Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Jul 01 2025 17:49:37 AWUS01 KWNH 011749 FFGMPD TXZ000-012250- Mesoscale Precipitation Discussion 0568 NWS Weather Prediction Center College Park MD 148 PM EDT Tue Jul 01 2025 Areas affected...South Texas Concerning...Heavy rainfall...Flash flooding possible Valid 011750Z - 012250Z SUMMARY...Scattered showers and thunderstorms moving north-northwestward into South Texas are capable of producing isolated instances of flash flooding and 2-3"/hr rates through at least early this evening. DISCUSSION...Latest radar and satellite imagery depicts north-south bands of tropical downpours streaming north-northwest into South Texas from the northern Gulf Coast of Mexico. These thunderstorms are occurring on the northwest periphery of a mid-level low churning over north-central Barry (can be tracked to the remnants of former T.S. Barry). Maximum estimated hourly rainfall rates from MRMS are around 2-2.5" over the last hour or so, with 1.55" recorded at the Brownsville International Airport over the last 3 hours. While this initial band appears to hang up along the coast, a separate one approaching from far northeast Mexico may provide greater coverage of heavy rainfall this afternoon based on recent radar scans and strong southerly 850-700 flow around 20-25 kts. This is allowing PWs to remain well above what's necessary for intense rainfall rates as values climb to near 2.5" (over the 95th climatological percentile per the 00z ECENS). Additionally MLCAPE values of 1000 J/kg remain just inland from the Gulf as 2000 J/kg linger in the inflow region over the far western Gulf. Even though storm motions may be fast and on a north-northwesterly direction, upwind propagation vectors are weak and may lead to backbuilding towards the higher instability over the western Gulf. This supports an environment for additional heavy rainfall that may compound to lead to isolated flash flooding concerns over a region with relatively high FFG. 3-hr FFG in far South Texas remains around 3", locally lower along the Rio Grande Valley. Even though CAMs are highly uncertain regarding the northward extent of heaviest thunderstorms, 12z HREF probs of at least 3" in 6-hrs (ending 21z) are around 30% for the southern Rio Grande Valley region of South Texas. This again when combined with current radar/satellite supports the potential for localized instances of flash flooding. Snell ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!517jVvMtSJcexGf_MNgLKbNenlxCfNRbdBslmsMOBOK1eF02mpGkx0auV3T8X_6pJ7l2= Jx3Q7OOtI07xuAd0JywvaTs$ for graphic product... ATTN...WFO...BRO...CRP... ATTN...RFC...FWR...NWC... LAT...LON 27889929 27799841 27129731 26369696 25819719=20 25769779 26179878 26749953 27449971=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) .