Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Nov 29 2022 20:01:44 ACUS01 KWNS 292001 SWODY1 SPC AC 291959 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0159 PM CST Tue Nov 29 2022 Valid 292000Z - 301200Z ....THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND TONIGHT OVER PARTS OF NORTHEAST LOUISIANA...EXTREME SOUTHEAST ARKANSAS...CENTRAL AND NORTHERN MISSISSIPPI...AND NORTHWEST ALABAMA... ....SUMMARY... Strong tornadoes, very large hail, and severe wind gusts are forecast this afternoon into the overnight period across parts of the lower to mid Mississippi Valley, Mid-South and parts of the Southeast. ....20Z Update... A regional tornado outbreak still appears possible from northern LA into central/northern MS and potentially into western AL. Rich low-level moisture has streamed northward with the aid of a strong low-level jet, as steep midlevel lapse rates (greater than 8 C/km on 12Z SHV sounding) have overspread the region from the west. MLCAPE has increased into the 1500-2000 J/kg range across the warm sector, and storms are gradually increasing in coverage and intensity across parts of LA/MS. Strong and favorably veered wind profiles will support several long-lived supercells late this afternoon into this evening. With relatively weak low-level lapse rates, it may take some time for storms to become tornadic, but a few long-track strong tornadoes will be possible late this afternoon into tonight as supercells mature and move northeastward. The primary change at 20Z is to expand the Marginal Risk slightly eastward across a larger portion of western GA, southeast AL, and FL Panhandle. This change was made to account for the possibility of nocturnal storms reaching these areas prior to the end of the forecast period at 12Z. ...Dean.. 11/29/2022 ..PREV DISCUSSION... /ISSUED 1021 AM CST Tue Nov 29 2022/ ....Regional Outbreak of severe thunderstorms and tornadoes is forecast today and tonight for parts of the lower Mississippi Valley... ....Lower MS Valley... Morning water vapor imagery shows a broad upper trough over much of the CONUS this morning, with several fast moving shortwave troughs moving across the southwest into the southern Plains. Strong southerly low-level winds have developed across the lower MS Valley, aiding in the rapid return of rich Gulf moisture. Dewpoints in the mid/upper 60s have spread into much of east TX and LA, and should extend into central MS by mid-afternoon. Plentiful low clouds are present, limiting daytime heating. But relatively steep mid-level lapse rates and returning moisture will lead to widespread MLCAPE values of 1000-1500 J/kg later today, with only a weak cap. Vertical shear profiles are very strong throughout the region, with effective SRH values of 200-400 m2/s2 beneath 50+ knots of deep-layer shear. Given the subtle forcing today, relatively long-lived discrete supercell storms are expected with an attendant threat of intense and long-track tornadoes. Present indications are that primary thunderstorm development will begin early this afternoon over parts of LA, spreading quickly into MS. This corridor may see multiple waves of severe convection as storms redevelop upstream through the evening. Along with the strong tornado threat, very large hail and damaging wind gusts may occur with these storms. Consideration was made to introduce a small HIGH risk, but still too much uncertainty in the exact corridor of highest risk since moisture is not yet in place and there is no surface boundary to focus on. $$ = = = 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) .