and the Florida East Coast...

Low-level easterly flow will persist today and tonight across the
FL East Coast given the placement of a well-established area of
surface high pressure farther north over the Mid-Atlantic states.
However, the surface ridging is forecast by the models to shift
offshore by later today which will allow for some veering and
strengthening of the Atlantic fetch a bit farther north up into
coastal areas of eastern GA. The latest hires model guidance
suggests a stronger axis of low-level moisture convergence along
with pooling of instability into coastal areas of eastern GA and
near the SC border. Some locally focused bands of relatively shallow/warm-topped convection may attempt impact the coastal
areas here, with some guidance suggesting locally a couple inches
of rain being possible. Farther south, the FL East Coast should
continue to see scattered to broken areas of showers and
potentially a few thunderstorms. However, the activity should
remain disorganized given a lack of deeper layer forcing and only
modest low-level convergence along the coast. Any runoff concerns=20
from heavy rainfall will tend to be highly isolated and primarily=20
focused over the more urbanized areas. No changes were necessary to
the ongoing Marginal Risk area for this region.

Hamrick/Orrison


Day 2
Valid 12Z Sun Oct 05 2025 - 12Z Mon Oct 06 2025

...THERE IS MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE CENTRAL GULF COAST, THE SOUTHEAST COAST, AND THE CENTRAL
PLAINS...

...Central Gulf Coast...

A weak disturbance in the western Gulf will likely continue to focus
enhanced convergence and convection along portions of the central
Gulf Coast into Sunday. Heaviest rainfall totals may tend to stay
just offshore where the better instability will reside...although
coastal convergence and instability into the immediate coastline
should allow for some heavier cells to make it onshore. Even our
deterministic QPF, which is a multi model blend, brings two day
rainfall totals as high as 3-5" over far southeast LA and right
around 3" along coastal MS and AL. Given the convective nature of
rainfall and PWs over 2" would expect totals to locally exceed these
amounts, and isolated instances of flash flooding are possible. The
00z REFS probabilities of 8" is over 90% across coastal MS/AL. This
is seemingly an under dispersed ensemble in this case, but
interesting nonetheless, and possibly indicative of a lower
probability worst case scenario. Either way, will need to continue
to monitor trends, as can not rule out the need for a Slight risk
along portions of the immediate coast.

...Southeast Coast...

The model QPF signal continues to trend down across the Southeast
coast, although onshore easterly flow, coastal convergence and PWs
around 2" will support localized instances of heavy rainfall.
Overall the flash flood risk appears pretty low, but an isolated
threat can not be ruled out.

...Central Plains...

Convection will likely expand in coverage Sunday evening across
portions of northeast KS, southeast NE and southwest IA. A stalling
frontal boundary will allow for persistent moisture convergence in
the lower levels coupled with a divergence signature aloft. Thus it
seems probable that rainfall will persist through much of the night,
not moving all that much over that time. Whether we see any flash
flood risk evolve will likely come down to the degree of instability
present. It seems likely that we will initially have enough
instability for deeper convection and 1"+ an hour rainfall. However
most indications are that this instability axis will be rather
narrow and under 1000 j/kg. Thus would expect that instability to
get eroded fairly quickly, resulting in decreasing rainfall rates
overnight. Nonetheless, our latest deterministic QPF has 1-2" of
rain, with 2-3" if you include the rain that continues into Monday.
When accounting for convection resulting in locally heavier amounts,
and the possibility that instability ends up greater than forecast
(which a couple models show) then a low end flash flood risk can not
be ruled out.

Chenard


Day 3
Valid 12Z Mon Oct 06 2025 - 12Z Tue Oct 07 2025

...THERE IS MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS EASTERN
FLORIDA AND THE CENTRAL PLAINS...

...Eastern FL...

The 00z ECMWF, AIFS and GEFS mean all suggest an increase in
convective coverage over eastern FL on Monday compared to Sunday.
The approach of a subtle mid level wave may help increase low level
easterly moisture transport while also providing a bit more in the
way of upper divergence. Isolated urban flash flooding should thus
remain a threat into Monday, although would anticipate the risk to
stay quite localized. There has been a clear model trend away from
bringing heavier rainfall into SC/GA and thus the northern extent of
the Marginal risk was cut back.

...Central Plains...

Some convection will likely be ongoing Monday morning across
portions of northeast KS, southeast NE, southwest IA and northwest
MO. The stalled front will remain in the area through the day likely
helping focus additional convection that should only slowly drift
southward. Instability should increase Monday along this front,
however this will coincide with a decrease in moisture transport and convergence along the front. Thus not really anticipating anything
more than a very localized flash flood risk. The threat is likely a
lower end Marginal risk, but given the slow front and two day
rainfall totals of 2", to perhaps as high as 3-4", across this
corridor, localized flooding can not be ruled out. We will maintain
the inherited Marginal risk, but shrink to to better coincide with
the axis of highest two day rainfall totals.

Chenard


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!4axyas_ABHT28kL5L2Qt_blvD6pLxYxGQRpIpXeCQHlk= I5mP0nIqG9NOrCcc0rXSkgtwPt-HX-5XHO8pItnQ5KVnKUI$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!4axyas_ABHT28kL5L2Qt_blvD6pLxYxGQRpIpXeCQHlk= I5mP0nIqG9NOrCcc0rXSkgtwPt-HX-5XHO8pItnQA094Ens$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!4axyas_ABHT28kL5L2Qt_blvD6pLxYxGQRpIpXeCQHlk= I5mP0nIqG9NOrCcc0rXSkgtwPt-HX-5XHO8pItnQukx3IW4$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 050050
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
850 PM EDT Sat Oct 4 2025

Day 1
Valid 01Z Sun Oct 05 2025 - 12Z Sun Oct 05 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF=20
THE CENTRAL GULF COAST...

Maintained a small Marginal Risk area covering far southeastern
Louisiana and coastal Mississippi. While much of the heavier activity associated with a slow-moving wave has remained offshore into this
evening, guidance indicates that veering flow will be enough to=20
nudge both deeper moisture (PWs over 2 inches) and greater=20
instability further north, raising the threat for increasing rain=20
rates and accumulations along the coastal regions overnight. Recent
runs of the HRRR have been consistent in showing a signal for=20
localized heavy amounts moving onshore, while both the 18Z HREF and
the 12Z RRFS indicate that isolated totals over 3 inches are=20
possible.

Pereira

Day 2
Valid 12Z Sun Oct 05 2025 - 12Z Mon Oct 06 2025

...THERE IS MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE CENTRAL GULF COAST, THE SOUTHEAST COAST, AND THE CENTRAL
PLAINS...

20Z Update: There has been an additional lighter trend in the
guidance for the coastal portions of Georgia, and the majority of
heavier showers in onshore flow is expected to be across eastern
Florida, so the new Marginal Risk area is trimmed back to
Jacksonville. For the Midwest, the Marginal Risk is extended a
little more to the northeast to include northeastern Iowa where a
relatively narrow band of higher QPF ahead of a slow moving cold
front is likely to be, with the potential for some convective
training that may result in a few instances of flooding where cells
persist the longest. All seems on track with the Marginal Risk area
for the central Gulf Coast. /Hamrick

Previous discussion...

...Central Gulf Coast...

A weak disturbance in the western Gulf will likely continue to focus
enhanced convergence and convection along portions of the central
Gulf Coast into Sunday. Heaviest rainfall totals may tend to stay
just offshore where the better instability will reside...although
coastal convergence and instability into the immediate coastline
should allow for some heavier cells to make it onshore. Even our
deterministic QPF, which is a multi model blend, brings two day
rainfall totals as high as 3-5" over far southeast LA and right
around 3" along coastal MS and AL. Given the convective nature of
rainfall and PWs over 2" would expect totals to locally exceed these
amounts, and isolated instances of flash flooding are possible. The
00z REFS probabilities of 8" is over 90% across coastal MS/AL. This
is seemingly an under dispersed ensemble in this case, but
interesting nonetheless, and possibly indicative of a lower
probability worst case scenario. Either way, will need to continue
to monitor trends, as can not rule out the need for a Slight risk
along portions of the immediate coast.

...Southeast Coast...

The model QPF signal continues to trend down across the Southeast
coast, although onshore easterly flow, coastal convergence and PWs
around 2" will support localized instances of heavy rainfall.
Overall the flash flood risk appears pretty low, but an isolated
threat can not be ruled out.

...Central Plains...

Convection will likely expand in coverage Sunday evening across
portions of northeast KS, southeast NE and southwest IA. A stalling
frontal boundary will allow for persistent moisture convergence in
the lower levels coupled with a divergence signature aloft. Thus it
seems probable that rainfall will persist through much of the night,
not moving all that much over that time. Whether we see any flash
flood risk evolve will likely come down to the degree of instability
present. It seems likely that we will initially have enough
instability for deeper convection and 1"+ an hour rainfall. However
most indications are that this instability axis will be rather
narrow and under 1000 j/kg. Thus would expect that instability to
get eroded fairly quickly, resulting in decreasing rainfall rates
overnight. Nonetheless, our latest deterministic QPF has 1-2" of
rain, with 2-3" if you include the rain that continues into Monday.
When accounting for convection resulting in locally heavier amounts,
and the possibility that instability ends up greater than forecast
(which a couple models show) then a low end flash flood risk can not
be ruled out.

Chenard


Day 3
Valid 12Z Mon Oct 06 2025 - 12Z Tue Oct 07 2025

...THERE IS MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS EASTERN
FLORIDA AND THE CENTRAL PLAINS...

...Eastern Florida...

The 00z ECMWF, AIFS and GEFS mean all suggest an increase in
convective coverage over eastern FL on Monday compared to Sunday.
The approach of a subtle mid level wave may help increase low level
easterly moisture transport while also providing a bit more in the
way of upper divergence. Isolated urban flash flooding should thus
remain a threat into Monday, although would anticipate the risk to
stay quite localized.

...Central Plains...

Some convection will likely be ongoing Monday morning across
portions of northeast KS, southeast NE, southwest IA and northwest
MO. The stalled front will remain in the area through the day likely
helping focus additional convection that should only slowly drift
southward. Instability should increase Monday along this front,
however this will coincide with a decrease in moisture transport and convergence along the front. Thus not really anticipating anything
more than a very localized flash flood risk. The threat is likely a
lower end Marginal risk, but given the slow front and two day
rainfall totals of 2", to perhaps as high as 3-4", across this
corridor, localized flooding is possible. The existing Marginal
Risk has been maintained with this update.

...Ohio Valley...

A Marginal Risk area has been introduced from eastern Arkansas to
southern Indiana. Moist return flow around a surface high off the
East Coast, in tandem with a frontal boundary slowly approaching
from the northwest, will result in a corridor of warm air advection
with scattered to numerous showers and thunderstorms developing.
Dewpoints rising into the upper 60s to lower 70s, in combination
with increasing mixed layer CAPE, will provide enough instability
for higher rainfall rates that may result in some instances of
flooding, mainly in the 18Z Monday-6Z Tuesday time period.

Hamrick/Chenard


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!8oPy0UYpPNvPJ6vH3Hqklmg11eP5HNEh2yww0dSR3rib= aKxxd5GgHvC9WnKRkBmmj0uySXYUwtRElPD8doK8lsGzmbE$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!8oPy0UYpPNvPJ6vH3Hqklmg11eP5HNEh2yww0dSR3rib= aKxxd5GgHvC9WnKRkBmmj0uySXYUwtRElPD8doK8Tw0inpw$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!8oPy0UYpPNvPJ6vH3Hqklmg11eP5HNEh2yww0dSR3rib= aKxxd5GgHvC9WnKRkBmmj0uySXYUwtRElPD8doK83O3et8I$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 050819
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
419 AM EDT Sun Oct 5 2025

Day 1
Valid 12Z Sun Oct 05 2025 - 12Z Mon Oct 06 2025

...THERE IS MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE CENTRAL PLAINS AND MIDWEST ALONG WITH THE CENTRAL GULF COAST=20
AND EASTERN FLORIDA...

...Central Plains/Midwest...

In the wake of an upper-level trough and surface low transiting
portions of the northern Plains, a cold front will be gradually
settling southeastward today and tonight across the central Plains
and Midwest. Showers and thunderstorms are expected to develop
along the front by this evening across areas of central and
northern KS up through southeast NE and through central IA. MLCAPE
values as high as 1000 to 1500 J/kg are forecast to pool along the
boundary along with a seasonably moist airmass characterized by PWs
of 1.25 to 1.5+ inches. Moisture transport along the front will be
aided by a southwest low-level jet of 30 to 40+ kts going through=20
00Z this evening which coupled with the instability should help=20
drive some heavier rainfall rates capable of reaching 1 to 1.5=20
inches/hour. Going through Sunday night, the convection is expected
to linger as at least modest right-entrance region upper jet=20
dynamics overhead continue to interact with the front. Some post-=20
frontal shower and thunderstorm activity is expected as a pool of=20
elevated instability and frontogenesis lingers over the region. A=20
consensus of the 00Z HREF guidance supports some spotty 2 to 3+=20
inch rainfall totals in a narrow axis along the front. Antecedent=20
conditions are quite dry, but with some localized cell-training=20
concerns and heavier rainfall totals, there may be some isolated=20
and mainly urbanized runoff concerns. A Marginal Risk of excessive=20
rainfall will be maintained across the region.

...Central Gulf Coast...

An elongated low to mid-level low center/trough over the northwest
Gulf of America is expected to focus a corridor of stronger
convergence and moisture transport across the central Gulf Coast
region, with potential for multiple bands of very heavy showers and thunderstorms to evolve. The convection will be embedded within a=20
deep tropical environment characterized by PWs of 2 to 2.25=20
inches. This coupled with MLCAPE values of locally near 1500 J/kg=20
will help favor high rainfall rates that may easily reach 2 to 3=20
inches/hour with the stronger and more organized convective bands.=20
The 00Z HREF guidance generally supports the heaviest rainfall=20
totals remaining confined to the immediate Gulf Coast, however some
localized bands of convection that will be capable of cell-
training may be able to spread a bit farther inland including areas
of south-central to southeast LA through far southern MS and far=20
southern AL. Some urbanized Gulf Coast locations including New=20
Orleans and Mobile may be impacted going through Sunday night by=20
bands of heavy showers and thunderstorms. The latest REFS/RRFS=20
guidance is more aggressive with the rainfall potential, but a=20
HREF-led consensus of guidance would suggest some 2 to 4 inch=20
rainfall totals with spotty 5+ inch amounts not out of the question
where any cell-training occurs. The Marginal Risk area will be=20
maintained for the time being, with isolated areas of flash=20
flooding possible, and especially for the aforementioned urban=20
corridors. However, should the guidance trend any wetter, a Slight=20
Risk upgrade may be warranted for portions of the central Gulf=20
Coast.

...Eastern FL...

Moist and locally convergent low-level easterly Atlantic flow will
continue along the FL East Coast today. There are some locally
heavier rainfall signals showing up along the Space and Treasure
Coasts and stretching inland somewhat as the potential once again
for some broken bands of locally heavy showers and thunderstorms
sets up. Where any cell-training occurs within these bands, some
spotty rainfall totals of 2 to 4+ inches will be possible. This=20
may result in there being a highly localized concern for some
runoff problems. A Marginal Risk of excessive rainfall will be
maintained at this time.

Orrison


Day 2
Valid 12Z Mon Oct 06 2025 - 12Z Tue Oct 07 2025

...THERE IS MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF=20
EASTERN ARKANSAS INTO THE OHIO VALLEY AND OVER EASTERN FLORIDA...

...TN and OH Valley...

A Marginal risk was maintained from portions of eastern AR=20
northeastward into southern IN. 850mb vorticity fields indicate the=20
tropical disturbance in the Gulf is likely to lift northward on=20
Monday brining increased PWs and the potential for areas of slow=20
moving convection. Scattered convection is expected during the day,=20
although the better focus for high rainfall amounts should come=20
Monday night as the approaching cold front from the west helps=20
increase convergence. The environment appears to favor efficient=20
warm rain processes...with the presence of the low level vorticity=20
from the Gulf and PWs around or above 2" (over the climatological=20
90th percentile). Only weak instability is forecast, which could end=20
up being a limiting factor for flash flooding. However, given the=20
expected efficient warm rain, there should still be enough=20
instability to get hourly rainfall rates into the 1-2" range in=20
spots. The latest WPC deterministic QPF is 1-2" across the area,=20
although several models indicate locally higher amounts. Given the=20 environment in place amounts locally getting into the 2-4" range=20
seems reasonable within the Marginal risk area.=20

Expect at least localized instances of flash flooding to be=20
possible, especially by Monday night. There is a bit of uncertainty=20 regarding the exact rainfall axis, with the new 00z ECMWF shifting=20
farther east into more of TN and KY. The eastern extent of the=20
Marginal risk was extended in this direction to account for this=20 potential...although the broader model consensus still favors a=20
slightly farther west axis, in line with the WPC QPF.

...Eastern FL...

Easterly low level flow will continue to support scattered=20
convection over eastern FL Monday into Monday night. Model guidance=20 continues to depict a modest uptick in rainfall coverage and=20
magnitudes on Monday compared to Sunday. Localized urban flash flood=20
impacts will remain possible.

...Central Plains...

We opted to remove the Marginal risk that stretched from northeast=20
KS into southern IA with this update. A localized flash flood risk=20
still exists on day 1, but by Monday the areas hit hardest on day 1=20
will be well north of the surface front. Thus most of the=20
instability will be gone, and rainfall rates should be much lower.=20
Thus the additional rainfall is not expected to be enough to result=20
in flash flooding. A bit more instability may reside over MO, but=20
this is south of the forecast rainfall axis on Sunday, and thus the=20
rainfall Monday is not expected to be enough to overcome the drier=20 antecedent conditions here.

Chenard


Day 3
Valid 12Z Tue Oct 07 2025 - 12Z Wed Oct 08 2025

...THERE IS MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF=20
THE TENNESSEE AND OHIO VALLEY, OVER SOUTHEAST FLORIDA, AND PORTIONS=20
OF NEW MEXICO...

...TN and OH Valley...

A Marginal risk was maintained from TN northward into portions of OH=20
and southwest PA. Increasing moisture ahead of an approaching cold=20
front will likely lead to greater convective coverage and areas of=20
heavy rainfall. The forcing and moisture will be enhanced by the=20
same low level vorticity feature that was upstream on Monday and=20
over the Gulf on Sunday. With PWs forecast over the climatological=20
90th percentile do expect some warm rain processes, which should=20
help overcome marginal instability and help produce heavy rainfall=20
rates. Also note a well defined upper divergence signature centered=20
over this region within the right entrance region of an upper jet.=20
Thus the ingredients are there for widespread rainfall and at least=20
some pockets of heavy rates.=20

The main question for flash flood potential will be the duration of=20
these higher rates. Overall the front looks pretty progressive,=20
which should limit this duration. However, guidance does indicate=20
that some training could occur for a period Tuesday before the front=20
clears through, with the favored axis somewhere in the vicinity of=20
central to eastern KY. While differing on location, most 00z=20
deterministic models indicates a swath of 2-3" of rainfall, which=20
seems reasonable given the environment in place. In fact would not=20
be surprised if totals locally exceed 3". Overall this seems like a=20
solid Marginal risk with localized areas of flash flooding probable.=20
Can not rule out an embedded Slight risk upgrade on future updates=20
pending model trends.

The northern extent of the Marginal risk was cut out of the=20
Northeast with this update. Instability really drops off with=20
northern extent which will impact rainfall rate potential. These=20
lower rates combined with the drought conditions suggest flash=20
flooding is unlikely. We would probably need higher rates to overcome=20
the dry soil conditions, and this seems unlikely given the currently=20 forecast instability. So it is looking more like a beneficial=20
rainfall, with most areas around 0.75" but locally as high as 1.25"=20
or so.

...Southeast FL...

Expecting another day of scattered convection within the easterly low=20
level flow Tuesday. Compared to previous days the threat should=20
mostly be focused over southeast FL by this time, and a localized=20
urban flash flood risk is possible.

...NM...

A Marginal risk was maintained for portions of central and eastern=20
NM on Tuesday. Easterly low level post frontal flow will help=20
locally enhance convergence and upslope and scattered convection is=20
likely to develop. With PWs around 1" and CAPE only forecast between=20 500-1000 j/kg this is likely a lower end threat. Nonetheless,=20
locally heavier convection with high rates could result in isolated=20
flash flooding, particularly over any more sensitive burn scars or=20
basins.

Chenard


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!8GvKwZltCeq5dZISEPQgVenkSTOu5CSAgX3QmqpZvOjM= pDD1Jx0V9vb00eCMAPZazLpfiAgE73imvZzj3Iq1QkH4KYQ$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!8GvKwZltCeq5dZISEPQgVenkSTOu5CSAgX3QmqpZvOjM= pDD1Jx0V9vb00eCMAPZazLpfiAgE73imvZzj3Iq1qbyCR_Q$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!8GvKwZltCeq5dZISEPQgVenkSTOu5CSAgX3QmqpZvOjM= pDD1Jx0V9vb00eCMAPZazLpfiAgE73imvZzj3Iq1hRWOTDE$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 051538
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1138 AM EDT Sun Oct 5 2025

Day 1
Valid 16Z Sun Oct 05 2025 - 12Z Mon Oct 06 2025

...THERE IS MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE CENTRAL PLAINS AND MIDWEST ALONG WITH THE CENTRAL GULF COAST
AND EASTERN FLORIDA...

...16Z Outlook Update...
The ongoing ERO is on track with only minimal changes needed to
current risk areas. Impressive QPF/totals are beginning to show on
high-res models along a focused axis from north-central KS into
west-central IA. However, dry antecedent conditions and lack of
urban flash flood potential/hydrophobic ground surfaces suggests=20
that any flash flood potential should remain isolated. Isolated 4-6
inch rainfall totals are possible especially along the KS/NE=20
border region and points between just north of Salina, KS to west
of Des Moines, IA.

Localized/marginal flash flood potential should exist for a
couple more hours near the Savannah, GA vicinity this morning,
although the temporal window for deep convection (and 2-3 inch/hr
rain rates) is relatively brief and should close early this
afternoon. Excessive runoff is possible, but coverage should=20
remain below 5% there.

Lastly, isolated flash flood potential exists from southeastern
Louisiana eastward across the north-central Gulf Coast today
through early evening. A weak low is drifting northward toward
southern Louisiana and loosely organized, banded convection should
develop toward the Marginal Risk area in an abundantly moist
environment (2+ inch PW values). Storms should be slow-moving
enough for local rain rates of 2 inches/hr to occur on an
isolated/sporadic basis. This scenario should result in at least
isolated instances of excessive runoff through the afternoon and
evening.

See the previous discussion below for more information.

Cook

...Previous Discussion...

...Central Plains/Midwest...

In the wake of an upper-level trough and surface low transiting
portions of the northern Plains, a cold front will be gradually
settling southeastward today and tonight across the central Plains
and Midwest. Showers and thunderstorms are expected to develop
along the front by this evening across areas of central and
northern KS up through southeast NE and through central IA. MLCAPE
values as high as 1000 to 1500 J/kg are forecast to pool along the
boundary along with a seasonably moist airmass characterized by PWs
of 1.25 to 1.5+ inches. Moisture transport along the front will be
aided by a southwest low-level jet of 30 to 40+ kts going through
00Z this evening which coupled with the instability should help
drive some heavier rainfall rates capable of reaching 1 to 1.5
inches/hour. Going through Sunday night, the convection is expected
to linger as at least modest right-entrance region upper jet
dynamics overhead continue to interact with the front. Some post-
frontal shower and thunderstorm activity is expected as a pool of
elevated instability and frontogenesis lingers over the region. A
consensus of the 00Z HREF guidance supports some spotty 2 to 3+
inch rainfall totals in a narrow axis along the front. Antecedent
conditions are quite dry, but with some localized cell-training
concerns and heavier rainfall totals, there may be some isolated
and mainly urbanized runoff concerns. A Marginal Risk of excessive
rainfall will be maintained across the region.

...Central Gulf Coast...

An elongated low to mid-level low center/trough over the northwest
Gulf of America is expected to focus a corridor of stronger
convergence and moisture transport across the central Gulf Coast
region, with potential for multiple bands of very heavy showers and thunderstorms to evolve. The convection will be embedded within a
deep tropical environment characterized by PWs of 2 to 2.25
inches. This coupled with MLCAPE values of locally near 1500 J/kg
will help favor high rainfall rates that may easily reach 2 to 3
inches/hour with the stronger and more organized convective bands.
The 00Z HREF guidance generally supports the heaviest rainfall
totals remaining confined to the immediate Gulf Coast, however some
localized bands of convection that will be capable of cell-
training may be able to spread a bit farther inland including areas
of south-central to southeast LA through far southern MS and far
southern AL. Some urbanized Gulf Coast locations including New
Orleans and Mobile may be impacted going through Sunday night by
bands of heavy showers and thunderstorms. The latest REFS/RRFS
guidance is more aggressive with the rainfall potential, but a
HREF-led consensus of guidance would suggest some 2 to 4 inch
rainfall totals with spotty 5+ inch amounts not out of the question
where any cell-training occurs. The Marginal Risk area will be
maintained for the time being, with isolated areas of flash
flooding possible, and especially for the aforementioned urban
corridors. However, should the guidance trend any wetter, a Slight
Risk upgrade may be warranted for portions of the central Gulf
Coast.

...Eastern FL...

Moist and locally convergent low-level easterly Atlantic flow will
continue along the FL East Coast today. There are some locally
heavier rainfall signals showing up along the Space and Treasure
Coasts and stretching inland somewhat as the potential once again
for some broken bands of locally heavy showers and thunderstorms
sets up. Where any cell-training occurs within these bands, some
spotty rainfall totals of 2 to 4+ inches will be possible. This
may result in there being a highly localized concern for some
runoff problems. A Marginal Risk of excessive rainfall will be
maintained at this time.

Orrison


Day 2
Valid 12Z Mon Oct 06 2025 - 12Z Tue Oct 07 2025

...THERE IS MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
EASTERN ARKANSAS INTO THE OHIO VALLEY AND OVER EASTERN FLORIDA...

...TN and OH Valley...

A Marginal risk was maintained from portions of eastern AR
northeastward into southern IN. 850mb vorticity fields indicate the
tropical disturbance in the Gulf is likely to lift northward on
Monday brining increased PWs and the potential for areas of slow
moving convection. Scattered convection is expected during the day,
although the better focus for high rainfall amounts should come
Monday night as the approaching cold front from the west helps
increase convergence. The environment appears to favor efficient
warm rain processes...with the presence of the low level vorticity
from the Gulf and PWs around or above 2" (over the climatological
90th percentile). Only weak instability is forecast, which could end
up being a limiting factor for flash flooding. However, given the
expected efficient warm rain, there should still be enough
instability to get hourly rainfall rates into the 1-2" range in
spots. The latest WPC deterministic QPF is 1-2" across the area,
although several models indicate locally higher amounts. Given the
environment in place amounts locally getting into the 2-4" range
seems reasonable within the Marginal risk area.

Expect at least localized instances of flash flooding to be
possible, especially by Monday night. There is a bit of uncertainty
regarding the exact rainfall axis, with the new 00z ECMWF shifting
farther east into more of TN and KY. The eastern extent of the
Marginal risk was extended in this direction to account for this potential...although the broader model consensus still favors a
slightly farther west axis, in line with the WPC QPF.

...Eastern FL...

Easterly low level flow will continue to support scattered
convection over eastern FL Monday into Monday night. Model guidance
continues to depict a modest uptick in rainfall coverage and
magnitudes on Monday compared to Sunday. Localized urban flash flood
impacts will remain possible.

...Central Plains...

We opted to remove the Marginal risk that stretched from northeast
KS into southern IA with this update. A localized flash flood risk
still exists on day 1, but by Monday the areas hit hardest on day 1
will be well north of the surface front. Thus most of the
instability will be gone, and rainfall rates should be much lower.
Thus the additional rainfall is not expected to be enough to result
in flash flooding. A bit more instability may reside over MO, but
this is south of the forecast rainfall axis on Sunday, and thus the
rainfall Monday is not expected to be enough to overcome the drier
antecedent conditions here.

Chenard


Day 3
Valid 12Z Tue Oct 07 2025 - 12Z Wed Oct 08 2025

...THERE IS MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE TENNESSEE AND OHIO VALLEY, OVER SOUTHEAST FLORIDA, AND PORTIONS
OF NEW MEXICO...

...TN and OH Valley...

A Marginal risk was maintained from TN northward into portions of OH
and southwest PA. Increasing moisture ahead of an approaching cold
front will likely lead to greater convective coverage and areas of
heavy rainfall. The forcing and moisture will be enhanced by the
same low level vorticity feature that was upstream on Monday and
over the Gulf on Sunday. With PWs forecast over the climatological
90th percentile do expect some warm rain processes, which should
help overcome marginal instability and help produce heavy rainfall
rates. Also note a well defined upper divergence signature centered
over this region within the right entrance region of an upper jet.
Thus the ingredients are there for widespread rainfall and at least
some pockets of heavy rates.

The main question for flash flood potential will be the duration of
these higher rates. Overall the front looks pretty progressive,
which should limit this duration. However, guidance does indicate
that some training could occur for a period Tuesday before the front
clears through, with the favored axis somewhere in the vicinity of
central to eastern KY. While differing on location, most 00z
deterministic models indicates a swath of 2-3" of rainfall, which
seems reasonable given the environment in place. In fact would not
be surprised if totals locally exceed 3". Overall this seems like a
solid Marginal risk with localized areas of flash flooding probable.
Can not rule out an embedded Slight risk upgrade on future updates
pending model trends.

The northern extent of the Marginal risk was cut out of the
Northeast with this update. Instability really drops off with
northern extent which will impact rainfall rate potential. These
lower rates combined with the drought conditions suggest flash
flooding is unlikely. We would probably need higher rates to overcome
the dry soil conditions, and this seems unlikely given the currently
forecast instability. So it is looking more like a beneficial
rainfall, with most areas around 0.75" but locally as high as 1.25"
or so.

...Southeast FL...

Expecting another day of scattered convection within the easterly low
level flow Tuesday. Compared to previous days the threat should
mostly be focused over southeast FL by this time, and a localized
urban flash flood risk is possible.

...NM...

A Marginal risk was maintained for portions of central and eastern
NM on Tuesday. Easterly low level post frontal flow will help
locally enhance convergence and upslope and scattered convection is
likely to develop. With PWs around 1" and CAPE only forecast between
500-1000 j/kg this is likely a lower end threat. Nonetheless,
locally heavier convection with high rates could result in isolated
flash flooding, particularly over any more sensitive burn scars or
basins.

Chenard


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!_9lhZdipesCCQRyq3tylsHawmDLtgay6msNrhgkNYJmJ= UR9jI3e1mKUCyaqdl1S9ulbqa5b15iZ7RHduvw996Wb7xqk$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!_9lhZdipesCCQRyq3tylsHawmDLtgay6msNrhgkNYJmJ= UR9jI3e1mKUCyaqdl1S9ulbqa5b15iZ7RHduvw99f3jfreQ$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!_9lhZdipesCCQRyq3tylsHawmDLtgay6msNrhgkNYJmJ= UR9jI3e1mKUCyaqdl1S9ulbqa5b15iZ7RHduvw99eo3L4ss$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 051933
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
333 PM EDT Sun Oct 5 2025

Day 1
Valid 16Z Sun Oct 05 2025 - 12Z Mon Oct 06 2025

...THERE IS MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE CENTRAL PLAINS AND MIDWEST ALONG WITH THE CENTRAL GULF COAST
AND EASTERN FLORIDA...

...16Z Outlook Update...
The ongoing ERO is on track with only minimal changes needed to
current risk areas. Impressive QPF/totals are beginning to show on
high-res models along a focused axis from north-central KS into
west-central IA. However, dry antecedent conditions and lack of
urban flash flood potential/hydrophobic ground surfaces suggests
that any flash flood potential should remain isolated. Isolated 4-6
inch rainfall totals are possible especially along the KS/NE
border region and points between just north of Salina, KS to west
of Des Moines, IA.

Localized/marginal flash flood potential should exist for a
couple more hours near the Savannah, GA vicinity this morning,
although the temporal window for deep convection (and 2-3 inch/hr
rain rates) is relatively brief and should close early this
afternoon. Excessive runoff is possible, but coverage should
remain below 5% there.

Lastly, isolated flash flood potential exists from southeastern
Louisiana eastward across the north-central Gulf Coast today
through early evening. A weak low is drifting northward toward
southern Louisiana and loosely organized, banded convection should
develop toward the Marginal Risk area in an abundantly moist
environment (2+ inch PW values). Storms should be slow-moving
enough for local rain rates of 2 inches/hr to occur on an
isolated/sporadic basis. This scenario should result in at least
isolated instances of excessive runoff through the afternoon and
evening.

See the previous discussion below for more information.

Cook

...Previous Discussion...

...Central Plains/Midwest...

In the wake of an upper-level trough and surface low transiting
portions of the northern Plains, a cold front will be gradually
settling southeastward today and tonight across the central Plains
and Midwest. Showers and thunderstorms are expected to develop
along the front by this evening across areas of central and
northern KS up through southeast NE and through central IA. MLCAPE
values as high as 1000 to 1500 J/kg are forecast to pool along the
boundary along with a seasonably moist airmass characterized by PWs
of 1.25 to 1.5+ inches. Moisture transport along the front will be
aided by a southwest low-level jet of 30 to 40+ kts going through
00Z this evening which coupled with the instability should help
drive some heavier rainfall rates capable of reaching 1 to 1.5
inches/hour. Going through Sunday night, the convection is expected
to linger as at least modest right-entrance region upper jet
dynamics overhead continue to interact with the front. Some post-
frontal shower and thunderstorm activity is expected as a pool of
elevated instability and frontogenesis lingers over the region. A
consensus of the 00Z HREF guidance supports some spotty 2 to 3+
inch rainfall totals in a narrow axis along the front. Antecedent
conditions are quite dry, but with some localized cell-training
concerns and heavier rainfall totals, there may be some isolated
and mainly urbanized runoff concerns. A Marginal Risk of excessive
rainfall will be maintained across the region.

...Central Gulf Coast...

An elongated low to mid-level low center/trough over the northwest
Gulf of America is expected to focus a corridor of stronger
convergence and moisture transport across the central Gulf Coast
region, with potential for multiple bands of very heavy showers and thunderstorms to evolve. The convection will be embedded within a
deep tropical environment characterized by PWs of 2 to 2.25
inches. This coupled with MLCAPE values of locally near 1500 J/kg
will help favor high rainfall rates that may easily reach 2 to 3
inches/hour with the stronger and more organized convective bands.
The 00Z HREF guidance generally supports the heaviest rainfall
totals remaining confined to the immediate Gulf Coast, however some
localized bands of convection that will be capable of cell-
training may be able to spread a bit farther inland including areas
of south-central to southeast LA through far southern MS and far
southern AL. Some urbanized Gulf Coast locations including New
Orleans and Mobile may be impacted going through Sunday night by
bands of heavy showers and thunderstorms. The latest REFS/RRFS
guidance is more aggressive with the rainfall potential, but a
HREF-led consensus of guidance would suggest some 2 to 4 inch
rainfall totals with spotty 5+ inch amounts not out of the question
where any cell-training occurs. The Marginal Risk area will be
maintained for the time being, with isolated areas of flash
flooding possible, and especially for the aforementioned urban
corridors. However, should the guidance trend any wetter, a Slight
Risk upgrade may be warranted for portions of the central Gulf
Coast.

...Eastern FL...

Moist and locally convergent low-level easterly Atlantic flow will
continue along the FL East Coast today. There are some locally
heavier rainfall signals showing up along the Space and Treasure
Coasts and stretching inland somewhat as the potential once again
for some broken bands of locally heavy showers and thunderstorms
sets up. Where any cell-training occurs within these bands, some
spotty rainfall totals of 2 to 4+ inches will be possible. This
may result in there being a highly localized concern for some
runoff problems. A Marginal Risk of excessive rainfall will be
maintained at this time.

Orrison


Day 2
Valid 12Z Mon Oct 06 2025 - 12Z Tue Oct 07 2025

...THERE IS SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF=20
THE MID-SOUTH AND WESTERN OHIO VALLEY...

...TN and OH Valley...

...1900 UTC Update...

Based on the latest (12Z) CAM guidance, including the full HREF
probabilistic suite, per collaboration with the WFOs have hoisted a
Slight Risk area across far northeast AR, southeast MO, western
TN-KY, southern IL, and southwest IN (essentially the confluence=20
of the OH and MS River basins). As noted from the previous=20
discussion (below), warm-rain processes will be fairly optimal=20
given the abundant low-mid layer moisture associated with the=20
subtropical shortwave (TPWs approaching 2.00", or 2 standard=20
deviations above the norm, along with WBZ levels aoa 13.5kft).=20
Therefore despite not much deep-layer instability (MUCAPEs 500-1000
J/Kg), rainfall rates will nevertheless be highly efficient. HREF=20 neighborhood probabilities of 24hr rainfall amounts exceeding 3 and
5 inches are highest within this Slight Risk area (60-70% and=20
40-50% respectively).=20

Hurley

...Previous Discussion...

850mb vorticity fields indicate the tropical disturbance in the=20
Gulf is likely to lift northward on Monday brining increased PWs=20
and the potential for areas of slow moving convection. Scattered=20
convection is expected during the day, although the better focus=20
for high rainfall amounts should come Monday night as the=20
approaching cold front from the west helps increase convergence.=20
The environment appears to favor efficient warm rain=20
processes...with the presence of the low level vorticity from the=20
Gulf and PWs around or above 2" (over the climatological 90th=20
percentile). Only weak instability is forecast, which could end up=20
being a limiting factor for flash flooding. However, given the=20
expected efficient warm rain, there should still be enough=20
instability to get hourly rainfall rates into the 1-2" range in=20
spots. The latest WPC deterministic QPF is 1-2" across the area,=20
although several models indicate locally higher amounts. Given the=20 environment in place amounts locally getting into the 2-4" range=20
seems reasonable within the Marginal risk area.

Expect at least localized instances of flash flooding to be
possible, especially by Monday night. There is a bit of uncertainty
regarding the exact rainfall axis, with the new 00z ECMWF shifting
farther east into more of TN and KY. The eastern extent of the
Marginal risk was extended in this direction to account for this potential...although the broader model consensus still favors a
slightly farther west axis, in line with the WPC QPF.

...Eastern FL...

Easterly low level flow will continue to support scattered
convection over eastern FL Monday into Monday night. Model guidance
continues to depict a modest uptick in rainfall coverage and
magnitudes on Monday compared to Sunday. Localized urban flash flood
impacts will remain possible.

...Central Plains...

We opted to remove the Marginal risk that stretched from northeast
KS into southern IA with this update. A localized flash flood risk
still exists on day 1, but by Monday the areas hit hardest on day 1
will be well north of the surface front. Thus most of the
instability will be gone, and rainfall rates should be much lower.
Thus the additional rainfall is not expected to be enough to result
in flash flooding. A bit more instability may reside over MO, but
this is south of the forecast rainfall axis on Sunday, and thus the
rainfall Monday is not expected to be enough to overcome the drier
antecedent conditions here.

Chenard


Day 3
Valid 12Z Tue Oct 07 2025 - 12Z Wed Oct 08 2025

...THERE IS SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS NORTHERN
TENNESSEE AND MUCH OF KENTUCKY INTO WESTERN PORTIONS OF WEST
VIRGINIA...

...TN and OH Valley...

...1900 UTC Update...

Only minor tweaks were made to the Marginal Risk area, however as
with the Day 2 ERO, we've added a low-end Slight Risk area on Day 3
from portions of northern TN and much of KY east-northeast into
western WV. This again follows along with the subtropical wave and
TPW plume that will be absorbed by the longwave (synoptic scale)=20
trough and associated surface front. Just as with Day 2, the deep-=20
layer instability isn't overly robust (MUCAPEs 500-1000 J/Kg tops),
while at the same time the flattening mid-upper trough across the=20
area (increasing deep-layer westerly flow) should allow for more a=20
faster W to E progression of the shortwave and surface front later=20
in the period (late Tue-Tue night). Still, anomalous deep-layer=20
moisture (warm rain processes as WBZ levels remain over 12KFT) will
allow for rather efficient short-term rainfall rates.=20

Hurley

...Previous Discussion...

Increasing moisture ahead of an approaching cold front
will likely lead to greater convective coverage and areas of heavy
rainfall. The forcing and moisture will be enhanced by the same=20
low level vorticity feature that was upstream on Monday and over=20
the Gulf on Sunday. With PWs forecast over the climatological 90th=20 percentile do expect some warm rain processes, which should help=20
overcome marginal instability and help produce heavy rainfall=20
rates. Also note a well defined upper divergence signature centered
over this region within the right entrance region of an upper jet.
Thus the ingredients are there for widespread rainfall and at=20
least some pockets of heavy rates.

The main question for flash flood potential will be the duration of
these higher rates. Overall the front looks pretty progressive,
which should limit this duration. However, guidance does indicate
that some training could occur for a period Tuesday before the front
clears through, with the favored axis somewhere in the vicinity of
central to eastern KY. While differing on location, most 00z
deterministic models indicates a swath of 2-3" of rainfall, which
seems reasonable given the environment in place. In fact would not
be surprised if totals locally exceed 3". Overall this seems like a
solid Marginal risk with localized areas of flash flooding probable.
Can not rule out an embedded Slight risk upgrade on future updates
pending model trends.

The northern extent of the Marginal risk was cut out of the
Northeast with this update. Instability really drops off with
northern extent which will impact rainfall rate potential. These
lower rates combined with the drought conditions suggest flash
flooding is unlikely. We would probably need higher rates to overcome
the dry soil conditions, and this seems unlikely given the currently
forecast instability. So it is looking more like a beneficial
rainfall, with most areas around 0.75" but locally as high as 1.25"
or so.

...Southeast FL...

Expecting another day of scattered convection within the easterly low
level flow Tuesday. Compared to previous days the threat should
mostly be focused over southeast FL by this time, and a localized
urban flash flood risk is possible.

...NM...

A Marginal risk was maintained for portions of central and eastern
NM on Tuesday. Easterly low level post frontal flow will help
locally enhance convergence and upslope and scattered convection is
likely to develop. With PWs around 1" and CAPE only forecast between
500-1000 j/kg this is likely a lower end threat. Nonetheless,
locally heavier convection with high rates could result in isolated
flash flooding, particularly over any more sensitive burn scars or
basins.

Chenard


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!-4jOVPqDRtzQd4mGBuzL64YLpmeMmCOg1791tFPDn_Ar= xddDi9fcanDksSoayd2lLkUNX1k6SCa472Zu3VehwHNTzl4$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!-4jOVPqDRtzQd4mGBuzL64YLpmeMmCOg1791tFPDn_Ar= xddDi9fcanDksSoayd2lLkUNX1k6SCa472Zu3VehZh7iAFA$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!-4jOVPqDRtzQd4mGBuzL64YLpmeMmCOg1791tFPDn_Ar= xddDi9fcanDksSoayd2lLkUNX1k6SCa472Zu3VehmN1VoIc$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

FOUS30 KWBC 060050
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
850 PM EDT Sun Oct 5 2025

Day 1
Valid 01Z Mon Oct 06 2025 - 12Z Mon Oct 06 2025

...THERE IS MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE CENTRAL PLAINS AND MIDWEST ALONG WITH THE CENTRAL GULF COAST
AND EASTERN FLORIDA...

01Z Update...
Latest guidance indicates that at least a localized threat for
additional heavy rainfall will persist tonight within each of the=20
outlook areas, which may lead to isolated runoff concerns.=20
Therefore, each area was maintained, with minor adjustments.=20

The broken line of showers and storms that has developed along the
cold front from western Kansas northeastward into the upper=20
Mississippi Valley shows the greatest potential for scattered heavy
amounts. PWs of 1.25-1.5 inches. along with MUCAPEs above 1000=20
J/kg have been supporting spotty rainfall rates up to ~1 inch/hr=20
from western Kansas though southeastern Nebraska into southwestern=20
Iowa. Recent runs of the HRRR along with the HREF and RRFS indicate
some isolated totals of 2-3 inches are possible along this=20
corridor tonight.

Pereira


Previous Discussion...
...Central Plains/Midwest...

In the wake of an upper-level trough and surface low transiting
portions of the northern Plains, a cold front will be gradually
settling southeastward today and tonight across the central Plains
and Midwest. Showers and thunderstorms are expected to develop
along the front by this evening across areas of central and
northern KS up through southeast NE and through central IA. MLCAPE
values as high as 1000 to 1500 J/kg are forecast to pool along the
boundary along with a seasonably moist airmass characterized by PWs
of 1.25 to 1.5+ inches. Moisture transport along the front will be
aided by a southwest low-level jet of 30 to 40+ kts going through
00Z this evening which coupled with the instability should help
drive some heavier rainfall rates capable of reaching 1 to 1.5
inches/hour. Going through Sunday night, the convection is expected
to linger as at least modest right-entrance region upper jet
dynamics overhead continue to interact with the front. Some post-
frontal shower and thunderstorm activity is expected as a pool of
elevated instability and frontogenesis lingers over the region. A
consensus of the 00Z HREF guidance supports some spotty 2 to 3+
inch rainfall totals in a narrow axis along the front. Antecedent
conditions are quite dry, but with some localized cell-training
concerns and heavier rainfall totals, there may be some isolated
and mainly urbanized runoff concerns. A Marginal Risk of excessive
rainfall will be maintained across the region.

...Central Gulf Coast...

An elongated low to mid-level low center/trough over the northwest
Gulf of America is expected to focus a corridor of stronger
convergence and moisture transport across the central Gulf Coast
region, with potential for multiple bands of very heavy showers and thunderstorms to evolve. The convection will be embedded within a
deep tropical environment characterized by PWs of 2 to 2.25
inches. This coupled with MLCAPE values of locally near 1500 J/kg
will help favor high rainfall rates that may easily reach 2 to 3
inches/hour with the stronger and more organized convective bands.
The 00Z HREF guidance generally supports the heaviest rainfall
totals remaining confined to the immediate Gulf Coast, however some
localized bands of convection that will be capable of cell-
training may be able to spread a bit farther inland including areas
of south-central to southeast LA through far southern MS and far
southern AL. Some urbanized Gulf Coast locations including New
Orleans and Mobile may be impacted going through Sunday night by
bands of heavy showers and thunderstorms. The latest REFS/RRFS
guidance is more aggressive with the rainfall potential, but a
HREF-led consensus of guidance would suggest some 2 to 4 inch
rainfall totals with spotty 5+ inch amounts not out of the question
where any cell-training occurs. The Marginal Risk area will be
maintained for the time being, with isolated areas of flash
flooding possible, and especially for the aforementioned urban
corridors. However, should the guidance trend any wetter, a Slight
Risk upgrade may be warranted for portions of the central Gulf
Coast.

...Eastern FL...

Moist and locally convergent low-level easterly Atlantic flow will
continue along the FL East Coast today. There are some locally
heavier rainfall signals showing up along the Space and Treasure
Coasts and stretching inland somewhat as the potential once again
for some broken bands of locally heavy showers and thunderstorms
sets up. Where any cell-training occurs within these bands, some
spotty rainfall totals of 2 to 4+ inches will be possible. This
may result in there being a highly localized concern for some
runoff problems. A Marginal Risk of excessive rainfall will be
maintained at this time.

Orrison


Day 2
Valid 12Z Mon Oct 06 2025 - 12Z Tue Oct 07 2025

...THERE IS SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE MID-SOUTH AND WESTERN OHIO VALLEY...

...TN and OH Valley...

...1900 UTC Update...

Based on the latest (12Z) CAM guidance, including the full HREF
probabilistic suite, per collaboration with the WFOs have hoisted a
Slight Risk area across far northeast AR, southeast MO, western
TN-KY, southern IL, and southwest IN (essentially the confluence
of the OH and MS River basins). As noted from the previous
discussion (below), warm-rain processes will be fairly optimal
given the abundant low-mid layer moisture associated with the
subtropical shortwave (TPWs approaching 2.00", or 2 standard
deviations above the norm, along with WBZ levels aoa 13.5kft).
Therefore despite not much deep-layer instability (MUCAPEs 500-1000
J/Kg), rainfall rates will nevertheless be highly efficient. HREF
neighborhood probabilities of 24hr rainfall amounts exceeding 3 and
5 inches are highest within this Slight Risk area (60-70% and
40-50% respectively).

Hurley

...Previous Discussion...

850mb vorticity fields indicate the tropical disturbance in the
Gulf is likely to lift northward on Monday brining increased PWs
and the potential for areas of slow moving convection. Scattered
convection is expected during the day, although the better focus
for high rainfall amounts should come Monday night as the
approaching cold front from the west helps increase convergence.
The environment appears to favor efficient warm rain
processes...with the presence of the low level vorticity from the
Gulf and PWs around or above 2" (over the climatological 90th
percentile). Only weak instability is forecast, which could end up
being a limiting factor for flash flooding. However, given the
expected efficient warm rain, there should still be enough
instability to get hourly rainfall rates into the 1-2" range in
spots. The latest WPC deterministic QPF is 1-2" across the area,
although several models indicate locally higher amounts. Given the
environment in place amounts locally getting into the 2-4" range
seems reasonable within the Marginal risk area.

Expect at least localized instances of flash flooding to be
possible, especially by Monday night. There is a bit of uncertainty
regarding the exact rainfall axis, with the new 00z ECMWF shifting
farther east into more of TN and KY. The eastern extent of the
Marginal risk was extended in this direction to account for this potential...although the broader model consensus still favors a
slightly farther west axis, in line with the WPC QPF.

...Eastern FL...

Easterly low level flow will continue to support scattered
convection over eastern FL Monday into Monday night. Model guidance
continues to depict a modest uptick in rainfall coverage and
magnitudes on Monday compared to Sunday. Localized urban flash flood
impacts will remain possible.

...Central Plains...

We opted to remove the Marginal risk that stretched from northeast
KS into southern IA with this update. A localized flash flood risk
still exists on day 1, but by Monday the areas hit hardest on day 1
will be well north of the surface front. Thus most of the
instability will be gone, and rainfall rates should be much lower.
Thus the additional rainfall is not expected to be enough to result
in flash flooding. A bit more instability may reside over MO, but
this is south of the forecast rainfall axis on Sunday, and thus the
rainfall Monday is not expected to be enough to overcome the drier
antecedent conditions here.

Chenard


Day 3
Valid 12Z Tue Oct 07 2025 - 12Z Wed Oct 08 2025

...THERE IS SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS NORTHERN
TENNESSEE AND MUCH OF KENTUCKY INTO WESTERN PORTIONS OF WEST
VIRGINIA...

...TN and OH Valley...

...1900 UTC Update...

Only minor tweaks were made to the Marginal Risk area, however as
with the Day 2 ERO, we've added a low-end Slight Risk area on Day 3
from portions of northern TN and much of KY east-northeast into
western WV. This again follows along with the subtropical wave and
TPW plume that will be absorbed by the longwave (synoptic scale)
trough and associated surface front. Just as with Day 2, the deep-
layer instability isn't overly robust (MUCAPEs 500-1000 J/Kg tops),
while at the same time the flattening mid-upper trough across the
area (increasing deep-layer westerly flow) should allow for more a
faster W to E progression of the shortwave and surface front later
in the period (late Tue-Tue night). Still, anomalous deep-layer
moisture (warm rain processes as WBZ levels remain over 12KFT) will
allow for rather efficient short-term rainfall rates.

Hurley

...Previous Discussion...

Increasing moisture ahead of an approaching cold front
will likely lead to greater convective coverage and areas of heavy
rainfall. The forcing and moisture will be enhanced by the same
low level vorticity feature that was upstream on Monday and over
the Gulf on Sunday. With PWs forecast over the climatological 90th
percentile do expect some warm rain processes, which should help
overcome marginal instability and help produce heavy rainfall
rates. Also note a well defined upper divergence signature centered
over this region within the right entrance region of an upper jet.
Thus the ingredients are there for widespread rainfall and at
least some pockets of heavy rates.

The main question for flash flood potential will be the duration of
these higher rates. Overall the front looks pretty progressive,
which should limit this duration. However, guidance does indicate
that some training could occur for a period Tuesday before the front
clears through, with the favored axis somewhere in the vicinity of
central to eastern KY. While differing on location, most 00z
deterministic models indicates a swath of 2-3" of rainfall, which
seems reasonable given the environment in place. In fact would not
be surprised if totals locally exceed 3". Overall this seems like a
solid Marginal risk with localized areas of flash flooding probable.
Can not rule out an embedded Slight risk upgrade on future updates
pending model trends.

The northern extent of the Marginal risk was cut out of the
Northeast with this update. Instability really drops off with
northern extent which will impact rainfall rate potential. These
lower rates combined with the drought conditions suggest flash
flooding is unlikely. We would probably need higher rates to overcome
the dry soil conditions, and this seems unlikely given the currently
forecast instability. So it is looking more like a beneficial
rainfall, with most areas around 0.75" but locally as high as 1.25"
or so.

...Southeast FL...

Expecting another day of scattered convection within the easterly low
level flow Tuesday. Compared to previous days the threat should
mostly be focused over southeast FL by this time, and a localized
urban flash flood risk is possible.

...NM...

A Marginal risk was maintained for portions of central and eastern
NM on Tuesday. Easterly low level post frontal flow will help
locally enhance convergence and upslope and scattered convection is
likely to develop. With PWs around 1" and CAPE only forecast between
500-1000 j/kg this is likely a lower end threat. Nonetheless,
locally heavier convection with high rates could result in isolated
flash flooding, particularly over any more sensitive burn scars or
basins.

Chenard


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!4rTPxeEY5RSMIzcXvzHW9OgJjW5UEDtyiwHbULsJ2PR1= dN9shQI0O2IUoQ8ZcfqnPNorSPu1iXIq3HXibU01ATRPeT0$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!4rTPxeEY5RSMIzcXvzHW9OgJjW5UEDtyiwHbULsJ2PR1= dN9shQI0O2IUoQ8ZcfqnPNorSPu1iXIq3HXibU011NgFZP4$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!4rTPxeEY5RSMIzcXvzHW9OgJjW5UEDtyiwHbULsJ2PR1= dN9shQI0O2IUoQ8ZcfqnPNorSPu1iXIq3HXibU01Um6lnc8$=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)