Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
850 PM EDT Tue Jul 7 2026

Day 1
Valid 01Z Wed Jul 08 2026 - 12Z Wed Jul 08 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE NORTHERN PLAINS, UPPER MIDWEST AND SOUTHERN MID-ATLANTIC...

...Mid Atlantic...

Elevated PWATs above 2" and the presence of a cold front across
southern and southeast VA has led to a focus of enhanced convection
across the area. Significant hourly rates are the driver behind any
flash flood prospect as weak shear coupled with modest buoyancy
allows for pulse type convection with slow cell motions. Outflows
generated by storms have allowed for local initiation of
thunderstorms considering how favorable the environment is across
the region. This setup is also conducive for heavy rain prospects
all the day into NC where current radar/sat composite indicate a
strong cluster of thunderstorms already impacting the Raleigh
metro. This will continue for another few hours before the loss of
diurnal instability will eventually degrade any activity in the
area. This goes for areas of VA as well, so the SLGT risk was
maintained in these areas with the best prospect for flash flooding
likely to occur in the window between 00-06z. The SLGT risk was
expanded to include the Raleigh metro due to the ongoing heavy
rainfall and flash flood warnings in effect with potential impacts
lingering for another few hours.

...Northern Plains to Upper Midwest...

Energetic shortwave analyzed upstream over eastern MT into the
western Dakotas will aid in the maturation of a round of strong to
severe thunderstorms across eastern ND/SD, extending through MN
with activity eventually propagating east and southeast into WI
overnight. CAMs have been consistent with the signature of this
convective initiation along a front draped over the region.
Increased convergence along the front will stem from a combination
of frontal enhancement and the nose of an 850mb LLJ entering into
the area. Flow aloft will align parallel to the front with shear
provided via a 50kt jet max at 500mb. Deep moisture pool across the
Northern Plains and Midwest is present with PWATs between
1.7-2.0", verified via the 00z KMPX sounding running at 1.93"
PWATs as of the 08/00z RAOB. HREF probs continue to highlight
central MN as the focal point, however, hourly CAMs such as the
HRRR have inferred that the area over northeast SD down through
south-central MN may end up as the primary target, or at least
provide a secondary maxima as they align within the quasi-
stationary front in place, and storm motions move into the warm
sector and better localized shear overnight. No matter the case,
the environment is ripe for locally enhanced rainfall with hourly
rates likely to reach 2-3"/hr in the strongest cell cores leading
to rainfall totals between 3-5" in spots across the region. More on
this setup can be reviewed with the latest MPD #0642 issued over
the area of interest. The previous SLGT risk was generally
maintained with just a minor expansion to the east in WI, and a
nudge south on the southern flank of the inherited risk.

Kleebauer
 

Day 2
Valid 12Z Wed Jul 08 2026 - 12Z Thu Jul 09 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE UPPER MISSISSIPPI VALLEY/UPPER GREAT LAKES...

20Z Update...
The previously issued outlook still in good shape. Even though
there were a couple of minor adjustments...there was no fundamental
shift in the forecast reasoning.

Previous Excessive Rainfall Discussion...

...Central Plains to the Upper Great Lakes...

Several locations remain sensitive given recent rains and lowered
FFGs, particularly for portions of the Upper Mississippi Valley and
Upper Great Lakes. A Slight Risk area remains warranted for this
part of the country where areal averages of 1-2 inches are expected
with localized swaths of 3+ inches. Convection from overnight may
be weakening during the morning hours however redevelopment near
the frontal boundary midday should occur over Minnesota and
Wisconsin. Approaching shortwave energy and an upper level jet
will help drive this uptick in activity, with PWs above the
climatological 90th percentile and CAPE approaching 2000 J/kg
supporting heavy rainfall rates. While a progressive squall line
should eventually evolve, there will be an opportunity for some
training and backbuilding during the development and initial
upscale growth phase of convection. A Marginal Risk spans from the
Central Plains to the Great Lakes and surrounding area.

...Tennessee/Ohio Valley to the Mid-Atlantic...

A Marginal Risk was maintained for this region. A shortwave moving
across Kentucky/Tennessee and a lingering backdoor front over
West Virginia/Virginia should both act as a focus for convective
development. Not expecting anything too organized or widespread,
but enough moisture and instability will be around to support
locally heavy rainfall rates.

Campbell


Day 3
Valid 12Z Thu Jul 09 2026 - 12Z Fri Jul 10 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE NORTHERN/CENTRAL PLAINS, MIDWEST, OHIO/TENNESSEE VALLEYS
AND GREAT LAKES REGION...

Stronger flow will initially remain along the northern tier of the
CONUS early to mid-week with mean upper-ridging across the western
to central United States. Embedded shortwaves rounding the upper-
ridge will eventually lead to deepening troughing across the the
Midwest and adjacent areas on Thursday. The southward shift of
stronger flow aloft into the Central Plains east through the Middle
Mississippi/Ohio/Tennessee Valleys and Lower Great Lakes will
bring a better chance for scattered thunderstorms across the
region.

Seasonably high instability and moisture pooling southward of a wavy
cold front will support locally heavy rainfall rates with training
potential over the region. That will compound impacts from
convection the previous forecast period. A large area of 1-2 inch areal
average totals with embedded higher amounts positioned over the
southern-third of Illinois/Indiana/Ohio through much of Kentucky
into West Virginia. This is coincident with the progression of both
the front and a strengthening shortwave trough migrating out of
the Central Plains into the region as we move into Friday. Machine
Learning output is also favoring the Ohio River Basin into the
Central Appalachians extended from southwestern Pennsylvania down
through West Virginia as terrain influences along with the synoptic
evolution will couple into a targeted threat for heavy rainfall
and local maxima sufficient for scattered flash flood prospects.

Bann
 

Day 4 and Day 5

Valid 12Z Fri Jul 10 2026 - 12Z Sun Jul 12 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE OHIO/MID-MISSISSIPPI VALLEYS AND CENTRAL APPALACHIANS ON
FRIDAY AND SATURDAY...

...Ohio and Mid-Mississippi Valley's...

20Z Update: The previous forecast was generally maintained with the
overall synoptic pattern still maintaining continuity in the
proposed evolution at both the upper levels and at the surface.
Ensembles continue to indicate a multi-day bout of heavy rainfall
across the Mid-Mississippi to Ohio Valley in conjunction with both
mid-level ascent and the proxy of a cold/quasi-stationary front
that will aid in scattered to widespread convective activity in-of
a very moist environment positioned over the region. The trends in
guidance indicate a bit more emphasis further west into MO with
even the D4 showing an extension of heavy rain prospects back into
the Southern High Plains thanks to a likely convective complex
developing around the eastern flank of a strengthening ridge over
the Four Corners. Classic summer pattern materializing for areas
west of the Mississippi, so the threat for isolated flash flooding
will likely have some footing in the extended with D4 the first
prospectus day for the threat. The SLGT risk inherited was expanded
into the Mid-Mississippi area of eastern MO on D4 and across
southern MO on D5 given the trends. The MRGL risk expands westward
into the Southern High Plains on D4.

Kleebauer

..Previous Discussion..

Stronger flow will initially remain along the northern tier of the
CONUS through mid-week with mean upper-ridging across the western
to central U.S. Embedded shortwaves rounding the upper-ridge will
eventually lead to deepening troughing across the the Midwest and
adjacent areas by Thursday. The southward shift of stronger flow
aloft will bring increasingly widespread storm chances from the
central Plains east through the Mississippi Valley into the
Ohio/Tennessee Valleys and central Appalachians. Seasonably high
instability and moisture pooling along a southward progressing,
wavy cold front will lead to multiple rounds of heavy rain-
producing storms later this week and into the weekend. Mean flow
generally parallel to the east-west oriented front will support
clustering/training storms increasing the threat for longer-
duration rainfall and higher totals. The embedded waves will help
to slow the frontal progression at times also helping to increase
the chance for repeated rounds/training of storms. For Friday (day
4), the latest guidance shows widespread areal average rainfall of
1-2" with good overlap between the ensemble means and AI guidance
favoring the Ohio/Tennessee Valleys into the central Appalachians,
where a Slight Risk has been maintained. While the guidance is not
quite as bullish on amounts yet on Saturday (day 5), a similar set
up will support additional locally heavy rainfall, with the concern
being that much of the mean/AI guidance overlaps similar regions
to Friday, favoring the middle to upper Ohio/Tennessee Valleys into
the central Appalachians. Given the increasingly wet antecedent
conditions expected from the prior days with additional storms
likely, another Slight Risk has been introduced.

Putnam

...Southwest U.S...

Monsoonal activity will finally make an appearance by the end of
the week with the threat ramping up into some more appreciable in
regards to magnitude and coverage across the terrain of
southeastern and central AZ, mainly following the Huachucas up
through the Mogollon Rim in east-central AZ. PWATs will surge north
along prevailing southerly flow on the western side of the broad
upper ridge centered over the Four Corners. QPF signatures are
textbook in monsoonal convection billowing up across the terrain at
lead which is a good indicator of at least the isolated threat of
flash flooding to kick off the Monsoon season across the Southwest.
A MRGL risk has been added to account for the threat on D5 with
perhaps an upgrade plausible on D4, but signals are not as prolific
on Friday compared to Saturday on both the global deterministic and
their ensembles.

Kleebauer
 

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