FOUS30 KWBC 140824
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
424 AM EDT Sun Sep 14 2025

Day 1
Valid 12Z Sun Sep 14 2025 - 12Z Mon Sep 15 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL IN THE WESTERN DAKOTAS...

...Northern Plains...

Upper trough exiting the Rockies has split off its southern 
portion into an upper low that will move onto the High Plains later
this morning. Southerly flow will continue across the Northern 
Plains along with ample moisture -- PW anomalies +2 to +3 sigma -- 
as a surface low over SD moves northward later this afternoon. 
Convergent flow toward the nose of the sfc-based instability 
gradient just to the east is expected to promote some south-to- 
north convection that may overlap areas that saw a few inches of 
rain on Saturday. Maintained the Slight Risk outline here with a 
Marginal Risk buffer extending to the south to the edge of the Sand
Hills.

...Central and Southern Plains...

Split the longer Marginal Risk area from the previous forecast 
into its own entity and extended it even farther southward to the 
Mexican border to account for another tick up in expected 
convection from KS southward to TX. Storms should fire along and 
ahead of a low-level confluence axis and within a stripe of deeper 
moisture. Some of these areas in W TX saw a couple/few inches of 
rain on Saturday and FFG values are lower. Some models do indicate 
the potential for slow-moving or backbuilding cells, resulting in 
locally heavy amounts and perhaps isolated flash flooding concerns.

Fracasso


Day 2
Valid 12Z Mon Sep 15 2025 - 12Z Tue Sep 16 2025

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Fracasso


Day 3
Valid 12Z Tue Sep 16 2025 - 12Z Wed Sep 17 2025

...THERE ARE MARGINAL RISKS OF EXCESSIVE RAINFALL IN SOUTHERN NEW 
MEXICO, THE CENTRAL PLAINS, AND COASTAL VIRGINIA...

...Southern New Mexico...

Moisture will start to nudge upward over southern NM (though much 
more well west of there) with some afternoon instability and 
expected isolated convection, mainly over the mountains close to 
the Mexican border. Low-end Marginal Risk is outlined here though 
activity should be rather isolated. 

...Central Plains...

Positively-tilted trough over the Northern Rockies will move 
eastward to the High Plains Tuesday afternoon. Broad westerly mid- 
level flow amid increasing moisture will help fire off some storms 
over at least NE near the better forcing but also southward into 
KS. A Marginal Risk is outlined here for an isolated flash flood 
threat. 

...Coastal Virginia...

Over the past couple of days, the models have trended toward 
bringing in an area of low pressure near the Outer Banks Tuesday 
morning or so. Rain should spread inland on Monday with additional 
and perhaps heavier rain on Wednesday. This area has been rather 
dry recently and rain rates may not be all that high, but some
convection-driven rain is possible depending on the flavor of this 
area of low pressure. A Marginal Risk is depicted for 
southeastern/coastal Virginia and far northeastern North Carolina 
but with a lot of uncertainty in the rainfall 
pattern/rates/duration. 

Fracasso
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