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

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z