Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Feb 17 2025 19:00:35 FOUS30 KWBC 171900 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 200 PM EST Mon Feb 17 2025 Day 1 Valid 12Z Mon Feb 17 2025 - 12Z Tue Feb 18 2025 The probability of rainfall exceeding flash flood guidance is less than five percent. Gallina Day 2 Valid 12Z Tue Feb 18 2025 - 12Z Wed Feb 19 2025 ....THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ALONG PORTIONS OF THE CENTRAL GULF COAST... ....21Z Outlook Update... Recent models (and particularly CAMs) depict substantially increased rainfall potential (into the 2-4 inch range) late=20 Tuesday into early Wednesday across southern Louisiana, with a=20 greater focus for training convection near Lake Charles=20 around/after 00Z. A Slight Risk was considered for this update, but concerns about antecedent ground conditions (dry soils, lack of=20 rainfall) and confidence in the specific axes of heavier rainfall=20 were mitigating factors. The Marginal Risk was expanded=20 northwestward toward east Texas and west/northwest Louisiana where=20 soils were wetter and convergence on the nose of 850mb flow could=20 result in a few heavier downpours and isolated runoff issues. See the previous discussion below for more information. Cook ....Previous Discussion... Strengthening southwesterly winds ahead an amplifying upper level shortwave and an associated cold front are expected to draw deeper moisture into parts of the Gulf Coast, with PWs climbing to around 1.5 inches. This moisture along with increasing lift and instability may be sufficient for heavy rainfall rates. Models offer a modest signal for training storms ahead of a surface low that is forecast to develop and advance east along the coast Wednesday morning. This may help support localized heavy rainfall, with some potential for isolated flash flooding, especially in urbanized areas. Pereira Day 3 Valid 12Z Wed Feb 19 2025 - 12Z Thu Feb 20 2025 ....THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF NORTHERN FLORIDA AND SOUTHERN GEORGIA... ....21Z Outlook Update... A convective complex should be ongoing across southeastern Louisiana and adjacent north-central Gulf waters at the beginning=20 of the forecast period. This complex will migrate eastward toward the Florida Panhandle and vicinity throughout the morning hours, although heavier rainfall should remain offshore due to a lack of inland instability. Light/modest rain rates are expected across most of the Southeastern U.S. downstream of the complex, and models have trended lower with QPF especially through northeastern Florida. Given the latest trends, the Marginal Risk previously in effect has been confined to areas from southeastern Louisiana through the western Florida Panhandle closer to where the best instability should=20 reside. See the previous discussion for more information. Cook ....Previous Discussion... Surface low developing along the central Gulf Coast on Day 2 will=20 continue to track east early in the period, before tracking=20 northeast along the Southeast Coast later in the day. Training=20 storms, with potentially heavy rainfall rates fueled by deep=20 moisture (PWs 1.5-1.75 inches) ahead of the wave and along its=20 trailing cold front, may produce locally heavy amounts and an=20 isolated flash flooding threat on Wednesday. Pereira Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!52GLp0Cnam_szxdJF7tIFdVyR_Z1KM0SqWz9066vX0PQ= nnYH_CW1Cn862womsR1PVI6xY_pqnk8TsU0M1tToxUM8cYA$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!52GLp0Cnam_szxdJF7tIFdVyR_Z1KM0SqWz9066vX0PQ= nnYH_CW1Cn862womsR1PVI6xY_pqnk8TsU0M1tToyyl9oO0$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!52GLp0Cnam_szxdJF7tIFdVyR_Z1KM0SqWz9066vX0PQ= nnYH_CW1Cn862womsR1PVI6xY_pqnk8TsU0M1tTomGMPQEk$=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 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .