ACUS48 KWNS 080856
SWOD48
SPC AC 080854

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0354 AM CDT Wed Apr 08 2026

Valid 111200Z - 161200Z

...DISCUSSION...
...Saturday/Day 4 to Monday/Day 6...
On Saturday, mid-level southwesterly flow will strengthen over the
central U.S., as an upper-level system moves to near the West Coast.
A moist airmass will be in place over the southern and central
Plains, as a low-amplitude shortwave trough moves across the region. Large-scale ascent along with warming surface temperatures will
result in scattered thunderstorm development over much of west Texas
Saturday afternoon. MLCAPE is expected to peak near 1000 J/kg in
some areas, with 0-6 km shear being in the 30 to 40 knot range over
much of the southern High Plains. This should be sufficient for a
severe threat, with large hail and severe wind gusts possible.

From Saturday night into Sunday, strong moisture advection is
forecast over the Great Plains. By Sunday afternoon, moderate
instability is expected to be in place over much of this airmass.
Isolated to scattered severe thunderstorms are expected throughout
much of the moist sector during the afternoon and evening. Some
model forecasts move a 50 to 60 knot mid-level jet through central
and northeast Texas during the afternoon and evening. If this
happens, then a substantial severe threat would be possible from
parts of central and north Texas into Oklahoma. Severe storms,
including supercells with large hail, wind damage and a tornado
threat would be possible in areas that destabilize the most.

On Monday, a moist and unstable airmass is forecast to remain from
the southern Plains extending north-northeastward into the Upper
Midwest. Strong to severe thunderstorm development will be possible
over much of the instability corridor in the afternoon and evening.
The greatest potential for severe storms is forecast from the
southern Plains north-northeastward into the lower Missouri Valley
and upper Mississippi Valley, where the models develop moderate
instability and have 0-6 km shear mostly in the 30 to 40 knot range.
Severe storms with large hail, wind damage and a tornado threat will
be possible.

...Tuesday/Day 7 and Wednesday/Day 8...
The western U.S. trough is finally forecast to approach the southern
Plains on Tuesday, where a moist and unstable airmass should be in
place. Some solutions suggest that a mid-level jet will move into
the southern Plains Tuesday afternoon. This would create strong
deep-layer shear over parts of the moist sector, suggesting that a
substantial severe threat will be possible. Although there is still
spatial uncertainty regarding this scenario, current model forecasts
would support supercells with large hail, severe wind gusts and some
tornadoes.

On Wednesday, a shortwave trough is forecast to move through the
central states, with a southwest-to-northeast corridor of moderate
instability in place by afternoon from northeast Texas into western
Ozarks. This would be favorable for severe storms. However, at this
extended range, considerable uncertainty exists concerning severe
threat magnitude and spacing.

..Broyles.. 04/08/2026

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ACUS48 KWNS 090900
SWOD48
SPC AC 090858

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0358 AM CDT Thu Apr 09 2026

Valid 121200Z - 171200Z

...DISCUSSION...
...Sunday/Day 4 to Tuesday/Day 6...
On Sunday, southwesterly mid-level flow will be in place across much
of the nation. At the surface, a moist airmass will be located from
the southern Plains north-northeastward into the Upper Midwest. Much
of this corridor is forecast to become moderately unstable by
afternoon. The greatest potential for severe storms will likely be
in the southern and central Plains, where some solutions have a
subtle shortwave trough. Moderate deep-layer shear and steep lapse
rates will be favorable for supercells with large hail and severe
wind gusts.

Mid-level flow is forecast to gradually strengthen across the
central U.S. on Monday. In response moisture advection will continue
in the Great Plains. By Monday afternoon, moderate instability
should be in place from north Texas northward into the upper
Mississippi Valley. Isolated to scattered thunderstorms are expected
to develop across this airmass Monday afternoon and evening.
Moderate deep-layer shear and steep lapse rates will again be
favorable for severe storms capable of large hail and severe wind
gusts. A tornado threat may also develop.

On Tuesday, an upper-level trough is forecast to move eastward into
the southern Rockies, as an associated mid-level jet streak ejects northeastward across the southern High Plains. A moderately unstable
airmass will likely be in place by afternoon from the southern
Plains northeastward into mid to upper Mississippi Valley and
southern Great Lakes. Strong deep-layer shear is forecast over the
southern and central Plains, where a substantial severe threat will
be possible. Supercells with large hail, wind damage and tornadoes
are expected Tuesday afternoon and evening. An upgrade will be
possible across parts of the threat area, once confidence increases
on the timing of the ejecting trough.

...Wednesday/Day 7 and Thursday/Day 8...
The upper-level trough is forecast to move eastward across the
central U.S. on Wednesday, as a cold front advances southeastward
through the Great Plains and Upper Midwest. Moderate instability is
forecast to develop ahead of much of the front. Thunderstorms that
form in areas that destabilize sufficiently could have a severe
threat. The severe potential will likely continue into Thursday, as
the front advances southeastward into the mid Mississippi Valley.
However, model spread concerning the position of the front and
timing of the trough increases substantially toward mid week,
suggesting a lot of uncertainty exists at this extended range in the
period.

..Broyles.. 04/09/2026

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ACUS48 KWNS 100830
SWOD48
SPC AC 100828

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0328 AM CDT Fri Apr 10 2026

Valid 131200Z - 181200Z

...DISCUSSION...
...Days 4-6/Mon-Wed -- Central/Southern Plains to the Midwest...

There is quite a bit of uncertainty regarding severe
potential/evolution during the Monday-Wednesday period. An upper
trough will slowly pivot across the West on Monday, and emerge over
the central/southern Rockies by early Wednesday before finally
ejecting across the Plains and toward the Mid/Upper MS Valley on
Wednesday. During this time, broad southwesterly deep-layer flow
will overspread the Plains into the Mid/Upper MS Valley.

On Monday, a surface low will develop over the northern/central
Plains, with a dryline extending southward across KS/OK/TX and a
warm front extending across southern MN/WI. Several lead shortwave
impulses will move across the Plains, though height tendencies will
remain mostly neutral. Nevertheless, cooling aloft will support
steep midlevel lapse rates and increasing boundary layer moisture
(surface dewpoints in the low/mid 60s F) will support moderate to
strong destabilization. During the evening, a southwesterly
low-level jet will increase across the Plains, overspreading the
surface dryline. Vertically veering wind profiles and 30-40 kt
effective shear magnitudes would support supercells capable of all
hazards, though storm coverage remains uncertain.

By Tuesday, the GFS becomes more progressive with the western
trough, ejecting it into the Plains by early Wednesday, whereas the
ECMWF hangs the trough back west and is slower. Nevertheless, a
similar airmass will be in place across the warm sector east of a
dryline across the Plains and to the south of a warm front draped
across the Great Lakes. Isolated convection may develop along the
dryline across the Plains, posing a supercell/all-hazards risk.
Higher storm coverage appears more likely across portions of the
Mid/Upper MS Valley/Great Lakes vicinity closer to a surface low.

On Wednesday, the upper trough should progress from the Plains to
the Great Lakes while weakening some. A surface cold front will
develop southeast across portions of the central U.S. and some
severe risk should persist along/ahead of this boundary. How
convection evolves on Tuesday into Wednesday will impact where the
greatest severe risk will develop, but at least some risk should
exist from portions of the southern Plains to the Mid-MS Valley.

...Days 7-8/Thu-Fri...

Predictability is low heading into the end of the forecast period on
Thursday and Friday as large spread exists among medium range
guidance. However, western U.S. upper troughing may persist,
suggesting some severe thunderstorm potential could persist for
parts of the Plains late in the work week.

..Leitman.. 04/10/2026

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ACUS48 KWNS 110846
SWOD48
SPC AC 110844

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0344 AM CDT Sat Apr 11 2026

Valid 141200Z - 191200Z

...DISCUSSION...
...Day 4/Tue -- Southern Plains to Great Lakes...

A shortwave upper trough embedded within the larger-scale western
U.S. trough will eject across portions of the Plains to the Upper
Midwest on Day 4/Tue. As this occurs, a surface low will deep over
the central Plains and lift northeast across the Upper Midwest/Great
Lakes. Some uncertainty remains regarding the exact evolution of
this system, mainly due to differences in medium range guidance with
respect to surface low placement and timing of the upper shortwave
trough. Nevertheless, a moist and unstable airmass is expected ahead
of the low and to the east of a Plains dryline and south of a Great
Lakes warm front. Thunderstorm development should be more widespread
along these boundaries compared to prior days given stronger
large-scale ascent will overspread the central U.S., and height
falls will result in a more robust low-level jet response. As a
result, an all-hazards severe event is expected from the southern
Plains into portions of the Upper Midwest/Great Lakes vicinity on Tuesday/Tuesday night.

...Day 5/Wed -- Southern Plains to the Midwest...

Medium range guidance varies heading into Wednesday with the
operational GFS much more progressive and lower amplitude than the
operational ECMWF. The AIGFS is much more in-line with the
ECMWF/AIFS, so this period is weighted more toward those solutions.
It appears the upper trough over the southern Rockies will eject
across the Plains to the Mid-MS Valley during this time. A moist and
unstable airmass will reside across the region ahead of dryline
across western OK into central TX and a sagging cold front across
the Lower MO/Mid-MS Valley. Areas of precipitation could be ongoing
at the beginning of the period and does result in some uncertainty
regarding where stronger destabilization will occur. Nevertheless,
an overall favorable thermodynamic/kinematic parameter space will
overlap this corridor and isolated to scattered severe storms appear
likely.

...Days 6-8/Thu-Sat...

Medium range guidance depicts another trough developing across the
West on Day 6/Thu and quickly progressing east through the end of
the period. This could support a continued severe risk across parts
of the southern Plains into the Midwest in the Thursday or Friday
time frame. However, run to run consistency toward the end of the
forecast period has not been very good. Additionally, multiple
rounds of storms across the same areas earlier in the period may
impact later severe potential. Trends will be monitored and
probabilities may be needed in later outlooks.

..Leitman.. 04/11/2026

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ACUS48 KWNS 120841
SWOD48
SPC AC 120839

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0339 AM CDT Sun Apr 12 2026

Valid 151200Z - 201200Z

...DISCUSSION...
...Day 4/Wed - Southern Plains to southern Wisconsin...

An upper trough will be oriented over the central/southern High
Plains Wednesday morning. This feature will shift east to the
Mississippi River by Thursday morning. As this occurs, strong
deep-layer southwesterly flow will overspread a moist and unstable
airmass from TX toward the Great Lakes. Some convection may be
ongoing Wednesday morning, resulting in some uncertainty regarding
airmass recovery and convective evolution during the
afternoon/evening. However, persistent southerly low-level flow
ahead of a dryline and continued warm advection should support areas
of airmass recovery. A mix of supercells and linear segments will be
possible, posing an all-hazards severe risk.

...Day 5/Thu...

Severe potential should be lower on Thursday as the upper trough and
weakens at it shifts east across the Ohio Valley. Widespread showers
and thunderstorms will be possible from parts of the Great
Lakes/Ohio Valley into the TN Valley, with modest instability and
limited heating tempering severe potential.

...Day 6/Fri - Southern Plains to Upper Midwest...

Medium range guidance has been fairly consistent the past several
forecast cycles in bringing a large-scale upper eastward from the
Rockies into the Plains Friday/Friday night. This should result in
surface cyclogenesis across portions of the Upper Midwest with a
trailing cold front extending into the southern Plains. Ahead of the
front, a seasonally moist/unstable airmass will be in place beneath strengthening southwesterly deep-layer flow. This should support a
severe risk ahead of the front.

...Days 7-8/Sat-Sun...

The upper trough will continue east over the eastern U.S. on
Saturday and Sunday. Stronger ascent will shift northeast into
Canada. Deep-layer flow parallel to the surface front and a
narrowing warm sector should limit severe potential.

..Leitman.. 04/12/2026

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ACUS48 KWNS 130846
SWOD48
SPC AC 130844

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0344 AM CDT Mon Apr 13 2026

Valid 161200Z - 211200Z

...DISCUSSION...
...Day 4/Thu - Mid-South vicinity...

An upper shortwave trough will develop northeast from eastern OK/TX
to the central/southern Appalachians on Thursday. Convection is
likely to be ongoing from the Mid-MS/Lower OH Valley to the ArkLaTex
region Thursday morning. This will likely temper downstream
destabilization (and overall severe risk), but a few strong storms
are possible across the Mid-South vicinity.

...Day 5/Fri - Southern Plains to Iowa...

Medium range guidance has been consistently showing an upper trough
over the western U.S. developing eastward toward the High Plains
Friday/Friday night. As this occurs, increasing deep-layer
southwesterly flow will overspread a seasonally moist and unstable
airmass. A lee low will deepen over the central/southern High
Plains, with a dryline extending across western OK/TX during the
afternoon. By evening and into the overnight hours, a cold front
will spread southeast across the central/southern Plains and Lower
MO Valley. This pattern will support a risk of severe storms across
the warm sector from OK to IA.

...Days 6-8/Sat-Mon...

Some severe risk may persist into Saturday as a surface low deepens
over the Great Lakes and the cold front from the Day 5/Friday period
continues to sweep east across the Midwest to the Lower MS Valley,
becoming oriented across the Appalachians by Sunday morning. Severe
potential may depend on how convection on Friday evolves and impacts
the downstream airmass heading into Saturday morning, resulting in
low predictability at this time. Strong surface high pressure will
build across the Plains in the wake of the cold front, and Gulf
moisture will become cut-off as the front pushes well south into the
Gulf Basin. This should bring a reprieve from severe thunderstorm
potential Sunday into Monday as surface high pressure envelops much
of the CONUS east of the Rockies by the end of the period.

..Leitman.. 04/13/2026

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ACUS48 KWNS 140833
SWOD48
SPC AC 140831

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0331 AM CDT Tue Apr 14 2026

Valid 171200Z - 221200Z

...DISCUSSION...
...Day 4/Friday - Southern Plains to Upper Midwest...

A strong upper trough oriented from Montana to the Southwest will
eject eastward to the Plains on Friday/Friday night. Southwesterly
mid/upper flow will intensify ahead of this feature, with 40-60 kt
850-700 mb flow forecast by late afternoon into the nighttime hours.
A somewhat complex surface pattern is forecast, with a lee low
deepening over the central/southern High Plains to western OK, and a
second surface low near the Mid-Missouri Valley developing northeast
into Ontario. A surface dryline will extend from the High Plains low
to near the western OK/TX panhandle border into central TX by
midday. Meanwhile, a cold front will be oriented from eastern MN
into central KS at midday.

Ahead of these surface features, a broad warm sector characterized
by mid/upper 60s F dewpoints will be in place as temperatures warm
into the 80s F. A plume of steep midlevel lapse rates will
overspread the region, resulting in moderate to strong
destabilization. Forecast soundings indicated impressive wind
profiles supporting supercells. Initial supercell storms capable of
all hazards (including very large hail and strong tornadoes) are
expected. During the evening, convection may grow upscale into a
squall line as storms near the Mississippi River, with an
accompanying increase in damaging wind potential.

...Day 5/Saturday - Ohio Valley/Great Lakes vicinity...

A severe risk will likely continue into Saturday as the upper trough
continues to strengthen and shift east from the Plains to the Great Lakes/Midwest. Strong deep-layer flow parallel to an
eastward-advancing cold front will overspread a moist and at least
weakly unstable downstream airmass through evening. This will favor
a line of convection with damaging wind potential.

...Days 6-8/Sunday-Tuesday...

The surface cold front will continue east on Sunday, moving offshore
the Atlantic and Gulf coasts during the afternoon. Severe potential
appears limited by weak instability and mainly anafrontal
precipitation across the Southeast to Eastern U.S. on Sunday.
Surface high pressure and a dearth of boundary layer moisture in the
wake of the cold front will preclude thunderstorm activity on
Monday. By the end of the period, medium range guidance depicts
another upper trough moving into the western U.S. and Gulf return
flow will advect moisture back into the southern Plains. However,
severe thunderstorm potential appears low at this time.

..Leitman.. 04/14/2026

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ACUS48 KWNS 140848
SWOD48
SPC AC 140846

Day 4-8 Convective Outlook CORR 1
NWS Storm Prediction Center Norman OK
0346 AM CDT Tue Apr 14 2026

Valid 171200Z - 221200Z

CORRECTED FOR DAY 5 GRAPHIC LABEL

...DISCUSSION...
...Day 4/Friday - Southern Plains to Upper Midwest...

A strong upper trough oriented from Montana to the Southwest will
eject eastward to the Plains on Friday/Friday night. Southwesterly
mid/upper flow will intensify ahead of this feature, with 40-60 kt
850-700 mb flow forecast by late afternoon into the nighttime hours.
A somewhat complex surface pattern is forecast, with a lee low
deepening over the central/southern High Plains to western OK, and a
second surface low near the Mid-Missouri Valley developing northeast
into Ontario. A surface dryline will extend from the High Plains low
to near the western OK/TX panhandle border into central TX by
midday. Meanwhile, a cold front will be oriented from eastern MN
into central KS at midday.

Ahead of these surface features, a broad warm sector characterized
by mid/upper 60s F dewpoints will be in place as temperatures warm
into the 80s F. A plume of steep midlevel lapse rates will
overspread the region, resulting in moderate to strong
destabilization. Forecast soundings indicated impressive wind
profiles supporting supercells. Initial supercell storms capable of
all hazards (including very large hail and strong tornadoes) are
expected. During the evening, convection may grow upscale into a
squall line as storms near the Mississippi River, with an
accompanying increase in damaging wind potential.

...Day 5/Saturday - Ohio Valley/Great Lakes vicinity...

A severe risk will likely continue into Saturday as the upper trough
continues to strengthen and shift east from the Plains to the Great Lakes/Midwest. Strong deep-layer flow parallel to an
eastward-advancing cold front will overspread a moist and at least
weakly unstable downstream airmass through evening. This will favor
a line of convection with damaging wind potential.

...Days 6-8/Sunday-Tuesday...

The surface cold front will continue east on Sunday, moving offshore
the Atlantic and Gulf coasts during the afternoon. Severe potential
appears limited by weak instability and mainly anafrontal
precipitation across the Southeast to Eastern U.S. on Sunday.
Surface high pressure and a dearth of boundary layer moisture in the
wake of the cold front will preclude thunderstorm activity on
Monday. By the end of the period, medium range guidance depicts
another upper trough moving into the western U.S. and Gulf return
flow will advect moisture back into the southern Plains. However,
severe thunderstorm potential appears low at this time.

..Leitman.. 04/14/2026

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ACUS48 KWNS 150755
SWOD48
SPC AC 150753

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0253 AM CDT Wed Apr 15 2026

Valid 181200Z - 231200Z

...DISCUSSION...
...Day 4/Sat - Ohio Valley...

An upper trough will overspread the Great Lakes and Midwest on
Saturday. At the surface, a cold front will sweep east across the
region during the day. Destabilization will likely be limited by
downstream cloud cover within a strong low-level warm advection
regime ahead of the front. Additionally, convection will likely be
ongoing in the vicinity of the front from Lower MI into IN/IL.
Nevertheless, strong mid/upper flow (40-60 kt in the 850-700 mb
layer) will support strong to severe convection even amid weak
instability. As such, a damaging wind gust risk will accompany
linear convection moving across the region during the day into
evening.

...Days 5-6/Sun-Mon...

Strong high pressure in the wake of the cold front from the Day 4
period will overspread much of the CONUS east of the Rockies early
next week. A dry/stable airmass will preclude thunderstorm
potential.

...Days 7-8/Tue-Wed...

An upper trough is forecast to develop across the western U.S. Tuesday/Wednesday. This will result in lee trough development across
the High Plains, and strengthening south/southeasterly low-level
flow will transport Gulf moisture northward across the southern
Plains. Medium range guidance varies on whether or not this western
trough will eject into the Plains during this time, or if upper
ridging will be maintained. If the trough ejects, severe potential
could develop across portions of the southern/central Plains
Tuesday/Wednesday, though predictability is too low at this time to
introduce severe probabilities.

..Leitman.. 04/15/2026

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ACUS48 KWNS 160840
SWOD48
SPC AC 160838

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0338 AM CDT Thu Apr 16 2026

Valid 191200Z - 241200Z

...DISCUSSION...
Severe thunderstorm potential will be low through at least Day
6/Tuesday. In the wake of a cold front moving offshore the Atlantic
coast and into the Gulf, strong surface high pressure will build
east of the Rockies and persist across parts of the South and East
through Day 6/Tuesday. As a result, a dry and stable boundary layer
will preclude severe thunderstorm potential.

By the middle of the week, and upper trough is forecast to
overspread the western U.S. As this occurs, lee surface troughing
will allow for increasing southerly winds over the Plains, and Gulf
moisture will begin to return northward Days 7-8/Wed-Thu. It remains
uncertain if the upper trough will begin to eject eastward toward
the Plains at the end of the period. If this occurs, some severe
potential may develop across the Plains, though predictability is
low.

..Leitman.. 04/16/2026

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ACUS48 KWNS 170743
SWOD48
SPC AC 170741

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0241 AM CDT Fri Apr 17 2026

Valid 201200Z - 251200Z

...DISCUSSION...
A dry, continental airmass will persist across most of the CONUS for
the first part of next week. Severe weather chances will start to
increase by the middle of the week and into the later part of the
week. Forecast guidance consistently shows mid 60s F dewpoints
across the Plains and into the Midwest. However, aloft the pattern
remains quite uncertain. The ECMWF and the GEFS and EPS all show a
developing large-scale trough centered across the western CONUS with
multiple shortwave troughs which could result in severe weather
Day6/Wed to Day 8/Fri. However, the 00Z GFS and the EC-AIFS show a
consolidated mid-level trough which could result in a much more
substantial severe weather event across the central/southern Plains.
At this time, uncertainty is too high for specific risk areas, but
Day6/Wed to Day 8/Fri will likely feature multiple days of severe
weather across portions of the central/southern Plains.

..Bentley.. 04/17/2026

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ACUS48 KWNS 180742
SWOD48
SPC AC 180740

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0240 AM CDT Sat Apr 18 2026

Valid 211200Z - 261200Z

...DISCUSSION...
Initially dry conditions will keep the severe weather threat low on
D4/Tuesday. As a mid-level trough traverses the Rockies on Monday,
lee troughing will strengthen on D5/Wednesday. This will bring
substantial moisture return across the Plains. Given the early stage
moisture return, more than an isolated severe weather threat appears
unlikely on D5.

A more substantial severe weather threat is anticipated on Day
6/Thursday. The evolution of the mid-level trough still remains
unclear, but an overall pattern featuring broad troughing across the southern/central Plains, moderate to strong instability, and a sharp
dryline, could support at least isolated supercells Thursday
afternoon/evening. Have added a 15% area from western/central
Oklahoma into southern/eastern Kansas where the severe weather
threat seems likely regardless of how exactly the mid-level pattern
evolves.

The uncertainties discussed for Day 6 become greater on Day 7 and
beyond. Persistent troughing across the Plains and considerable
instability suggest that severe weather is likely on Friday (and
likely into the weekend). However, the progression of the mid-level
trough and the associated surface features need to become more clear
before a 15% area can be defined for these days.

..Bentley.. 04/18/2026

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ACUS48 KWNS 190902
SWOD48
SPC AC 190900

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0400 AM CDT Sun Apr 19 2026

Valid 221200Z - 271200Z

...DISCUSSION...
A western trough will take hold in the days preceding this
convective period. Ahead of this trough moisture will return
northward through the central Plains, with 50F dewpoints reaching
perhaps as far north as the Canadian border during Wednesday/Day-4.
This return flow setup and western trough will set the stage for
multiple days of severe weather potential.

On Wednesday/Day-4, a lobe of vorticity will eject northeast out of
the western longwave trough across the central and northern Plains.
As this occurs, surface cyclogenesis should take place across the
far northern Plains. To the south of this surface low, a dryline
should sharpen across western Nebraska and Kansas. At the same time,
vertical shear should strengthen as the shortwave moves northeast
across the region. The kinematic profiles will support supercells
initiating along the dryline. However, concerns remain about the
quality of the moisture to the east of the dryline and subsequently
as to the number of potential thunderstorms that may develop. This
uncertainty precluded the introduction of unconditional 15%
probabilities at this time.

On Thursday/Day-5, the shortwave trough/midlevel low will deepen as
it slowly moves north-northeast during the day. This will help
maintain a strong surface cyclone across the northern Plains, with
strong southerly winds advecting Gulf moisture northward to the east
of the north-south oriented frontal boundary. Showers and
thunderstorms will be possible along and east of the aforementioned
frontal boundary across a large portion of the central US. Strong
vertical wind shear across this frontal boundary will promote severe
potential from Oklahoma northward to perhaps as far north as
Minnesota. The northern extent of the severe potential will be
delimited by the degree of moisture return, and have expanded the
unconditional 15% probability area northward into Iowa to account
for the increasing confidence in severe thunderstorm potential.

Overnight Thursday/Day-5, a surface cold front, augmented by
convective outflow, should push east across the northern and central
Plains and south-southeast across the southern Plains. Another round
of severe thunderstorms will be possible on Friday/Day-6 across
portions of northeast Texas/northern Louisiana and much of Arkansas
as diurnal heating of a moist airmass results in MUCAPE values
between 1000-2000 J/kg beneath modest vertical shear associated
persistent southwest midlevel flow.

The severe potential will likely persist into Saturday/Day-7 and
Sunday/Day-8 across portions of the southern Plains and northern
Gulf Coast states. Here, persistent western troughing will maintain
an increasingly moist airmass along and south of the aforementioned
frontal boundary. The location of this frontal boundary will likely
be significantly impacted by the repeated rounds of thunderstorms in
the prior days. Model guidance is in general agreement that at least
modest westerly/southwesterly flow will persist across the southern
Plains, with episodic perturbations traversing this flow field
downstream of the broader large-scale western trough. However,
significant differences remain with respect to the timing, strength,
and location of any of these perturbations to attempt to highlight unconditional severe probabilities.

..Marsh.. 04/19/2026

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ACUS48 KWNS 200900
SWOD48
SPC AC 200858

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0358 AM CDT Mon Apr 20 2026

Valid 231200Z - 281200Z

...DISCUSSION...
In the days preceding this forecast period, a long-wave trough will
develop across the western US. This feature will persist across the
western and central US through the forecast period supporting a
multi-day severe weather threat across portions of the central US.

On Thursday/Day-4, a lobe of vorticity will rotate around the closed
midlevel low across the northern Rockies. This will reinforce a
surface cyclone as it moves north into Canada. As this low moves
north, a combined dryline/cold front will move east into an
increasingly moist environment across the central Plains. The
airmass ahead of the front should destabilize during the day
Thursday, with MUCAPE values over 1000 J/kg possible into portions
of Minnesota.

Thunderstorms should develop across portions of northeast Kansas
into Iowa during the late afternoon as height falls overspread the
surface front. These storms should quickly build southward along the
front into portions of Oklahoma and southern Kansas. Kinematic
fields initially should support supercells, but midlevel flow will
increasingly become parallel to the front suggesting that storms
will grow upscale into one or more linear segments.

The surface front, augmented by convective outflows, will continue
to push south and east into the Southern Plains and the greater
ArkLaTex region overnight Thursday into Friday/Day-5 before stalling
out. Forecast soundings along and ahead of the frontal boundary
indicate an unstable, uncapped environment with vertical shear
between 30-40 knots should support additional severe thunderstorms
Friday afternoon into the evening/overnight across portions of
eastern Oklahoma and Arkansas.

By Saturday/Day-6, the larger-scale flow across the southern Plains
will begin to respond to a low-latitude trough moving into southern
California by once again becoming increasingly southwesterly.
Embedded perturbations within this southwest flow ahead of the main
trough will support an ongoing severe threat across the southern
Plains. However, the location of various surface boundaries
(dryline, outflow, frontal) will be predicated on the evolution of
prior days of convection and the timing of the aforementioned
perturbations in the midlevel flow. Thus, while pattern recognition
suggests severe weather will be possible on Days 6,7, and 8,
certainty as to the location of greatest severe potential on any
given day remains too low to highlight with unconditional
probabilities at this time.

..Marsh.. 04/20/2026

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ACUS48 KWNS 210901
SWOD48
SPC AC 210859

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CDT Tue Apr 21 2026

Valid 241200Z - 291200Z

...DISCUSSION...
... An active severe weather pattern is expected through much of the
forecast period ...

Broadly cyclonic midlevel flow will persist through much of the
forecast period to the south of a closed upper low over
south-central Canada. This will place much of the Southern Plains in
westerly or southwesterly mid- and upper-level flow each day. At the
same time low-level pattern will support southerly flow from the
surface up through 850 mb across the same region. The result will be
an increasingly moist airmass to the east of a north-south dryline
across western Oklahoma and Kansas, and to the south of a remnant
west-to-east frontal boundary.

Diurnal heating of this moist airmass will result in afternoon
MUCAPE values around 2000-3000 J/kg Friday and Saturday beneath
30-40 knots of vertical shear. Model guidance continues to show
several perturbations within the midlevel flow traversing the
Southern Plains on Friday into Sunday morning. The result will be
multiple rounds of severe thunderstorms. The exact location and
dimensions of these daily severe threats will likely be augmented by
the prior days' convection, but the overall pattern supports near
daily severe potential across much of the Southern Plains.

On Sunday (Day 6) a stronger, yet compact, midlevel wave is forecast
to move northeast across Oklahoma. This wave is forecast to induce
cyclogenesis across western Oklahoma, which should act to sharpen a
dryline. To the east of the dryline, strong southerly winds will
support surface dewpoints increasing into the upper 60Fs to perhaps
low 70Fs. Diurnal heating of this airmass will result in MUCAPE
values nearing 4000 J/kg across central Oklahoma. Deep-layer shear
approaching 50 knots will overspread the region during the afternoon
as the main wave approaches. Although global models are struggling
to initiate convection along the dryline, pattern recognition would
support a significant severe weather threat Sunday evening. The lack
of model convective initiation results in enough uncertainty to
preclude the introduction of 30% unconditional severe probabilities.
All severe hazards will be possible on Sunday.

The severe threat will continue into Monday/Day-7 as the midlevel
low and surface cyclone translate east into the lower Mississippi
Valley. The severe threat may continue into Tuesday/Day-8 across
portions of the Southeast US, although numerous days of preceding
convection should use up the steep lapse rate reservoir to the west
resulting in too much uncertainty to introduce unconditional severe probabilities at this time.

..Marsh.. 04/21/2026

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ACUS48 KWNS 220902
SWOD48
SPC AC 220900

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0400 AM CDT Wed Apr 22 2026

Valid 251200Z - 301200Z

...DISCUSSION...
An active severe weather pattern will continue through early next
week.

On Saturday/Day-4, model guidance continues to show thunderstorms
developing during the late afternoon and early evening hours along a
lifting warm front across the Southern Plains. Along and south of
this boundary, the environment will be strongly unstable with MUCAPE
values between 2000-3000 J/kg as a low-level jet continually advects
mid 60Fs dewpoints north across the boundary. Effective layer shear
around 40 knots would support an initial supercell threat that
should grow upscale into bowing segments overnight. A 30% area is
introduced across southwest Kansas into east-central Oklahoma for
the expectation is for strong bowing segments to move east-southeast
overnight into a strong low-level jet. These storms will be capable
of producing strong winds, large hail, and QLCS tornadoes.

On Sunday/Day-5, ongoing convection across southeast Kansas and
western Missouri at the start of the period may pose a continued
risk of hail and damaging winds, and this convection may persist
into mid morning. To the west, continued moist low-level advection
will allow for surface dewpoints to rise into the upper 60Fs to low
70Fs across central Oklahoma to the east of a sharp dryline. At the
same time, a low-amplitude shortwave should approach the Southern
Plains during the late afternoon and evening hours, with a
mid-990-millibar surface low developing across northwest Oklahoma
along the dryline. The result of this setup will be a volatile
atmosphere where MLCAPE values around 4000 J/kg exist within a
strongly shear environment (vertical shear nearly 50 knots). Should thunderstorms initiate, a high-end severe weather threat could
materialize during the late afternoon and evening hours across
central and eastern Oklahoma and southern Kansas. However, global
models continue to struggle to develop convection within this
environment despite model guidance having modest upward vertical
velocities overspreading the dryline. Pattern recognition suggests
the need for a 30% severe area for this potential despite the lack
of a QPF signal in the global models, and have opted to add one with
this forecast. The location of this 30% will likely need to be
refined in subsequent outlooks.

The severe threat should continue into Monday/Day-6 across portions
of the Lower Mississippi Valley. Strong storms should develop along
and ahead of an eastward moving cold front. MUCAPE of 2000-3000 J/kg
and 40-knots of deep-layer shear will support supercell
thunderstorms capable of all severe hazards. The location, number,
and intensity of these supercells will likely be modulated by the
events of Sunday. Specifically, if widespread convection does not
occur Sunday across the Southern Plains, a more robust reservoir of CAPE/lapse-rates will be available to thunderstorms across the Lower Mississippi Valley on Monday and a higher-end severe potential may
develop. This will be monitored in subsequent forecasts.

By Tuesday/Day-7 into Wednesday/Day-8, uncertainty in the severe
potential across the southeast increases too much to have confidence
in identifying specific locations. Although, as the mesoscale
details become cleared in the preceding days, areas may need to be
added in subsequent forecasts.

..Marsh.. 04/22/2026

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ACUS48 KWNS 230905
SWOD48
SPC AC 230904

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0404 AM CDT Thu Apr 23 2026

Valid 261200Z - 011200Z

...DISCUSSION...
A multi-day severe weather event remains on track for Sunday/Day-4
evening through Monday/Day-5, with additional severe storms possible
during the rest of the forecast period.

A vigorous, yet compact, negatively tilted midlevel wave is forecast
to move across the Southwest and eject into the Plains Sunday
evening into Monday. As this wave ejects into the central US, strong
surface cyclogenesis is expected over the Central Plains on Sunday
evening. The flow around this low will help draw very rich boundary
layer moisture northward to the east of a sharpening dryline. The
atmosphere on Sunday across the Southern and Central Plains should
remain capped for much of the day, allowing extreme instability
(SBCAPE/MUCAPE values in excess of 4000 J/kg) to develop. As modest
height falls overspread the dryline during the late afternoon and
evening hours, the expectation is that at least a few storms will be
able to break through the cap. While 20260423/00Z global guidance is
still struggling to produce widespread precipitation along and east
of the dryline, the control members are now at least producing light
QPF along the dryline which would tend to support the idea that
isolated convection will be possible.

The environment to the east of the dryline will be very unstable and increasingly sheared as enhanced midlevel flow overspreads the warm
sector. Additionally, as the surface low deepens during the evening
hours, low-level winds will respond by rapidly increasing to greater
than 50 knots. The result will be the potential for any thunderstorm
that develops and sustains itself to become strong supercells
capable of producing all severe hazards, including significant
severe.

As the main wave continues to lift northeast on Monday, the surface
low should rapidly move from the Central Plains into the Upper
Mississippi Valley. As this occurs, a surface warm front will
rapidly lift northward on the nose of an intense low-level jet. This
low-level jet will likely result in widespread precipitation to the
north of the front, which will have impacts on the northern extent
of Monday afternoon's severe potential.

By Monday afternoon, additional thunderstorms are expected to
develop along and east of an advancing dryline/cold front in an
increasingly unstable atmosphere. Diurnal heating of a boundary
layer with low-to-mid-60Fs dewpoints should result in SBCAPE/MUCAPE
values between 2000-3000 J/kg. Additionally, vertical shear will
remain more than sufficient for supercells. All severe hazards will
remain possible with this convection, with the greatest
concentration of severe storms likely across the Mid-Mississippi
Valley where a 30% area was introduced.

Monday evening into the overnight hours will see a continued
potential for severe storms as the surface front pushes east into
the western portions of the Ohio Valley. Additionally, severe storms
will likely continue across the southwest portion of the front,
which will slowly begin to stall in a southwest-to-northeast or
west-to-east configuration across Arkansas into Kentucky.

Additional severe storms will be possible Tuesday/Day-6 through
Thursday/Day-8 across the Southern and Central Plains into the
Lower-to-Middle Mississippi Valley as cyclonic midlevel flow
persists atop a moist boundary layer with a frontal boundary
somewhere across the area. However, given the uncertainties in how
the convective evolution of Sunday and Monday will impact the
location of relevant surface features and the general uncertainty
associated with identifying the timing of midlevel perturbations
embedded within the broader scale cyclonic midlevel flow,
unconditional 15% severe probabilities will be deferred to
subsequent outlooks.

..Marsh.. 04/23/2026

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ACUS48 KWNS 240903
SWOD48
SPC AC 240901

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0401 AM CDT Fri Apr 24 2026

Valid 271200Z - 021200Z

...DISCUSSION...
Latest medium-range model output suggests that a significant short
wave perturbation emerging from the Southwest will pivot northeast
of the middle/lower Missouri Valley, into the upper Great Lakes
region, Monday through Monday night. It appears that the warm
sector of an associated sub-1000 mb surface cyclone will become
characterized by at least moderately large CAPE, ahead of the
dryline/cold front overspreading much of the middle Mississippi
Valley during the afternoon into evening. In the presence of strong
deep-layer shear, organized severe thunderstorm activity appears
probable. It remains a bit unclear the extent to which sustained
supercell development will be maintained, as opposed to convection
quickly growing upscale into one or more clusters/lines, but there
appears at least some potential for a few strong tornadoes, in
addition to large hail and potentially widespread strong to severe
wind gusts.

In the wake of this activity, into the middle to latter portion of
next week, convective potential becomes more unclear as strong flow
trends westerly, and broadly confluent across and east of the
Rockies, between broad mid-level troughing overspreading the
northern tier and broad mid-level ridging across the southern tier.
Another, initially notable, short wave perturbation emerging from
the southern mid-latitude/subtropical eastern Pacific is still
forecast to progress into the Southwest. But latest model output
suggests that it may become sheared while continuing across and east
of the southern Rockies, with only modest to weak surface
cyclogenesis currently forecast along a remnant frontal zone across
the southern Great Plains through Southeast.

..Kerr.. 04/24/2026

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ACUS48 KWNS 250857
SWOD48
SPC AC 250855

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0355 AM CDT Sat Apr 25 2026

Valid 281200Z - 031200Z

...DISCUSSION...
In the wake of a significant surface cyclone, which may be in the
process of migrating northeast of the upper Great Lakes region by
12Z Tuesday, it appears that a cold front will gradually advance
across the Atlantic Seaboard and into the Gulf coast vicinity before
stalling later this work week into next weekend. It appears that
this will occur coincident with the southwestward suppression of
subtropical ridging, initially centered over southern Mexico and
influential as far north as the Gulf coast at the outset of this
period.

Near the southern periphery of the westerlies/northern periphery of
the subtropical ridging, there appears a similar signal in both
ECENS and GEFS related medium-range guidance concerning potential
for organized severe thunderstorm development by late Tuesday
afternoon into Tuesday evening. An evolving pre-frontal corridor of
moderate to strong potential instability across the Ark-La-Tex
through Ark-La-Miss vicinity may provide a focus for an upscale
growing thunderstorm cluster, aided by forcing for ascent and shear
associated with a mid-level speed maximum progressing across the
region.

Through the remainder of the week, into early next weekend, the
lingering frontal zone across the Gulf coast region may provide a
focus for occasional continuing thunderstorm development,
particularly as an initially notable short wave perturbation,
emerging from the southern mid-/subtropical latitudes of the eastern
Pacific, progresses east of the southern Rockies. However, barring
more substantive frontal wave development than currently forecast,
potential for organized severe convection remains unclear.

..Kerr.. 04/25/2026

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