Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Dec 02 2025 00:36:34 AWUS01 KWNH 020035 FFGMPD FLZ000-ALZ000-MSZ000-LAZ000-020634- Mesoscale Precipitation Discussion 1256 NWS Weather Prediction Center College Park MD 734 PM EST Mon Dec 01 2025 Areas affected...portions of the central Gulf Coast Concerning...Heavy rainfall...Flash flooding possible Valid 020034Z - 020634Z Summary...A combination of cell training and backbuilding should continue to lead to hourly rain amounts to 1.75" with local totals to 4", which could cause flash flooding in urban areas. Discussion...Instability across portions of the central Gulf Coast continues to rise ahead of a negatively-tilted shortwave across OK. Precipitable water values are ~1.6" per GPS data and MU CAPE values of 500+ J/kg lie across the southeast tip of LA and continue shifting north towards the MS/AL barrier islands. Radar estimates from LIX/Hammond LA indicate that hourly amounts peaked near 1.75" not far from the eastern suburbs of New Orleans recently, with local totals above 2.5" so far. Occasional hourly rain amounts to 1.5" have been seen in backbuilding convection in southernmost AL. Effective bulk shear of 25-45 kts lurks across the area which is helping to form a band within an area of 850 hPa confluence. The band is showing some signs of shifting northward across southern AL and slightly eastward in southeast LA. Additional activity south of the LA/MS coasts within a convergence zone which extends from northwest Cuba towards the central Gulf Coast could advect northward towards portions of this area in the next several hours and cause additional issues. The guidance has not been ideal in this region thus far -- too far north and too light -- though the 18z hi-res NAM appears to have the best idea, so used it as a starting point for the MPD bounds, making some adjustments based on radar reflectivity trends. The region has been dry, so flash flood guidance values are high. Hourly amounts to 1.75" and local totals to 4" appear possible where cells train and/or backbuild, which would be most problematic in urban areas. Roth ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6SdogcIUxTtroqQTUwxSALeN9Fo_uMvC5I4pW6eAAjX9DWw67VnyMfB31nkTA5_xaSPt= yY_XxORQJb-wb9BRCh179PU$ for graphic product... ATTN...WFO...BMX...LIX...MOB...TAE... ATTN...RFC...ALR...ORN...NWC... LAT...LON 31928616 31298582 30558670 30248743 30078846=20 29938870 29778905 29439024 29689078 30768934=20 31778728=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) .