Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Dec 14 2022 20:00:17 ACUS01 KWNS 142000 SWODY1 SPC AC 141958 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0158 PM CST Wed Dec 14 2022 Valid 142000Z - 151200Z ....THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF SOUTHEASTERN LOUISIANA...SOUTHERN/CENTRAL MISSISSIPPI...AND SOUTHERN/WESTERN ALABAMA... ....SUMMARY... Strong tornadoes and damaging thunderstorm gusts are expected this afternoon and evening across southern parts of Louisiana, Mississippi, and Alabama, and portions of the Florida Panhandle. ....20Z Update... Multiple supercells with strong low-level rotation are ongoing this afternoon across parts of southeastern LA into southern MS. The 18Z observed sounding from LIX shows ample low-level shear is present to support rotating updrafts. Moderate instability is also present to foster robust thunderstorms, even with a modest mid-level inversion noted around 550 mb. Any of these supercells will remain capable of producing strong tornadoes this afternoon given the strength of the low-level flow associated with a 40-50 kt south-southwesterly low-level jet. See Mesoscale Discussion 2032 for additional details on the short-term threat for strong tornadoes across southeastern LA, southern MS, and southwestern AL. The northern extent of appreciable severe risk is denoted by a warm front currently extending from western into southern AL. As convection continues eastward this evening, it should begin to outpace the best low-level moisture return. Still, the presence of strong low-level and deep-layer shear and sufficient boundary-layer instability should support a continued threat for tornadoes and damaging winds as this activity spreads across parts of southern/central AL and the western FL Panhandle this evening and tonight. Some of these tornadoes could be strong. Eventually, convection should slowly weaken with eastward extent into north FL and southern GA. But, it could still pose an isolated severe threat through early Thursday morning. ...Gleason.. 12/14/2022 ..PREV DISCUSSION... /ISSUED 1025 AM CST Wed Dec 14 2022/ ....Active severe weather event is anticipated this afternoon and evening for portions of the central Gulf Coast states... ....LA/MS/AL... Morning water vapor imagery shows an intense and progressive shortwave trough rotating across OK/TX. This feature is expected to become negatively tilted this evening over AR, with strong large-scale forcing overspreading much of the mid/lower MS Valley. Strong southerly low-level winds have established a very moist and potentially unstable air mass over parts of LA/MS/AL, with dewpoints in the 70s and visible satellite showing considerable breaks in the low clouds. This should result in ample CAPE by mid-afternoon. A consensus of 12z CAM guidance indicates that discrete supercell development will commence this afternoon over southeast LA into southern MS. This activity will likely persist through the evening and track into western and southern AL. Forecast soundings show very strong low-level vertical shear and favorable deep-layer shear for tornadoes, along with sufficient CAPE for robust thunderstorms. Low-level winds are expected to strengthen further during the afternoon with the approach of the upper trough. Tornadoes, including the possibility of strong and long-track tornadoes, are the primary concern today. Given the consistent signal in 12z guidance for numerous supercells, the favorable CAPE/shear environment, and the impressive nature of the shortwave trough, have opted to upgrade to MDT risk for portions of the area. $$ = = = 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) .