Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Nov 26 2025 04:17:58 AWUS01 KWNH 260417 FFGMPD TXZ000-260920- Mesoscale Precipitation Discussion 1251 NWS Weather Prediction Center College Park MD 1117 PM EST Tue Nov 25 2025 Areas affected...South Texas Concerning...Heavy rainfall...Flash flooding possible Valid 260415Z - 260920Z Summary...A localized flash flood risk will exist across portions of southern TX through at least 09Z. Slow moving and/or backbuilding of thunderstorms could result in isolated totals in excess of 3-5 inches, though some uncertainty in placement and timing remain. Discussion...04Z radar and infrared satellite imagery showed a lone thunderstorm over southern Webb County, about 15 miles east of the Rio Grande with a slow northward drift. Radar and satellite imagery also showed recent attempts at development over Live Oak County and portions of northern Mexico though low level CIN may be hindering further development. MRMS-derived hourly rainfall was over 2 inches with the cell although the likely presence of large hail may be over-inflating those values and no ground truth was available to confirm actual rain rates. The cell was located near a quasi-stationary front which has drifted north and west over the past couple of hours due to a weak low level easterly surge off of the warm Gulf waters with surface dewpoints in the lower 70s from CRP to BKS and southward to the Rio Grande. Low level convergence and lift augmented by a subtle shortwave impulse tracking east from north-central Mexico as seen in 6.2 micron imagery seem to be triggers for the storm(s). 00Z soundings from CRP and BRO showed 1.3 to 1.6 inch PW values along with 1500-2000 J/kg MLCAPE, with this airmass likely in place near the cell over Webb County. The environment was supportive of a mixture of storm modes with sufficient shear for organized cells and straight-line hodographs which could support splitting storms. Bunkers right motion was toward the SSE near 20 kt, Bunkers left from the SSW near 15 kt and deeper layer mean winds from the west between 5 and 20 kt. While recent hires model guidance shows a decent signal for localized heavy rain in the vicinity of southern TX, there is poor agreement in placement and timing. Current thinking is for the existing cell over Webb County to maintain for at least another 1-2 hours with a continued drift toward the north or west with localized heavy rain. The future beyond that time is unclear as better low level confluence shifts westward into Mexico but additional convective development appears possible near the frontal boundary and south TX coast later in the night. Additional potential for high rates in excess of 2 in/hr and spotty totals in excess of 3 to 5 inches will remain possible. Otto ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-otaUnJHL9uHMhHKbJWde9LUbFGUwUeanvAO9Vad5_uIr0z-QeNKrL-6eTtn8HcWvIKY= zxOkhDsM0PZ1MCtcwAVzSW4$ for graphic product... ATTN...WFO...BRO...CRP...EWX... ATTN...RFC...FWR...NWC... LAT...LON 28739716 28419661 27979657 27069704 25679698=20 25829839 26089916 26689958 27359974 27970016=20 28239969 28689774=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) .