Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed May 21 2025 15:22:11 AWUS01 KWNH 211522 FFGMPD LAZ000-TXZ000-212030- Mesoscale Precipitation Discussion 0301 NWS Weather Prediction Center College Park MD 1121 AM EDT Wed May 21 2025 Areas affected...Southern Louisiana...Far Upper Texas Coast... Concerning...Heavy rainfall...Flash flooding possible Valid 211520Z - 212030Z SUMMARY...Highly efficient, slow moving thunderstorms with additional training and upstream development may result in localized 2-3"/hr rates and rapid inundation flooding is possible. DISCUSSION...An extremely moist deep layer profile exists along the frontal zone that is becoming coincident with the LA/Upper TX coastline. Total PWat values are over 2.25" with some suggestion of 2.5" values embedded along it. Initial convection has further sharpened the insentropic slope with 10-15kts of northeasterly flow opposed by 5-10 kts of due southerly flow across the front.=20 Upper-level broad right entrance to 90kt 3H jet across east-central TX into northern LA is providing solid upper level divergence, which the convection is likely further enhancing to support additional development/organization over the next few hours. Given moisture, rates of 2.5-3"/hr are likely with the cores of the cells, which can be confirmed by last hour at LFT as well as surrounding observations near UofL-Layfette of 3" in the last hour as well...supporting localized rapid inundation potential.=20=20 While the gradient of deep layer moisture/unstable environment basically aligns from I-10 to the coast, the steering flow is ideally orientened parallel to the front and moisture/instability graident to allow for favorable training environment. So given broad southerly flow/isentropic ascent convergence there are additional cells in the Upper TX coastal region with further congested cu west of Galveston Bay, hinting at continued expansion potential along/upstream for localized training environment throughout the rest of the morning/early afternoon hours from south of Houston to New Orleans. While Hi-Res CAMs suggest some dry air mixing to allow for southward propagation (cold pool generation), RADAR trends have not be aligned with this evolution but the risk should still remain along/south of I-10. Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_fFy51LkxMH3PmueKRUzcGNlutVOHm1mK6VQpk4JFI_ChbbdzkV6n6Y67jaLck7vBZt5= -QQ6w2SOE43OhKcPQG9f8xk$ for graphic product... ATTN...WFO...HGX...LCH...LIX... ATTN...RFC...FWR...ORN...NWC... LAT...LON 30649023 30058986 29649004 29479139 29499251=20 29629299 29699347 29059539 29529554 30169398=20 30349339 30629173=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) .