FOUS30 KWBC 281946
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
346 PM EDT Mon Jul 28 2025

Day 3
Valid 12Z Wed Jul 30 2025 - 12Z Thu Jul 31 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE MIDDLE MISSISSIPPI VALLEY AND FOR PORTIONS OF THE FRONT RANGE
AND ADJACENT HIGH PLAINS...

...Mid MS Valley...

21Z update... The area highlighted for the Slight Risk area remains
in good order, only minor reshaping of the boundary made to reflect
the latest WPC QPF and model trends.

Campbell

At 12z Wednesday it seems likely that we will have some degree of
organized convection ongoing in the vicinity of IA, although at
this lead time getting these specifics right is tricky.
Nonetheless, it appears probable that a better defined
shortwave/MCV will be associated with this convection and slowly
move east across IA/MO/IL and vicinity Wednesday into Wednesday
night. Meanwhile we will have a slowly southward shifting cold
front helping focus convergence, and the right entrance region of
the upper jet adding some divergence aloft. With plentiful CAPE
near the front and PWs locally over 2", the ingredients for areas
of excessive rainfall are in place. Some uncertainty remains on the
details...but 00z models are coming into a better consensus on the
favored axis for heavy rainfall..generally stretching across
portions of IA, northern MO and into central/northern IL and
possibly portions of IN.

...Southwest and High Plains...

21Z update... There is a growing signal for convection to fire up 
along the Front Range and the adjacent high plains. The nature of
coverage still seems to be scattered however guidance has  
consensus of 1 to 2 inches for areal maximums with isolated
locations potentially reaching 3 inches or higher. In coordination
with the local forecast offices, opted to raise a Slight Risk for 
eastern Colorado, southeast Wyoming, western Kansas, small portions
of the Oklahoma and Texas Panhandles, and northeast New Mexico.

Campbell

Isolated to scattered convection will likely develop near areas of
terrain from NM into the Rockies. Generally not looking like the
greatest forcing, so the degree of convective organization remains
unclear. At the moment most models indicate mostly
isolated/scattered development, and generally not enough coverage
for anything more than a Marginal risk. However there is some
potential for a few organized clusters to move off the terrain
into the High Plains, and so can not rule a targeted Slight risk or
two as we get closer in time and have more high res guidance to
interrogate.

...Elsewhere...

A broad Marginal risk extends from the central Gulf Coast all the
way into portions of New England. High PWs and CAPE and convective
coverage will drive the risk from the Gulf Coast into the TN
valley. A lack of organization may keep FFG exceedance coverage
down, but high rainfall rates will likely locally approach or
exceed FFG. A cold front will drive the risk form portions of the
OH valley into New England. Generally quick cell motions and the
lack of a significant QPF footprint in the 00z models keep this
risk at a Marginal level.

Chenard
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