Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Mar 02 2023 02:30:42 AWUS01 KWNH 020230 FFGMPD NCZ000-GAZ000-TNZ000-ALZ000-MSZ000-ARZ000-020830- Mesoscale Precipitation Discussion 0081 NWS Weather Prediction Center College Park MD 930 PM EST Wed Mar 01 2023 Areas affected...Portions of the Lower MS Valley and Mid-South Concerning...Heavy rainfall...Flash flooding likely Valid 020230Z - 020830Z SUMMARY...Repeating rounds of heavy showers and thunderstorms are expected heading into the overnight hours across portions of the Lower MS Valley and Mid-South. Some areas of flash flooding are expected. DISCUSSION...The latest GOES-E IR satellite imagery shows an expanding area of cold-topped convection as heavy showers and thunderstorms continue to develop and grow upscale along an axis from central/eastern AR eastward across northern MS, northern AL and much of southwest to south-central TN. The convective evolution this evening continues to be the result of strengthening moisture convergence and instability transport along and ahead of a slow-moving frontal zone dropping gradually southeast toward the Lower MS Valley and Mid-South. The latest RAP analysis shows a rather expansive area of moderate instability with MLCAPE value of 1000 to 1500+ J/kg, and with a low-level jet tending to increase with time that is currently on the order of 30 to 40 kts. PWs across the region are gradually rising and based on 00Z RAOB and GPS data are currently around 1.4 to 1.6 inches. Convection has been gaining substantial organization over the last few hours and radar imagery depicts plenty of multicell and supercell structures, and occasional instances of cell-mergers all working in tandem to produce heavy rainfall rates in addition to a range of severe weather hazards. Some rainfall rates based on MRMS with the stronger cells have been up into the 1.5 to 2 inch/hour range. Given the pooling of favorable thermodynamics and rather robust vertical shear profiles, much of the convection should remain well organized and sustainable for a significant part of the overnight period. Facilitating this will be the arrival of strengthening upper-jet support/forcing aloft downstream of a positively tilted upper trough and closed low over the Southwest. There is a rather strong consensus in the latest hires CAM guidance for some swaths of 2 to 4 inch rainfall amounts overnight. This will be driven by a likelihood of repeating rounds of convection given the orientation of cells becoming nearly parallel to the deeper layer steering flow. There may be a few spotty locations that reach or exceed 5 inches, and especially over northern MS and northern AL where the thermodynamics are a bit stronger. The soil conditions across the region are already locally quite moist given the rainfall over the last few hours, and the additional rains overnight will tend to favor at least some areas of flash flooding. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!74KSueJwAm_5s-dh4YNNm-DDaGSyeLbI1WQ9JwgI30VkZEmn0XhUwq0NQkJenhbOWgjU= fUeX_MMwpshs41a5RRFtZ9Y$ for graphic product... ATTN...WFO...BMX...FFC...GSP...HUN...JAN...LZK...MEG...MRX... OHX... ATTN...RFC...ABRFC...LMRFC...OHRFC...SERFC...NWC... LAT...LON 36298404 35998341 35238368 34598508 34118659=20 33718900 33599141 33759274 34259302 34849239=20 35309048 35558854 35738703 35918581=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) .