Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri May 12 2023 22:36:05 AWUS01 KWNH 122236 FFGMPD TXZ000-130434- Mesoscale Precipitation Discussion 0277 NWS Weather Prediction Center College Park MD 635 PM EDT Fri May 12 2023 Areas affected...southwest/south/west-central Texas and the Rio Grande Valley Concerning...Heavy rainfall...Flash flooding likely Valid 122234Z - 130434Z Summary...Convective coverage will increase through the evening hours with slow storm motions and potentially intense rain rates expected. Flash flooding is likely between 00Z-04Z. Discussion...A couple areas of very heavy rainfall are occurring and should continue in the near term. One area - located across the Transpecos near/southwest of Fort Stockton. Strong instability and ascent beneath a mid/upper shortwave trough was allowing for deep convection to continue, while weak steering flow aloft and broadening cold pools were allowing for slow/erratic storm motions. FFGs vary widely in that area (ranging from 1.5-4 inch/hr thresholds), and although rain rates exceeding 2 inches/hr are occurring in spots, any opportunity for excessive rainfall and runoff may be limited and/or tied to sensitive/low-lying areas.=20 The longevity of this cluster is a bit uncertain - the consistent overturning ongoing across the region should stabilize the low-levels and eventually decrease the heavy rain threat over the next 2-3 hours and especially after sunset. The flash flood threat continues through at least 01Z in the region, but should remain relatively isolated in the near term. A second area of somewhat greater concern is with deep, slow-moving convection extending from San Angelo through Del Rio southward to Coahuila Province in Mexico. Again, mid-level forcing has allowed for numerous storms to form in an very unstable, moist environment (1.5-1.9 inch PW and 2500-4000 J/kg MLCAPE). Storm motions are slow and erratic in this region also, although gradual upscale growth of storms in Coahuila and increasing low-level flow somewhat orthogonal to propagation across the region should result in a larger-scale flash flood threat later tonight. The potential for 2-3 inch/hr rainfall rates exists with later-day and evening activity, which should exceed local FFGs and cause excessive runoff. This threat should begin to materialize in earnest once storms in Coahuila cross the Rio Grande over the next 1-2 hours and persist perhaps beyond the ~0430Z scheduled expiration of this current MPD. Cook ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!7pZ9ygiM635pvh7vQYbrFo-DagusdNEWVU84vAvoBACW1nzBlHYqL-LKYZW1vwIi6w9U= Zmzet6aOiYeXNg6PgPsfXyA$ for graphic product... ATTN...WFO...BRO...CRP...EWX...FWD...MAF...SJT... ATTN...RFC...WGRFC...NWC... LAT...LON 32689958 32419872 30889847 28219853 27049881=20 27079942 27890020 29240130 29410232 28940296=20 28910351 29320391 29510387 30090406 31010354=20 31710301 32060156 32240065 32420021=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 3.14-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .