Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Aug 31 2024 06:28:39 AWUS01 KWNH 310628 FFGMPD LAZ000-TXZ000-311230- Mesoscale Precipitation Discussion 0954 NWS Weather Prediction Center College Park MD 227 AM EDT Sat Aug 31 2024 Areas affected...Coastal Southeast Texas...Southwest Louisiana... Concerning...Heavy rainfall...Flash flooding possible Valid 310630Z - 311230Z SUMMARY...Slow moving/back-building highly efficient bands of thunderstorms of 2.5"/hr rates and localized totals up to 5"+ pose possible flash flooding through remainder of overnight period. DISCUSSION...GOES-E 3.9um SWIR and surface observations depict an either narrowly closed or elongated surface trough southwest of Galveston hugging the coast with a tight northeast constricted flow field resulting in enhanced directional convergence enhanced by coastal frictional convergence from Galvestion Bay eastward toward Sabine Pass. RAP analysis and streamline flow in SWIR denote a core of confluent boundary layer flow of 15-20kts within a band directed toward Sabine Pass and far SW LA at this time; unsurprisingly, total PWats are maximized in the band over 2.5" resulting in very strong moisture flux convergence. Very warm/moist Gulf is nearing diurnal peak of low-level heat release likely to further destabilize the lower environment with 2000 J/kg of CAPE analyzed within a very saturated moisture profile. This will support very efficient tropical rainfall rates in the coming hours.=20 Aloft, GOES-WV shows a very symmetric TUTT cell centered along the SW LA coast in eastern Vermilion Parish with well defined outflow channel of 25-30kts supporting modest divergence in the region to support any thunderstorms, providing the upper-level support for convective longevity. So given strength of convergence and ample vertical development, rates of 2.5-3"/hr are probable as HREF 2"/hr reach 60-70% and 3"/hr up to 30% between 09-12z. While convergence is currently strong along/northward into SE TX, inflow will support offshore/back-building propagation vectors that have a solid potential of limiting duration over land, resulting in greatest rainfall potential to be offshore once again this morning. However, given placement of the surface wave, there remains solid potential for 3-6" rainfall totals by 12z in Chambers/Jefferson TX counties and Cameron parish in LA. While the region has sandier soils, rates of 2.5-3"/hr for even 1-2 hours may result in rapid inundation flooding but given uncertainty in placement over land, flash flooding is considered possible at this time. Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!5FmagwiAN8sho_aByFJQHOg3os9dqSpE5X5H73TeiUOWrZnz1Rqi8N-HLbKkKmRoPLcV= IzdjTQ56tsmRVcyGWEvwO14$ for graphic product... ATTN...WFO...HGX...LCH... ATTN...RFC...LMRFC...WGRFC...NWC... LAT...LON 30359404 30319370 30189340 29689288 29699351=20 29599407 29299468 29229493 29519495 29759494=20 30029491 30269459=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) .