Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Feb 16 2023 17:28:57 AWUS01 KWNH 161728 FFGMPD ALZ000-MSZ000-LAZ000-162327- Mesoscale Precipitation Discussion 0068 NWS Weather Prediction Center College Park MD 1228 PM EST Thu Feb 16 2023 Areas affected...Portions of Central and Eastern LA...Southwest to East-Central MS...Western AL Concerning...Heavy rainfall...Flash flooding possible Valid 161727Z - 162327Z SUMMARY...Increasing coverage of heavy showers and thunderstorms is expected over the next several hours. Some cell-training is expected which may result in at least a localized threat of flash flooding. DISCUSSION...The GOES-East clean IR satellite imagery shows an expanding cluster of cold-topped convection (with a few overshooting tops) over areas of southwest MS, with additional activity developing farther back to the southwest down into areas of central LA. The activity if forming out ahead of a cold front gradually advancing east through the lower MS Valley which is intercepting a moist and increasingly unstable boundary layer. The environment over the next several hours is expected to be conducive for expanding clusters of multicell and supercell convection as additional boundary layer heating via solar insolation works in tandem with rather strong shear profiles for organized convective development. MLCAPE values are forecast by the HRRR to increase to 1000 to 2000 J/Kg, with effective bulk shear values of locally over 50 kts. The airmass is rather moist with PWs nosing upwards of 1.5 inches based off some of the latest GPS-derived data monitors. The level of convective organization with a moderately strong thermodynamic environment should favor convection with rather heavy rainfall rates, and the 12Z HREF guidance does support some potential for rainfall rates to reach as high as 1.5 to 2 inches/hour with the stronger cells. One other facilitator of this will be the presence of a 40+ kt southwest low-level jet to maintain a relatively strong corridor of moisture transport. As convection develops and expands off to the northeast over the next several hours, some occasional instances of cell-training will be possible. This will favor some swaths of heavier rainfall totals, and the recent HRRR guidance has been trending wetter and does advertise some localized streaks of 2 to 4+ inch rainfall totals. A couple of the 12Z HREF members including the ARW2 and FV3-LAM are similarly heavy with their QPF. A localized threat of flash flooding will be possible given the heavy rainfall rates and cell-training concerns, with the urban corridors at greatest risk of seeing runoff problems. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!4hzZph8cnx6_A2kNlDXwVsjx1oNCY5_QhoHubWUVWA61xpQqMcqJ5Nb7BKKQZFdmAIzw= TFpdoUZWZPjWpEEZYYtPo84$ for graphic product... ATTN...WFO...BMX...JAN...LCH...LIX...MOB... ATTN...RFC...LMRFC...SERFC...NWC... LAT...LON 33278824 33098733 32168775 31048941 30279079=20 30019164 30239216 30619205 31389130 32488983=20 =20=20=20=20=20=20=20=20=20=20=20=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) .