Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Apr 22 2025 00:11:58 AWUS01 KWNH 220011 FFGMPD ALZ000-MSZ000-LAZ000-220530- Mesoscale Precipitation Discussion 0156 NWS Weather Prediction Center College Park MD 810 PM EDT Mon Apr 21 2025 Areas affected...northeastern LA into central MS/AL Concerning...Heavy rainfall...Flash flooding possible Valid 220009Z - 220530Z SUMMARY...Isolated flash flooding will be possible over the next 3-5 hours from northeastern LA into central MS and central AL. Potential will exist for training and rainfall rates of 2-3 in/hr with totals up to 5 inches, although coverage of these higher rainfall totals should be quite limited if they do occur. DISCUSSION...Scattered to numerous thunderstorms were ongoing from the central LA/MS border into central MS and western AL at 00Z, near and south of a quasi-stationary front. SPC mesoanalysis data from 23Z showed MLCAPE across the region was 1000-1500 J/kg with 1.5 to 1.8 inches of precipitable water. Water vapor imagery showed a shortwave over northern LA, beginning to advance northeastward into MS, and recent cooling of cloud tops near Natchez, MS may be a result of ascent ahead of the advancing shortwave. Farther east, existing convection along the MS/AL border has produced a rain-cooled boundary within the warm sector of the stationary front and subtle enhancement of 925-850 mb winds ahead of the shortwave are forecast through 03Z which should support increased overrunning of the front and rain-cooled outflow boundary. Per radar imagery, mean storm motions were off toward the northeast at 10 to 20 kt (locally higher), quasi-parallel to initiating boundaries which could promote some training and brief backbuilding of storms over the next few hours. Favorably diffluent flow aloft was, and will continue to be, in place within the broad left-exit region of a jet max positioned over south-central TX, which should aid with lift across the lower MS Valley and just downstream. While the environment is moist, diurnal cooling and convective overturning will contribute to some loss in instability overnight, which means coverage of convection may be near its max at the present time across the broader LA/MS?AL region. Nonetheless, some flash flood threat will continue into the first half of the overnight with rates of 2-3 in/hr easily attainable within the favorable environment with potential for additional development. However, limited coverage of these higher rates and generally high flash flood guidance for the region should limit the areal extent of any flash flooding that might develop. Otto ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-2JeLoNx706_syp8m3NMuRmrtoFgkj1r70crNPp-wAC4r7VpCeruDXQi5Cy68u-7Gj4G= 71LaZa1oTNAnsR-m16lWLkA$ for graphic product... ATTN...WFO...BMX...HUN...JAN...LCH...LIX...MEG...MOB...SHV... ATTN...RFC...LMRFC...SERFC...NWC... LAT...LON 34028735 33748629 32798640 31858799 31458898=20 30729009 30769152 31229190 31999192 32839120=20 33508968=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 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .