Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Apr 29 2023 19:28:24 AWUS01 KWNH 291928 FFGMPD ALZ000-MSZ000-LAZ000-ARZ000-300126- Mesoscale Precipitation Discussion 0215 NWS Weather Prediction Center College Park MD 327 PM EDT Sat Apr 29 2023 Areas affected...portions of MS and adjacent areas of LA Concerning...Heavy rainfall...Flash flooding possible Valid 291926Z - 300126Z Summary...Showers and thunderstorms are beginning to grow in coverage near the low- and mid-level centers of a cyclone centered near the region. Hourly rain totals to 2" and local amounts to 4" appear possible. Discussion...A pair of surface lows are developing across portions of MS this afternoon as a multi-centered upper low/shear axis moves towards the region from in and near the ArkLaTex.=20 Precipitable water values are near 1.25", which would normally argue against broader convective heavy rain potential, but 1000-500 hPa thickness values are lowering across the region to near or below 5580 meters implying that the atmosphere is quite saturated. CIN is slowly eroding, with ML CAPE showing a broadening area of 500+ J/kg values due to a combination of some daytime heating and cooling aloft. No mid-level capping is present, based on 700 hPa temperatures near or below freezing.=20 Effective bulk shear is 25-40 kts. When combined with the nearly cyclone at the surface and aloft, this would allow for short training bands and possible mesocyclones.=20 The mesoscale guidance has some concept of what's upcoming, though it already appears slow with the band of convection shifting through MS presently. Development is expected across the ArkLaMiss (which should be slower moving) as well as portions of MS with discrete activity forming ahead of the main band. With the possibility of mesocyclones forming in the area, any forming along the existing band would help ramp up hourly and overall totals. Believe 2" an hour totals and local amounts to 4" are possible within this air mass, with both longer duration and shorter duration heavy rainfall possible within this regime.=20 While this barely eclipses flash flood guidance values, it would be more problematic in urban areas. Believe any heavy rain-related issues should be isolated to widely scattered. Roth ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6jOFNiv2fChUKF21C7Gxfr0POJVE00uYzk5qlA_SSIsnBRnQ6kiOVJZ-PWWqBpKFZuxK= Gh22TTeNxTcAEMyxRqGUjoQ$ for graphic product... ATTN...WFO...BMX...JAN...LCH...LIX...LZK...MEG...MOB...SHV... ATTN...RFC...LMRFC...SERFC...NWC... LAT...LON 34488877 32838755 30738786 29518904 29419041=20 30789160 32469217 33539140 34118995=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) .