Flash Flood Guidance
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Issued by NWS
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451 AWUS01 KWNH 100358 FFGMPD MSZ000-LAZ000-TXZ000-100700- Mesoscale Precipitation Discussion 0255 NWS Weather Prediction Center College Park MD 1157 PM EDT Thu May 09 2024 Areas affected...southeastern TX into south-central LA Concerning...Heavy rainfall...Flash flooding possible Valid 100353Z - 100700Z SUMMARY...Flash flooding will be possible across southeastern TX into south-central LA as a cluster of thunderstorms organizes. However, there is potential for increasing forward propagation through 07Z which would limit flash flood concerns. DISCUSSION...Radar imagery at 0345Z showed that a cluster of thunderstorms over the Piney Woods region of southeastern TX has begun to increase in forward speed toward the southeast over the 60-90 minutes. Two discrete supercells farther west, between Houston and San Antonio on either side of I-10, were tracking southeastward as well, with the lead cell (south of I-10) largely dissipated as it moved farther south into a more capped environment...as represented on the 00Z CRP sounding. The western cell(s) does not appear to pose a flash flood threat and is expected to follow a similar weakening trend as the one south of I-10 in the short term, with continued southward extent. Farther east, there are indications that the cluster of cells over southeastern TX will continue to track east or east-southeast within a weakly capped environment (per 03Z SPC mesoanalysis), following Corfidi vector approximations, but modifying for the stronger 850 mb winds observed at the KLCH VAD wind than RAP estimates which were about 10 kt weaker. HRRR forecasts are mixed if the cluster over southeastern TX weakens in the short term or maintains a similar intensity as it encounters a better low level moisture feed into LA. Either way, it appears at least a limited flash flood threat will exist with potential for peak/isolated 2-3 inch rain totals within short term training, possibly augmented by convection over central LA, dropping south. Due to elevated soil moisture values from recent heavy rainfall, sensitivity to flash flooding appears to be higher than average, but overall forward propagation is expected to limit the flash flood threat, especially with potential for increasing forward speed through 07Z. Otto ...Please see www.wpc.ncep.noaa.gov for graphic product... ATTN...WFO...HGX...JAN...LCH...LIX...SHV... ATTN...RFC...LMRFC...WGRFC...NWC... LAT...LON 31649281 31549153 31469015 30719016 30109072 29939164 29849350 29899474 30239520 30659525 30999488