Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Jun 14 2023 05:58:56 ACUS01 KWNS 140558 SWODY1 SPC AC 140557 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1257 AM CDT Wed Jun 14 2023 Valid 141200Z - 151200Z ....THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FROM NORTHEAST LOUISIANA INTO CENTRAL/SOUTHERN MISSISSIPPI AND ALABAMA...AND SOUTHWEST GEORGIA... ....SUMMARY... Significant severe thunderstorms capable of producing all severe hazards, including very large hail, swaths of intense wind gusts/damage, and tornadoes, are possible across much of the Lower Mississippi Valley vicinity and Southeast states today into tonight. ....ArkLaTex into the Southeast... A complex forecast scenario with multiple rounds of intense severe thunderstorms is expected to evolve today from the ArkLaTex into the Lower MS Valley and Southeast vicinity. All severe hazards are expected, including very large hail (some greater than 3 inches in diameter), swaths of intense wind gusts (greater than 70 kt/80 mph), and tornadoes (a couple strong). As a result, a Moderate risk (level 4 of 5) has been introduced with the initial Day 1 outlook. A series of mid/upper shortwave impulses are expected to shift east across the Lower MS Valley and Southeast today in strong west/southwesterly mid/upper flow. Consistency among various forecast guidance shows at least 40-50 kt west/southwest flow between 850-700 mb with 60+ kt at 500 mb. A plume of very steep lapse rates will overspread the region, and 500 mb temperatures around -10 to -11 C will be common. Forecast soundings indicate midlevel lapse rates around 8-8.5 C/km over the region. These lapse rates are near the 70-year period of record max according to sounding climatology for this area of the country for this time of year. Beneath these steep midlevel lapse rates and strong flow aloft, a very moist airmass will be in place, with dewpoints generally in the 68-75 F range. This will result in strong destabilization with MLCAPE values exceeding 3000 J/kg stretching from northeast TX through southern AL/GA/FL Panhandle vicinity. Periods of early morning convection (prior to 12z this morning) are expected across portions of the region. This activity may persist through the morning into midday/early afternoon. This should result in a convectively reinforced surface boundary oriented roughly west to east from northern LA into central MS/AL/GA, though there is some uncertainty in how far south this boundary will reside. Any convection north of this boundary will be elevated, but still may pose a risk for large hail. Near and south of the boundary, all severe hazards are possible. Morning activity may see a relative lull for a few hours during the afternoon as the initial shortwave impulse shifts east and offshore the Atlantic coast before another, stronger shortwave trough develops east across the region during the evening. The expectation is that multiple rounds of severe storms are expected today into tonight. Locations may see a mix of supercells and intense bowing segments during the day, with potential for a derecho developing near the Lower MS Valley and shifting east/southeast toward the central Gulf Coast vicinity during the evening. ....North TX Vicinity... A couple of supercells may be ongoing this morning across north Texas. This activity will be capable of producing large to very large hail before shifting east and weakening. Additional storms are expected to develop during the afternoon and again pose a risk of large hail. If trends continue, the Slight risk (level 2 of 5) may need to be extended westward across portions of north TX. ....Northeast... Modest air mass destabilization is expected across the region ahead of an upper low. One or more north-south orientated bands of convection are expected as ascent attendant to this cyclone moves through. Instability will be modest, mitigated by weak lapse rates, but a few stronger gusts and small hail are possible as these lines move east/northeast through the afternoon. ...Leitman/Bentley.. 06/14/2023 $$ = = = 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) .