Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Apr 23 2023 05:37:24 AWUS01 KWNH 230537 FFGMPD TXZ000-231035- Mesoscale Precipitation Discussion 0204 NWS Weather Prediction Center College Park MD 136 AM EDT Sun Apr 23 2023 Areas affected...portions of south-central TX Concerning...Heavy rainfall...Flash flooding possible Valid 230535Z - 231035Z Summary...Development and expansion of thunderstorms is expected across the Middle Rio Grande Valley over the next few hours. While timing of specific evolution remains uncertain, slow moving and repeating of cells are expected to produce flash flooding with rainfall rates as high as 2+ in/hr. Discussion...05Z surface observations and infrared imagery helped place a southward sinking cold front from eastern TX into southern portions of the Edwards Plateau and westward into northern Chihuahua. Instability and moisture across the Middle Rio Grande was estimated to be more than sufficient to support heavy rain with the 05Z SPC mesoanalysis showing 1.0-1.3 inch PWATs and 1000-2500 J/kg MLCAPE but with weak CIN in place. The 00Z DRT showed a small capping inversion between 850 and 800 mb that will not be be overcome until the cold front to the north passes through and/or higher moisture in the 850-700 mb layer moves into the region. However, early development of convection appears to be occurring just north of Uvalde in local radar imagery. Steep 700-500 mb lapse rates of 8.2 C/km were also noted on the 00Z DRT sounding which should support some degree of elevated instability/convection after the cold front passes by at the surface. Layered PW imagery has shown an increase in the 850-700 mb layer moisture occurring from both southerly transport up the Rio Grande and in the wake of the cold front to the north. Expectations are for thunderstorms to increase along and just ahead of the southward moving cold front near or just east of the Rio Grande within the over 1-3 hours, with cell movement toward the east or southeast at 15-20 kt. However, moist low level southerly flow is expected to support the regeneration and expansion of convection upstream with repeating and slow overall system movement. Over time, With mean cell motion toward the east/southeast and low level inflow from the SSE at 20-30 kt, eventual clustering of cells may allow for movement of heavy rain toward the middle to lower TX Coast later this morning. Prior to that southeastward propagation occurring, rainfall rates of 1-2, locally 2+ in/hr are expected with 6-hr rainfall totals of 2-4 inches through 10 or 11Z. While the bulk of the expected rainfall in the near term should be west of where heavy rain fell over the past 72 hours, localized flash flooding may still result. Otto ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!5H5tAYvlCM21p6XmOP9fMPSLnsgdLqNo-CLXbvBKgZe6YMEf_WaRWPGSDsw0nhGIAvFV= -rbWuI0lcACHibUCbW-LLdM$ for graphic product... ATTN...WFO...CRP...EWX... ATTN...RFC...WGRFC...NWC... LAT...LON 30159989 30099924 29869881 29479858 28999861=20 28519902 28369963 28520034 29150100 29490152=20 29920159 30050120 30110043=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) .