Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
857 PM EDT Thu Jul 30 2026
Day 2
Valid 12Z Fri Jul 31 2026 - 12Z Sat Aug 01 2026

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

...2030z Update...

The inherited slight risk was expanded into central Iowa/Missouri
and the Chicago Metro area based on the latest hi-res trends.
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.

The marginal in the Southwest remains unchanged, however 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.

Kebede

...Previous Discussion...

...Central US system...
Shortwave energy initially moving eastward out of the Northern
Rockies and adjacent High Plains will be accompanied by showers and
thunderstorms as the Day 2 period begins at 12Z on Friday. The
system will start taking a southward track in response to upscale
ridging across Montana and nearby areas of southern Canada. The
placement of the Marginal and Slight risk areas were similar to the
previous outlook and saw little reason to stray far from the
adjustments that were made on Wednesday because there was still
good agreement with where the synoptic scale forcing will be
greatest. 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...
Locally heavy to excessive rainfall remains possible along and near
an east to west oriented quasi-stationary front. 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. As a result, no changes to the Marginal Risk area
already issued.

...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 AZ 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.

Bann


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