Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Mar 31 2025 03:22:38 AWUS01 KWNH 310319 FFGMPD MSZ000-LAZ000-TXZ000-310900- Mesoscale Precipitation Discussion 0098 NWS Weather Prediction Center College Park MD 1118 PM EDT Sun Mar 30 2025 Areas affected...Eastern Texas...Western Louisiana... Concerning...Heavy rainfall...Flash flooding possible Valid 310320Z - 310900Z SUMMARY...A favorable back-building environment/slow cell propagation will give way to broader warm advection off the western Gulf resulting in expanding convective cluster into the middle overnight period. Rates of 2-2.5"/hr and spots of 3-4" totals across recently saturated grounds pose possible localized flash flooding to continue through early morning.=20 DISCUSSION...03z Surface analysis depicts a well defined front stretching from the Delta region of E AR across toward Texarkana before sagging south across central TX. A pool of enhanced low level moisture exists through the Sabine River Valley nosing toward the frontal zone with Tds in the lower 70s and some return moisture off the western Gulf supporting 1.5-1.75" total PWats.=20 Aloft, GOES-E WV suite denotes a 3H 90kt speed max tracking across OK before cyclonically curling northeast across AR/S MO; while the sub-tropical jet axis dives south across the Rio Grande and southern TX, providing a strong divergence pattern aloft. This combination of factors has resulted in a few thunderstorms near a weak surface to boundary layer low near TYR. While winds are weak, boundary layer inflow is out of the W and SW per upstream VWP noting solid inflow and ability of convection to backbuild over the last hour or so. This is noted well in the cycling overshooting tops in 10.3um EIR as well, limiting forward propagation of the heavy rainfall cores. While dry/cooler air aloft is supporting hail generation, there is ample moisture flux to support 2"/hr rates; and localized spots of 2-4" are already starting to be estimated. While not particularly confident due to edge of the convective domain, recent WoFS solutions suggest back-building cells may even be capable of 4-6" totals per 50th to 90th percentile totals.=20 The favorable divergence should be slackening over the next 3-5hrs to reduce this potential back-building. However, this will come with the diurnal increase in southwesterly flow off the western Gulf with increased warm-advection after 06-07z. Combined with eastward approach of stronger shortwave/general height-falls, convective over-turning is expected further south and east.=20 Moisture flux convergence into the cells will be prolific with Pwats nearing 2.0" and confluent 25-30kt 850mb flow will support 2-2.5"/hr rates. Slow forward propagation is expected allowing for spot totals of 3-4". Overall, the area has been quite saturated with 0-40cm percentiles over 85% per NASA SPoRT and saturation ratios of 65-80% across the area of concern/convective development. As such, spots of flash flooding are likewise considered possible through early morning across W and SW LA. Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-SSsD5Z2tjugsUFtSK5xsbjr_lzPqsj0NIZfzcvpF53G9M7ZfEaTLZDve8eAHjDms3-R= wcIumUPH1UlCt6Z7NUBvZ14$ for graphic product... ATTN...WFO...HGX...JAN...LCH...LIX...SHV... ATTN...RFC...LMRFC...WGRFC...NWC... LAT...LON 32589312 32329195 31969154 31139137 30189160=20 29679216 29799335 29749454 30029489 31019526=20 31989506 32529448=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) .