FOUS30 KWBC 310819
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
419 AM EDT Fri Jul 31 2026

Day 1  Valid 12Z Fri Jul 31 2026 - 12Z Sat Aug 01 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
MID TO UPPER MISSISSIPPI VALLEY AND VICINITY...

...Central US system...

Ridging across Montana and the Canadian Prairie will direct
shortwave energy southeastward spreading showers and thunderstorms
through the north-central and central states during this period.
Moisture (2"+ & 99th+ percentile PWATs) will be sufficient enough
to produce efficient rain rates, however, higher instability may
not make its way far enough north to help realize higher rates.
Flash flood guidance around 1" will allow for any convection/heavy
rainfall to potentially produce flash flooding. A Slight Risk area
encompasses southeast Minnesota, southern Wisconsin, Illinois,
western Indiana, northwest Kentucky, eastern Missouri and
central/eastern Iowa. The southern portion of the Marginal risk
area remained closer to the placement of greater instability which
would support higher intensity rainfall rates. Any downpours across
that region may at least have a chance at challenging the flash
flood guidance.

...Central Gulf Coast Region into parts of the Southeast...

A quasi-stationary front will be orientated in the west-east
fashion across the Gulf Coast region and will be a focus for locally
heavy to excessive rainfall. Deep- layer moisture and instability
should be more than sufficient and the guidance shows sufficient
effective bulk shear (0-6km magnitudes generally over 20 kts) for
more organized/persistent convective organization.

...Four Corners States into the Southern-Central High Plains...

Monsoonal flow and anomalous deep-layer moisture will keep the
potential for isolated instances of excessive rainfall across
portions of eastern Arizona and much of New Mexico into Colorado.
The areal coverage may be less than in preceding days given the
expansion of the sprawling upper ridge. Diurnal monsoonal
convection that develops over northeastern New Mexico is expected
to dive south and generate isolated to scattered flash flooding in
eastern portions of the state.

Campbell/Bann
 

Day 2  Valid 12Z Sat Aug 01 2026 - 12Z Sun Aug 02 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FRIDAY ACROSS
PARTS OF THE UPPER MIDWEST TO MID MISSISSIPPI VALLEY...

...Ohio/Tennessee Valley...

A potent low pressure system will supply plentiful instability to
the Great Lakes/Ohio and Tennessee Valleys region beneath a
deepening positively tilted mid-level low. PW values of 2+ standard
deviations above average (2-2.25 inches) will be advecting into
the region to support enhanced rainfall. A Slight Risk remains in
effect from eastern Illinois to Ohio and southward to Alabama and
Georgia. A broad Marginal Risk spans from Wisconsin to western New
York south to the eastern Gulf Coast and Southeast.

...Central Gulf Coast Region into parts of the Southeast...

Heavy rainfall threat will continue over this region along the
southern periphery of the full-latitude trough, south of the
quasi-sationary front. Deep-layer moisture and instability should
be more than sufficient, especially when coinciding with the weak
upper forcing (upstream upper trough w/ embedded convectively-aided
shortwaves), for more organized/persistent convective organization.

...New Mexico...

During this period general storm motion is expected to be from
north to south into an increasingly moist environment (1"+ and
97.5th percentile PWATs) and relatively saturated soils from Friday
storms will contribute to the flash flooding threat. A Slight Risk
was maintained for portions of central/eastern New Mexico with a
Marginal Risk area stretching from southeast Arizona to western
Texas and northward to southern Colorado.

Campbell/Kebede
 

Day 3  Valid 12Z Sun Aug 02 2026 - 12Z Mon Aug 03 2026

..THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE NORTHEAST...

...Upper Midwest to Northeast and Mid-Atlantic region...

The potent mid-level cyclone will continue to track to the east
during this period ushering the showers and thunderstorms along
with it into the Lower Great Lakes and Northeast region. Streaks of
heavy rainfall are also expected to develop across parts of the
Mid-Atlantic/North Carolina region. Some of these cells will have the
potential to yield 2 inches over a short period during the
afternoon and evening hours. A broad Marginal Risk spans from the
North/South Carolina border northward to New York and Lower
Michigan. A Slight Risk area covers extreme southeast Michigan,
northeast Ohio, northern West Virginia, western Pennsylvania and
western New York.

...Southeast...

Showers and thunderstorms will persist along the stalled frontal
boundary thus maintaining an elevated threat for heavy rainfall and
potential for local flash flooding. Therefore, a Marginal RIsk area
was maintained for eastern Gulf Coast/northern Florida and southern Georgia.

...Southwest...

Monsoonal moisture will continue to drive convection across
portions of New Mexico and Arizona. Locally heavy rainfall may
continue to result in isolated flash flooding across the region. A
Marginal Risk area is in effect for southern Arizona and southwest New Mexico.

Campbell
 

Day 4 and Day 5  Valid 12Z Mon Aug 03 2026 - 12Z Wed Aug 05 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM THE NORTHERN
MID ATLANTIC INTO SOUTHERN NEW YORK STATE AND SOUTHERN NEW ENGLAND...

The well defined upper trof moving through the Ohio Valley day 3,
will begin to split into two pieces day 4. While there are
differences with the details with this upper trof evolution, there
is agreement that an axis of anomalous PW values, 2+ standard
deviations above the mean, 2 to 2.25" PW values, will stretch from
North Florida, northeastward across the coastal Southeast, Mid-
Atlantic and from eastern NY State into New England. Generally
favorable right entrance region jet dynamics will accentuate lift
in this anomalous PW axis, supporting potential for locally heavy
rainfall totals. A slight risk was added over portions of the
northern Mid-Atlantic into southern NY State and southern New
England where recent heavy rains have lowered FFG values. A
marginal risk extends southward through the remainder of the Mid-
Atlantic into the Southeast where locally heavy rains are also
likely but FFG values are higher.

For both day 4 and day 5...a marginal risk was depicted for
monsoonal convection across southern Arizona into New Mexico. Not a
lot of confidence with qpf details here, but locally heavy rains
and isolated runoff issues possible in the above average PW values
expected across this area.

Day 5...the closed low over the Upper OH Valley will become nearly
stationary day 5. An area of anomalous PW values will remain to the
east of this closed low, across the Upper OH Valley into the Mid-
Atlantic, Southern New England and south into the coastal southern
Mid-Atlantic. A broad marginal risk area was depicted in this
anomalous PW axis for locally heavy rains and isolated runoff
issues. The surface front moving through New England day 4, may
become stationary and west to east oriented across southern New
England into the northern Mid-Atlantic day 5. A few models are
showing more defined heavy rains in the vicinity of this front
where there is potential for persistent south southwesterly inflow.
Still a lot of spread with qpf details, warranting only a marginal
risk at this time, with changes possible with future updates.

A surface front expected to push southeastward day 5 from the Upper
MS Valley into the Upper Lakes and south through the Central
Plains. There is model consensus for an axis of potentially heavy
rains from Nebraska, eastward into Iowa and southern MN where the
front may become more west to east oriented late Tue into early
Wed. Moist southerly low level inflow into the front at this time
may support organized convection, heavy rains and isolated runoff issues.

Oravec
$$
--- MultiMail/DOS
 * Origin: capitolcityonline.net * KY, USA (618:250/10)