Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun May 07 2023 14:51:53 AWUS01 KWNH 071451 FFGMPD TXZ000-071749- Mesoscale Precipitation Discussion 0231 NWS Weather Prediction Center College Park MD 1050 AM EDT Sun May 07 2023 Areas affected...portions of central/south Texas Concerning...Heavy rainfall...Flash flooding possible Valid 071449Z - 071749Z Summary...A cluster of slow-moving thunderstorms has produced 1-2 inch/hr rain rates while moving slowly east-northeastward across the discussion area. These trends are expected to continue for at least a couple more hours. A Marginal risk upgrade is being considered for the 16Z Day 1 ERO Update. Discussion...Showers and thunderstorms have persisted along a general axis from near Eagle Pass/FTN east-northeastward to near Victoria/VTC this morning. Convective coverage within this axis is exceeding model guidance so far this morning, and is likely tied to ascent aloft from weak/subtle shortwave troughs near the region and very steep (~8C/km) mid-level lapse rates associated with a stout elevated mixed layer across the region.=20 Additionally, surface dewpoints in the upper 70s F were supporting MLCAPE values exceeding 3000 J/kg across the region that will continue to support strong updrafts as long as cells are able to root in the boundary layer. Recent convective evolution suggests that this potential is being realized along the convective axis and may continue to do so as cold pools mature and 30-40 kt southerly low-level flow (at 850mb) continues to provide sustained convergence for renewed updrafts. The convective evolution this morning is a bit uncertain. In the short term, storms along the heavy rainfall axis are orienting parallel to steering flow aloft to allow for areas of 2-2.5 inch/hr rain rates to begin just southeast of San Antonio.=20 Concern exists that these rates could persist for another couple hours at least and gradually increase flash flood concerns. Over time, however, weakening low-level flow may act to weaken low-level convergence. Furthermore, the lead impulse that initiated this morning's convection is gradually shifting northeastward, and while upstream impulses are evident in objective analyses, it is unclear whether sustained updraft development will continue to the extent that is happening currently. Recent CAMs suggest some potential for persistence of convection through 20Z, although overall model performance in depicting the convective activity has been poor. Given the ongoing scenario (including at least a brief period for potential training of convection), a Marginal Risk area is being considered for the Day 1 ERO Update scheduled for 16Z. The convective evolution will also be re-evaluated for another possible MPD after around 17Z or so. Cook ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!4r9Q3zzpl0rzQuL9NTQpGEPs54DXOt4rXObf8RrgVdBo1eiCvmh8Rl48LzawL3HKt2O0= WiCI9EbdXqKjmfyP6pjy_Hw$ for graphic product... ATTN...WFO...CRP...EWX...HGX... ATTN...RFC...WGRFC...NWC... LAT...LON 30669567 30189485 29529489 28999553 28049757=20 27959878 28819928 29599897 30069820 30449691=20 =20=20=20=20=20=20=20=20=20=20=20=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) .