FOUS30 KWBC 130736
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
336 AM EDT Sat Jun 13 2026

Day 1
Valid 12Z Sat Jun 13 2026 - 12Z Sun Jun 14 2026

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR SOUTHWESTERN MISSOURI...

In coordination with SGF/Springfield, MO and EAX/Pleasant Hill, MO
forecast offices, the Moderate Risk was shifted south out of the
Kansas City metro with this update, but expanded southeast to cover
more of the Missouri Ozarks. CAMs guidance of the QPF footprint for
the day has followed a very common pattern, which is to shift the
heaviest rainfall totals southward. Thus, it appears the greatest
flash flooding threat has shifted out of the Kansas City metro.
This is most certainly not to say that the flooding threat has
reduced to zero for the Kansas City metro, which remains in a
higher-end Slight, but that the greatest impacts from flash
flooding due to heavy rainfall are no longer expected to reach
Moderate Risk thresholds in the Kansas City metro. However, not far
to the south, the threat remains significant.

Training thunderstorms are expected to begin across Missouri this
afternoon. The training and overall coverage of the thunderstorms
will increase during the evening with the usual diurnal
strengthening of the low-level jet. This will pump abundant
tropical moisture into Missouri from the southwest on 40+ kt winds
at 850 mb. Since the line of storms is expected to align northwest
to southeast, the storms will be orthogonal to that southwesterly
flow, which will be essential for the continued redevelopment and
training of additional convection as the cells within the line
track southeastward. Once the storms reach around the Arkansas
border, the low level jet weakens significantly. This should allow
for breaks to develop in the line from Arkansas into Tennessee,
which will greatly diminish the flash flooding threat in those
states. The topography of the Ozarks across southern Missouri
supports a heightened flash flooding threat as the mountains
quickly funnel the heaviest rains into narrow valleys, worsening
the impacts of any flooding that develops there. This fact too
supports the southeastward expansion of the Moderate Risk area.

Meanwhile, a strong cold front will push southeastward out of the
Plains and eventually into Missouri. This front will end all of the
rain from northwest to southeast. This too supports the south and
eastward shifting of the greatest flash flooding threat. While
portions of far eastern Kansas still will have a threat for
extended periods of heavy rain, the advancing front reaching those
areas before points further east should also reduce the time heavy
rain will impact eastern Kansas, allowing for the Moderate to be
trimmed a bit. That said, there remains considerable uncertainty as
to how far east the best lines of training thunderstorms will set
up, so far eastern Kansas remains in an elevated threat for flash flooding.

Guidance has come into better agreement that the heaviest rains
will occur over Missouri today and tonight, and will struggle to
continue further north and east. Thus, the inherited Slight Risk
area over Iowa, most of northern Illinois, and all but the
southwestern tip of Indiana was downgraded to a Marginal Risk with
this update.

...Florida...

A Marginal Risk area was introduced with this update for all of the
Florida Peninsula. Abundant moisture and slow-moving thunderstorms
are expected to develop all up and down the Peninsula this
afternoon. Since the storms will be stationary, it stands to reason
that the most heavily impacted areas will see extended periods of
heavy rain. HREF neighborhood probabilities for over 3 inches of
rain are over 70% for the entire Peninsula. Thus, while the urban
areas on both east and west coasts are more flood-prone and are
likely to miss out on the heaviest rains, any urban areas such as
Orlando in the middle of the Peninsula could have isolated
instances of flash flooding.

Wegman


Day 2
Valid 12Z Sun Jun 14 2026 - 12Z Mon Jun 15 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR AREAS FROM
SOUTHERN NEW MEXICO THROUGH WESTERN MISSISSIPPI...

A slow-moving but potent cold front will approach portions of north
Texas through into Arkansas on Sunday. The MCS that caused the
Moderate Risk flooding in Missouri Saturday night will be
responsible for the heavy rains that elevate northeast Texas
through the lower Mississippi Valley into the Slight Risk
category. Associated heavy rain will be ongoing at the start of the
period Sunday morning, and will weaken and dissipate by midday.
Since the forward/southward progression of the heavies rains will
slow after daybreak Sunday, some areas may see several hours of
weakening but still heavy rains. Abundant moisture will remain in
place south of the front, as PWATs rise as high as 2.25 inches.
Thus, any cells producing rains will have no trouble doing so
efficiently. During the afternoon and evening, this area may see
additional widely scattered storms with the strong front stalled
out in the area, but coverage will be somewhat in question as the
stalled out front alone will not be enough forcing due to flow on
either side of the front weakening to light and variable winds.

Further west into west Texas and New Mexico, a shortwave trough
running into some of the same Gulf moisture as further east should
allow for scattered showers and thunderstorms to develop in
clusters from the afternoon well into the evening. Topographic
assistance by the Sacramento Mountains and other ranges may locally
produce heavy rains, where any burn scars may take over at raising
the flash flooding risk. The same front extends into the
Appalachians and interior Northeast. While the storms will be
racing in these areas, the abundance of moisture advecting north
into the front will support the storms in their capability of
producing heavy rainfall. The Marginal Risk for these areas was
expanded along the Canadian border through northern Maine.

The Marginal for portions of the Mid-Atlantic was split into 2
areas with this update. One for the I-95 corridor from DC to
Philly, and a second for the Hampton Roads area. Abundant
Gulf/Atlantic moisture in these areas will support fast-moving but
training storms capable of producing heavy downpours. Due to
ongoing drought, the threat really is focused on the urban areas
where FFGs are lower. The intermediate rural areas were removed
with this update as any training storms that occur over most of the
Delmarva will be over rural and flood-resistant/flat areas.

Wegman


Day 3
Valid 12Z Mon Jun 15 2026 - 12Z Tue Jun 16 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
LOWER Mississippi VALLEY TO EASTERN TEXAS...

A large, half-continent sized upper level low over northern Ontario
will spin numerous shortwaves around its periphery over the eastern
2/3 of the country. The jet stream will coincide with a strong but
stalled out cold front over north Texas and southern Arkansas. To
the south of that front, Gulf moisture will pool to well-above
normal levels, with PWATs to 2.25 inches over east Texas and
northern Louisiana. When the shortwaves track over that cold front,
it will both allow it to continue drifting southward, but also
provide sufficient upper level forcing to trigger numerous and
persistent thunderstorms along the east-west oriented front and
south. This will support an extended duration of training storms,
especially from east Texas through southwest Mississippi. A
higher-end Slight remains in effect for this area. The inherited
Slight was trimmed out of south-central Texas and central Alabama
on the west and east ends, but expanded north-south over Louisiana
through the Houston Metro. Rainfall totals in some areas could
easily exceed 6 inches, with totals to 10 inches in localized areas
possible due to the extended duration of heavy rain, especially
along the Texas/Louisiana border. The area remains in a higher end
Slight for now primarily due to very high FFGs and dry soils in the
area, but further increases in rainfall, especially as this period
moves into the CAMs range, could allow for a Moderate Risk upgrade
due to the very high rainfall amounts forecast for some areas.

Wegman


Day 4 and Day 5

Valid 12Z Tue Jun 16 2026 - 12Z Thu Jun 18 2026

...A SLIGHT RISK OF EXCESSIVE RAINFALL EXISTS FOR PORTIONS OF THE
CENTRAL GULF COAST...

The first half of the medium range will see two particular threats
for flash flooding. First, along the Gulf Coast, a stationary
front will work in tandem with with tropical moisture to develop
thunderstorms capable of torrential downpours both on Day 4
(Tuesday) and Day 5 (Wednesday). There is greater confidence in
Tuesday's flash flood threat given better model agreement in
placement of QPF and the nearby frontal boundary remaining strong
enough to help trigger numerous showers and thunderstorms. PWs
will remain above 2.0" in many cases as well, allowing developing
thunderstorms to contain highly efficient rainfall rates. Soils
will be more saturated in wake of Monday's thunderstorms as well,
making the region more susceptible to flash flooding. The forecast
remains largely on track for Tuesday (Day 4) with only some minor
tweaks to the inherited Marginal and Slight Risks to more closely
resemble the latest WPC QPF. By Wednesday (Day 5) the frontal
boundary will undergo frontolysis and the source of lift at the
surface will weaken. However, ensemble guidance continues to show
ample tropical moisture along the Central Gulf Coast, which at by
Wednesday will have dealt with multiple rounds of Excessive
Rainfall. A Marginal Risk was introduced along the I-10 corridor
from the Houston metro on east to the FL Panhandle to account for
the flash flood potential around the more urbanized communities
along the central Gulf Coast.

Farther north, Wednesday looks like an active day from the Midwest
on east into the OH Valley. A 500mb shortwave trough racing east
towards the Great Lakes late Wednesday will provide healthy upper-
level ascent aloft to foster the development of low pressure.
Meanwhile, a strengthening LLJ will direct anomalous moisture
located over the South northward into the region. NAEFS shows an
impressive IVT for mid-June that surpasses 750 kg/m/s over the
eastern Corn Belt that will provide copious amounts of moisture.
Guidance is not in agreement yet as to which locations are most
favored to witness the heaviest thunderstorm activity. Fast storm
motions should also help to limit residency times of developing
storms. That said, PWs ranging between 1.75-2.0" will be the norm
late Wednesday with storms likely containing efficient rainfall
rates. A Marginal Risk was introduced to account for the localized
flash flood potential on Wednesday from the Middle MS River on east
into the OH Valley.

Mullinax
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