Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu May 11 2023 21:40:44 AWUS01 KWNH 112140 FFGMPD ALZ000-MSZ000-LAZ000-120339- Mesoscale Precipitation Discussion 0266 NWS Weather Prediction Center College Park MD 540 PM EDT Thu May 11 2023 Areas affected...southern Mississippi, portions of southeastern Louisiana Concerning...Heavy rainfall...Flash flooding possible Valid 112139Z - 120339Z Summary...Slow-moving downpours and multiple cell mergers could result in a localized flash flood risk through at least 02Z or so. Discussion...A mature MCS has picked up forward speed across central/northeastern Mississippi this afternoon, and should reach the MS/AL border region over the next hour. Several bowing/LEWP segments were noted with the MCS across northern Mississippi as well. The southwestern flank of the complex, however, has slowed in forward speed while encountering a very moist, strongly buoyant airmass (characterized by 1.8 inch PW values and 3000+ J/kg MLCAPE). The instability and continued convergence along a local gust front near the leading edge of the MCS has led to renewed, deep convective development. Furthermore, wind fields aloft are quite weak (less than 20 knots) especially across the southern half of Mississippi. Slow-moving storms and multiple cell mergers are resulting in an uptick in rainfall rates across the region - locally exceeding 2 inches/hr at times. The rain rates are falling on ground conditions that are somewhat moist from recent rainfall over the past week. FFGs are fairly high (around 2.5-4 inches/hr, peaking across southeastern Mississippi). The heavier rain rates should result in localized flash flood potential as FFG thresholds are expected to be exceeded only in a few spots. Over time, CAMs suggest that the MCS should pick up forward speed to the southeast, which appears to be plausible as cold pools mature due to the abundant deep convection focused near the outflow boundary. This process will likely be driven by convective evolution as opposed to any forcing associated with greater MCS organization located north of the MPD area. The localized flash flood risk should persist through at least 02Z or so. Cook ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-60Kt5GNxy5B_t59H9ETyUr2StzDGGtw_Mn1vzoWFEcEM35V4tjwi2WHVhFPf4kt3Y51= 9OrbsKI_vEd1rSWxq4h0QeU$ for graphic product... ATTN...WFO...BMX...JAN...LCH...LIX...MOB...SHV... ATTN...RFC...LMRFC...SERFC...NWC... LAT...LON 32698875 32388841 31488842 30958848 30488843=20 29898976 29759090 30009213 30469303 31279249=20 31639209 32399213 32539173 32229128 32119064=20 32338996 32598949=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) .