Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Sep 14 2025 08:09:33 FOUS30 KWBC 140809 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 409 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=20 portion into an upper low that will move onto the High Plains later this morning. Southerly flow will continue across the Northern=20 Plains along with ample moisture -- PW anomalies +2 to +3 sigma --=20 as a surface low over SD moves northward later this afternoon.=20 Convergent flow toward the nose of the sfc-based instability=20 gradient just to the east is expected to promote some south-to-=20 north convection that may overlap areas that saw a few inches of=20 rain on Saturday. Maintained the Slight Risk outline here with a=20 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=20 into its own entity and extended it even farther southward to the=20 Mexican border to account for another tick up in expected=20 convection from KS southward to TX. Storms should fire along and=20 ahead of a low-level confluence axis and within a stripe of deeper=20 moisture. Some of these areas in W TX saw a couple/few inches of=20 rain on Saturday and FFG values are lower. Some models do indicate=20 the potential for slow-moving or backbuilding cells, resulting in=20 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=20 MEXICO, THE CENTRAL PLAINS, AND COASTAL VIRGINIA... ....Southern New Mexico... Moisture will start to nudge upward over southern NM (though much=20 more well west of there) with some afternoon instability and=20 expected isolated convection, mainly over the mountains close to=20 the Mexican border. Low-end Marginal Risk is outlined here though=20 activity should be rather isolated.=20 ....Central Plains... Positively-tilted trough over the Northern Rockies will move=20 eastward to the High Plains Tuesday afternoon. Broad westerly mid-=20 level flow amid increasing moisture will help fire off some storms=20 over at least NE near the better forcing but also southward into=20 KS. A Marginal Risk is outlined here for an isolated flash flood=20 threat.=20 ....Coastal Virginia... Over the past couple of days, the models have trended toward=20 bringing in an area of low pressure near the Outer Banks Tuesday=20 morning or so. Rain should spread inland on Monday with additional=20 and perhaps heavier rain on Wednesday. This area has been rather=20 dry recently and rain rates may not be all that high, but some=20 convection-driven rain is possible depending on the flavor of this=20 area of low pressure. A Marginal Risk is depicted for=20 southeastern/coastal Virginia and far northeastern North Carolina=20 but with a lot of uncertainty in the rainfall=20 pattern/rates/duration.=20 Fracasso Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!9gTO1JLXMwzvJsAE_mYlWZMnFsR2Bd9wBC1DkiSlzWoX= vM52M_NqmFFfB47h_SbPmZSLFJRIGgTNlnEQdP7iBZz0pWo$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!9gTO1JLXMwzvJsAE_mYlWZMnFsR2Bd9wBC1DkiSlzWoX= vM52M_NqmFFfB47h_SbPmZSLFJRIGgTNlnEQdP7imv7DSOY$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!9gTO1JLXMwzvJsAE_mYlWZMnFsR2Bd9wBC1DkiSlzWoX= vM52M_NqmFFfB47h_SbPmZSLFJRIGgTNlnEQdP7igqiBvWs$=20 =3D =3D =3D To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. --- SBBSecho 3.28-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .