Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
413 AM EDT Wed Jun 10 2026

Day 1
Valid 12Z Wed Jun 10 2026 - 12Z Thu Jun 11 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
CENTRAL PLAINS AND MIDWEST...

.Midwest and Central Plains...
A strengthening cyclone will be moving northeast into south-
central Canada and push a cold front across the north-central
United States, which will trigger scattered showers and
thunderstorms ahead of and along the front. A warm front will lift
north ahead of the system, establishing a broad warm sector from
the central Plains to the Upper Midwest. The warm sector air mass
will be characterized by anomalously high moisture content, with
PWAT values rising to 1.75-2.25 inches. Increasing temperatures
and moisture will also result in increasing instability, with the
highest MUCAPE (> 3000 J/kg) expected to concentrate over eastern
Kansas, northern Missouri and eastern Iowa. Storms forming in this
area will have the potential to produce heavy downpours with
rainfall rates of 2-3 inches per hour, which would exceed FFG in
much of this region. Storms forming further north along the front
will also have the potential to produce locally heavy rainfall as
well. Instability should be sufficient for deep convection across
portions of Minnesota, Wisconsin, and Illinois, and convection may
become more organized this afternoon with increasing shear along
the frontal boundary.

There remains some uncertainty regarding where the heaviest
rainfall totals will be, but the HREF and RRFS generally agree on
an area of elevated totals from northern Illinois through
Wisconsin. This area will likely receive some locally heavy
rainfall this morning from an eastward propagating MCS out ahead of
the surface frontal boundary, then another wave of convection
should ignite across the region this afternoon as the front
approaches. For the central Plains, rainfall totals have generally
trended downwards over the past 48 hours, most likely due to a more
progressive frontal boundary that is oriented SW-NE instead of
W-E, reducing convergence across the region. The synoptic setup
should become more conducive for heavy rainfall over the central
Plains late tonight into early Thursday as a frontal wave develops
along the boundary and triggers an area of enhanced convection.
Moisture and instability will surge into the central Plains ahead
of this feature as a low level jet strengthens, which should
support efficient rainfall rates in excess of 2 inches per hour.
For these reasons, a Slight Risk of excessive rainfall extends from
northeastern Kansas and southeastern Nebraska to Wisconsin and
northern Illinois with a broader Marginal Risk area across much of
the east-central Plains and Midwest.

.Tennessee Valley and southern Appalachians...
An MCS is currently moving southeast across the Ohio Valley and
should move across the eastern Tennessee Valley and southern
Appalachians this morning. Rainfall rates up to 2-3 inches per hour
have been observed with this system overnight and will remain
possible as the system moves across eastern Kentucky. Convection
should weaken as the system is disrupted by the southern
Appalachians, but upslope flow may enhance rainfall totals over the
western Carolinas and western Virginia. Models have trended more
to the northeast with this MCS, resulting in a shift in the
Marginal Risk area, trimming out central Kentucky and most of
western Tennessee and expanding into western Virginia. Luckily,
rainfall from this system should be displaced from where heavy
rainfall was observed yesterday over central and western Kentucky,
but locally heavy rainfall may still lead to isolated instances of
flash flooding.

.Interior Northeast and Mid-Atlantic...
A surface low pressure system will track across southeastern
Canada today and lift a warm front across the Northeast. Upper
level troughing extending across the Northeast and Mid-Atlantic
will allow for a region of broad ascent that will support scattered
showers and thunderstorms. An anomalously moist air mass will push
into these regions behind the front, increasing PWAT values up to
around 2 inches (above the climatological 90th percentile), which
will allow for locally heavy rainfall with rates of 1-2 inches per
hour. Rainfall may also be enhanced by upslope flow over the
terrain in the Interior Northeast and central Appalachians. A
Marginal Risk of excessive rainfall covers portions of the Interior
Northeast, central Appalachians, Mid-Atlantic where isolated
instances of flash flooding will be possible.

.Southwest Florida...
Convection will ignite as the Atlantic and Gulf sea breezes
collide this afternoon over Southwest Florida. Southeasterly flow
will increase PWAT values across the Florida peninsula throughout
the day today, with the highest values (2.2-2.5 inches) focused
over South Florida. Given a very moist atmosphere with strong
convective forcing at the surface, thunderstorms will be able to
produce heavy rainfall rates. The latest HREF is showing high
probabilities (50-70%) of rainfall rates exceeding 2 inches per
hour, and hi-res CAMs suggest rainfall rates of 3-4 inches will be
possible in deeper convective cells. Rainfall rates this high will
likely create localized flooding concerns for urban areas in
Southwest Florida where there is a Marginal Risk of excessive
rainfall.

Dolan


Day 2
Valid 12Z Thu Jun 11 2026 - 12Z Fri Jun 12 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
MIDWEST...

.Southern Plains to Midwest...
The frontal wave that developed over the central Plains Wednesday
night will surge northeast and intensify as a strong trough swings
across the north-central United States. Strong southerly flow ahead
of this wave will drive an anomalously moist and highly unstable
air mass into the Midwest that will support enhanced convection
in the vicinity of the frontal wave. Showers and storms will also
form along the frontal boundary as it progresses, extending back
into the southern Plains, but the progressive nature of the front
should somewhat limit the flash flood potential over the Plains.
Moisture will pool ahead of the cold front as it surges
southeastward, creating a swath of high PWAT values of 2-2.5 inches
from the southern Plains to the Great Lakes that will support high
rainfall rates in excess of 2 inches per hour. Available CAMs and
global models show a broad area of heavy rainfall across the
Midwest, which is encompassed by a Slight Risk of excessive
rainfall, and the highest rainfall totals are expected to focus
over eastern Iowa, northern Illinois, and southern Wisconsin. These
areas will have the highest risk of flash flooding on Thursday,
especially after heavy rainfall in the Day 1 period. Additional
heavy rain falling on top of saturated soils will make these areas
more susceptible to flash flooding, and there could be a scenario
where a targeted upgrade to a Moderate Risk may be needed. A larger
Marginal Risk area stretches from the Midwest to the southern
Plains where heavy rain may lead to isolated instances of flash
flooding.

.Central Appalachians and Northeast...
An upper level shortwave trough is forecast to move southeast
over the Ohio Valley, Northeast, central Appalachians, and Mid-
Atlantic, which will trigger another round of scattered showers and
thunderstorms on Thursday. An anomalously warm and moist air mass
will be in place across these regions, with PWAT values of 1.75-2
inches, which will support rainfall rates of 1-2 inches per hour.
The upper level shortwave will result in an increasingly sheared
environment over the Northeast Thursday afternoon, which will allow
for some organized convection with higher rainfall rates in excess
of 2 inches per hour. These storms should move quickly, but
intense rainfall rates will support a risk of at least isolated
instances of flash flooding for portions of eastern Pennsylvania,
northern New Jersey, southern/central New York, and Connecticut
where a Marginal Risk of excessive rainfall has been introduced.
Another Marginal Risk area has been introduced over the central
Appalachians from West Virginia into southwestern Pennsylvania
where persistent northwesterly upslope flow will support enhanced
precipitation chances in this area. Soils will be somewhat
saturated from rainfall expected in the Day 1 period, and isolated
flooding concerns may continue into Thursday with showers and
storms capable of producing rainfall rates of 1-2 inches per hour.

Dolan


Day 3
Valid 12Z Fri Jun 12 2026 - 12Z Sat Jun 13 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM THE SOUTHERN
PLAINS TO THE NORTHERN MID-ATLANTIC...

A low pressure system tracking across Canada will push a cold front
across the eastern and south-central United States on Friday. As
the frontal boundary interacts with the anomalously warm and moist
air mass in place across the South and East, scattered to numerous
showers and storms are expected to develop. PWAT values around 2
inches will stretch from the southern Plains to the northern Mid-
Atlantic, which should support efficient rainfall rates. High shear
in the vicinity of the upper level trough over the Northeast and
northern Mid-Atlantic will likely allow for some strong, organized
convection with the potential to produce heavy downpours. Storm
motion across the East should be relatively quick given the
progressive nature of the front, but this will be the third
consecutive day of active convection for this region, which will
support a risk of at least isolated flash flooding. The tail end of
the front will become quasi-stationary over the southern Plains
with broad southeasterly flow on the southern side of the
boundary. Warm, moist air will support convection with locally
heavy rainfall along the front, and convection may be enhanced
Friday evening as an upper level shortwave moves east across the
southern Plains. Showers and storms will likely extend west into
New Mexico where precipitation chances may be enhanced near the
Guadalupe and Sacramento Mountains. Locally heavy rainfall could
also pose a flood risk for burn scars in eastern New Mexico. A
Marginal Risk of excessive rainfall stretches from the southern
Plains to the northern Mid-Atlantic to cover these threats.

Dolan


Day 4 and Day 5
Valid 12Z Sat Jun 13 2026 - 12Z Mon Jun 15 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE CENTRAL AND SOUTHERN PLAINS AND MISSISSIPPI VALLEY THIS WEEKEND...

Active weather is anticipated across the Central/Southern Plains
and MS valley this weekend as a favorable environment for heavy
rainfall rates and training convection evolves southward. On
Saturday, a Slight risk of excessive rainfall continues for
portions of eastern KS, northeast OK, northwest AR and much of MO.
A strongly unstable airmass with CAPE locally over 3000 J/kg is
forecast to overlap with an increasing plume of above average
moisture. Large scale ascent focused within the right entrance
region of an upper level jet and amplified by subtle shortwave
features will interact with a corridor of strong 850mb moisture
transport. Given the resulting wind profiles, weak Corfidi vectors
are probable, favoring backbuilding and cell training. This results
in rather high confidence in some flash flood impacts, although
some spatial uncertainty persists. For the moment the Slight risk
area encompasses the region of best clustering in the multi model
ensemble (GEFS/ECENS/CMCE/AIFS ensemble).

On Sunday the threat of excessive rainfall shifts southward into
the Southern Plains and Lower MS Valley, targeting northeast TX,
central and eastern OK, northern LA, and much of AR. While the
overall environment remains similar to the previous day, deep
layer moisture is forecast to increase further, with PW values well
over the climatological 90th percentile expected. This environment
will remain supportive of high rainfall rate flash flood impacts,
although confidence in placement is lower due to some notable model
spread. The deterministic AIFS and AIGFS represent the farthest
south solutions, bringing the heaviest rainfall all the way towards
the TX Gulf Coast. However, traditional global ensemble clustering
remains further north, and even the AIFS ensemble mean is a bit
north of its deterministic run. The current Slight risk area
focused across the ArkLaTex region is where the full ensemble suite
(AI and physics based) shows the most overlap at this time.

Chenard


Day 1 threat area: www.wpc.ncep.noaa.gov/qpf/94epoints.txt
Day 2 threat area: www.wpc.ncep.noaa.gov/qpf/98epoints.txt
Day 3 threat area: www.wpc.ncep.noaa.gov/qpf/99epoints.txt