Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Aug 13 2025 06:49:24 AWUS01 KWNH 130649 FFGMPD FLZ000-ALZ000-MSZ000-131200- Mesoscale Precipitation Discussion 0920 NWS Weather Prediction Center College Park MD 248 AM EDT Wed Aug 13 2025 Areas affected...Portions of the Central Gulf Coast Concerning...Heavy rainfall...Flash flooding possible Valid 130647Z - 131200Z Summary...Showers and isolated thunderstorms will train onshore through morning from eastern MS through the western FL Panhandle. Rainfall rates within these tropical downpours will reach 3"/hr at times, which through training could produce stripes of 2-4" of rain. Flash flooding is possible. Discussion...The regional radar mosaic early this morning shows a rapid expansion of tropical showers with isolated thunderstorms aligned south to north in the vicinity of Mobile Bay, AL. This expanding convection is associated with a weak surface trough extending across the area, with upstream onshore flow from the Gulf drawing impressive moisture northward. The greatest instability (MUCAPE above 1000 J/kg) is confined to the immediate coast, and this has been the demarcation of the heaviest rainfall rates so far this morning, but PWs above 2 inches extend all the way into northern AL, with recent GPS measured PWs reaching 2.4 inches near Mobile Bay. These extreme PWs and warm cloud depths over 15,000 ft have been supporting efficient warm-rain collision processes, with MRMS 15-min rainfall measured as high as 0.7 inches (3"/hr) already in some of the cells training onshore. The high-res CAMs are actually in pretty good agreement both with the footprint and amount of the expected rainfall through around 12Z, focusing from the AL/MS border eastward towards the Emerald Coast of the Florida Panhandle. Here, 850mb winds measured via current VWPs have already reached 15-25 kts, exceeding the mean wind of 10-15 kts to drive enhanced ascent through convergence. As this inflow continues to draw robust thermodynamics northward, regenerating cells are expected to develop across the Gulf and then repeatedly train northward and onshore. The HREF neighborhood rainfall rate probabilities for 2"/hr peak above 60% during the next few hours, suggesting the deeper cores will contain rates that may exceed 3"/hr at times. Although storms will move steadily northward, with several rounds of rainfall anticipated, this could result in 2-4" of rain with locally higher amounts possible as reflected by HREF/REFS 5"/6hr probabilities reaching 15-40%. The heaviest rainfall is expected to be along the immediate coast in the vicinity of Mobile Bay, but as the axis of elevated 850mb winds push northeast through morning, the environment could support more expansive heavy rainfall farther north into parts of southern AL as well. This suggests that while any impacts will be most likely along the immediate coast and over urban areas, any training of these intense rates, especially as instability pushes northward later this morning, could result in instances of flash flooding. Weiss ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-L8Z3naUd_aU_PnOhf_tjoUlmUbMikEjE__X7VOIyUgudZcI23OlZBoO6tphKcpJ5aE9= 7vmbHKW50YIu6jCatQXU5Zo$ for graphic product... ATTN...WFO...BMX...LIX...MOB...TAE... ATTN...RFC...ALR...ORN...NWC... LAT...LON 32218747 32128689 31788655 31188610 30758593=20 30308583 30118653 30068714 29998814 30068854=20 30148882 30858909 31258859 31628832 32008791=20 =20=20=20=20=20=20=20=20=20=20=20=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) .