Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Apr 23 2025 23:56:01 AWUS01 KWNH 232355 FFGMPD MSZ000-LAZ000-ARZ000-240454- Mesoscale Precipitation Discussion 0166 NWS Weather Prediction Center College Park MD 755 PM EDT Wed Apr 23 2025 Areas affected...in and near portions of western & northern MS Concerning...Heavy rainfall...Flash flooding possible Valid 232354Z - 240454Z Summary...Thunderstorms with some level of organization should persist in and near portions of western and northern MS in the short term. Hourly rain amounts up to 2.5" with local amounts to 5" are possible until thunderstorms fade this evening/tonight. Discussion...The mesoscale pattern in and near MS is chaotic, with a grand boundary collision coming shortly as the outflow boundaries from the cold pools near the LA/AR border, southwest TN, and eastern MS meet near the lower portion of the MS River Valley. Upstream, a strong shortwave is moving by the ArkLaTex, eastward into the region enhancing upper level divergence.=20 Precipitable water values are 1.25-1.5". ML CAPE is 1000-2000 J/kg, but CIN has set in near the LA/AR border and the central MS/AL border where temperatures have fallen below 70F. Effective bulk shear is around 25 kts, allowing some storms to attain some level of organization, but there are a lot of cell mergers apparent in recent radar imagery. Recent hourly rain amounts have been up to 2.5" in several spots near the MS/LA border as well as near Tchula MS. While there are some location differences between the 18z HREF and 12z RRFS probabilities of 0.5"+ of rain in an hour, they point to the region of highest instability between the various outflow boundaries. After 00z, there should be a slow waning in coverage of the heavy rainfall, due to both increasing CIN and decreasing ML CAPE in and near western and northern MS after all the outflow boundaries collide and the atmosphere stabilizes. Until then, hourly rain amounts to 2.5" with local totals to 5" remain possible, which could exceed flash flood guidance values and be most problematic in urban areas. Roth=20 ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!77SPtgatE5YpErfP9df76jPRGvSCGpLK5E782E-SN-PU1J1HGztd_NvgbyTuVl_itvlf= OJA8XCyMIVejpfdL-nzLGa0$ for graphic product... ATTN...WFO...JAN...LCH...LIX...MEG...SHV... ATTN...RFC...LMRFC...NWC... LAT...LON 34578912 33718927 33168965 32479048 31869051=20 30869034 30469124 31049186 31679261 32299220=20 33079141 33509102=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) .