Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Apr 23 2023 15:23:34 AWUS01 KWNH 231523 FFGMPD TXZ000-232130- Mesoscale Precipitation Discussion 0206 NWS Weather Prediction Center College Park MD 1123 AM EDT Sun Apr 23 2023 Areas affected...Southern Texas... Concerning...Heavy rainfall...Flash flooding possible Valid 231530Z - 232130Z SUMMARY...Fast forward propagating thunderstorms with very intense short-term rainfall totals (1.5-2"/15min) pose potential for scattered incidents of possible localized flash flooding before moving offshore through late-afternoon. DISCUSSION...GOES-E EIR depicts a mature MCS across South Texas with new main nodes of stronger activity. An intense broad rotating cell along the Rio Grande River feeding off enhanced southeasterly sfc inflow with higher theta-E air pooled along the valley floor and a broader area of isentropic ascent along and ahead of the weak MCV near Live Oak county, slowly dropping southeast. Both areas are feeding off high unstable air with continued strong inflow responding to favorable mid to upper level right entrance evactuation that dominates central to south Texas (60-70kt 3H jet). As such, sfc flow of 15-20kts and 850mb 25-30kt flow strongly converges and ascends along the southward sagging cold front with localized flow strenghtening/accelerating in response to the MCV or Meso-low of the super-cell. The flow has ample surface to 700 moisture providing the bulk of the moisture flux over 1.75" Total PWat, steadily increasing to near 2" over th next few hours. This will continue highly efficient rainfall production with HRRR estimates of 1.5-2/15 minute totals which has been supported by RADAR/local observations, particularly lon the Rio Grande.=20 Limiting factors will be cool pool generation (particularly for the Rio Grande supercell), as well as stronger forward propagation due to the southeasterly strong inflow resulting in limited local duration of the intense rates. The area of isentropic ascent across the northern Lower TX coastal plain into the central Texas coast will be less intense due to the broader ascent, but could have some increased duration but the rainfall totals of 3-4" may still be about the same for the event. At the interface of the cold front nearest the MCV, this may result in the most extreme rainfall totals perhaps locally up to 5" as suggested by recent HRRR solutions and 12z ARW2 (and axis of Nam-Nest to counteract its know high bias). This would be over the area of highest FFG, given sandier soil conditions, but the sheer rate may still result in less infiltration and higher run-off resulting in localized flash flooding conditions and remains considered possible through the late afternoon/evening hours as the MCS migrates offshore.=20 Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6GU3VqZi2IW52PzbM0tI-irZTv_THUXraEI7VIh1mqOM2j0SHAUUFIUnLh2-grF2e2_f= A_YFgSxxOZUYT9budVjpa8E$ for graphic product... ATTN...WFO...BRO...CRP... ATTN...RFC...WGRFC...NWC... LAT...LON 28439704 28399660 28279645 27959690 27229727=20 26529717 26129703 25889721 25849765 26109857=20 26329909 26789940 27279966 27609979 27829956=20 28019899 28279816=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) .