FOUS30 KWBC 240804
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
404 AM EDT Thu Jul 24 2025

Day 1
Valid 12Z Thu Jul 24 2025 - 12Z Fri Jul 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM THE CENTRAL
AND SOUTHERN HIGH PLAINS INTO THE MIDWEST...

...High Plains into the Midwest...

Active pattern across the Central CONUS continues through Thursday
with another round of heavy convection likely in proximity to a
steady moving cold front from the north. At the surface, cold front
analyzed over the Northern Plains and Upper Midwest will make
headway to the south and southeast with a greater latitudinal push
west of the Mississippi due to a strong sfc-500mb ridge axis
nestled across the Southeastern U.S. The general southwest to
northeast alignment will be precursor to the expected mean cell
motions for the period with emphasis on convective development
likely from the OK panhandle up through KS/MO/IL/IA during the
late-afternoon and evening time frame. Initial impacts will be felt
further north in the first 6hr window of the period, but the
forward propagation of the convective cluster migrating out of
IA/NE should lose some strength in the morning as LLJ weakens and
cold pools run out ahead of the main bulk of precip. Still, some
embedded heavier cores could cause issues along and north of I-80
latitude leading to a MRGL and SLGT risk maintenance over eastern
IA into northern IL. 

As we move into the afternoon and evening, attention will turn to
the southwest from the initial impact areas with a broader focus
over northeast NM and points northeast through KS/northwest MO as
the next round of heavy convection takes shape. A sharp theta_E
gradient will likely denote the position of the cold front with
a long run of surface-850mb convergence located within the confines
of the front as it bisects the above areas. Surface low off the
High Plains of southeast CO will slowly move east-northeast into
the High Plains of KS by late-afternoon allowing for a maturing
south to southeast in-flow within the eastern flank of the low
which will set the stage for ample moisture pooling and
strengthening low-level convergence signature referenced above.
Convection will fire under the low's influence across southwest KS
into the adjacent OK/TX panhandles with mean cell motions
relatively weak within the low's proximity. Further to the
east, general destabilization in the warm sector will further 
convective development over eastern KS into northwest MO with 
increasing training potential as Corfidi vectors indicate a 
weakening upshear wind profile as we move into the evening,
especially in the confines of the front. 

Heavy rainfall potential is elevated due to the deep moisture
presence across the Central and Southern Plains with a strong
consensus in both deterministic and ensembles for >2" PWATs located
over central and eastern KS up into the northern half of MO. 00z
HREF neighborhood probs for >3" are between 50-80% over a large
portion of KS with the highest probs over northeastern KS near
Topeka and along the I-70 corridor. Probs for >5" are running
between 20-35% for the same areas. Areal average of 2-3" is fairly
pronounced within the means, but the key is some of the deterministic
from CAMs, and even some of the globals are indicative for local 
maxima between 4-7" with even a few 8+" thrown in for good measure.
This setup is one that could entice an upgrade in future updates 
with the highest potential likely over eastern KS into northwest MO
due to wetter antecedent soils and lower FFG's compared to areas 
back into southwest KS. That being said, this is one setup to keep 
a close eye on as locally significant flash flood potential is 
becoming more favorable as we step through the forecast cycles. If 
the probs trend even more favorable, there would be merit to see a 
targeted upgrade. For now, a broad SLGT risk with high end SLGT 
embedded over eastern KS into MO. 

...Central and Southern Rockies...

Isolated to widely scattered convection will initiate, once again
across the Front Range back into the Central and Southern Rockies
with localized maxima likely contributing to scattered flash flood
prospects in their wake. The primary ascent pertains to the
diffluent area ahead of the closed reflection over CA through the 
forecast period. Enough of a deep moisture presence and modest 
instability up through the Continental Divide and points east will 
be suitable for another day of convection with the best opportunity
for flash flooding likely located in proximity of the complex 
topography centered over northern NM through CO and southeast WY.
HREF probs indicate a general 1-3" type maxima in any cells that
develop which would bring a threat for local flash flood concerns,
similar to the past few days. The good news for today is the deeper
moisture presence will be less pronounced, so seeing a downward
trend in the potential overall. In any case, still enough for one
more day of impacts lead to MRGL risk continuity from previous forecast.

...Southeast...

The presence of a slow-moving surface reflection and eastward
progressing upper trough across the northern Gulf will lead to
another period of heavy rainfall within the confines of the
Southeast CONUS. Greatest opportunity will lie along the central
Gulf coast where the proximity of the surface low and attendant
surface trough could allow for short periods of convergence in-of
areas along and south of I-10 from LA back into the FL panhandle. 
Guidance remains inconsistent on any organized convective placement
with a smattering of heavy QPF bullseyes anywhere along the Gulf 
coast with even some extending back up through the GA and portions 
of the Carolina's. With PWATs remaining up inside the 90-99th 
percentile along the immediate coast and suitable instability 
presence, the previous MRGL was maintained with general continuity.

...Northern California and Adjacent Areas...

A narrow tongue of elevated moisture on the northern periphery of a
closed upper reflection along the CA coast will lead to a period of
convective development within the northern Sierra's through
northern CA and southern OR. PWATs running ~1 standard deviation
above normal and MUCAPE between 500-1000 J/kg should be sufficient
for scattered convective initiation along the ridges which could
easily produce local 0.5-1+" of precip in a short time. Given the 
favorable pattern into the terrain still dealing with remnant burn 
scars and complex drainage, the risk for at least isolated flash 
flooding still has merit. The previous MRGL risk was generally 
maintained with only minor adjustments.

Kleebauer
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