SPC AC 030548

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1148 PM CST Mon Jan 02 2023

   Valid 031200Z - 041200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM SOUTHEAST
   LOUISIANA TO CENTRAL/SOUTHERN ALABAMA...

   ...SUMMARY...
   Severe thunderstorms are expected across the central Gulf states
   into the Tennessee Valley Tuesday. Tornadoes, damaging winds, and
   large hail are all possible. The greatest risk is expected from
   southeast Louisiana into southern/central Alabama where a couple of
   strong tornadoes are possible.

   ...Central Gulf States/Tennessee Valley...

   Strong mid-level short-wave trough is currently ejecting northeast
   across the central Plains. 500mb speed max affiliated with this
   feature is forecast to translate across MO into IL by 18z. As a
   result strong 500mb height falls (150m in 12hr) will overspread the
   mid MS Valley region as a warm front advances north across central
   IL/IN.

   Latest model guidance suggests the primary synoptic cold front will
   arc from southeast IA-eastern MO-lower Sabine River Valley by 18z,
   then into the lower OH Valley, extending into the lower MS Valley by
   04/06z. Low-level warm advection will likely contribute to early-day
   convection ahead of the aforementioned short wave with the primary
   corridor of strong convection likely extending from western KY into
   northern TN. This band of storms should sag southeast as the
   strongest mid-level forcing spreads north of this region. While
   strong updrafts/scattered severe may be noted with this early
   activity, boundary-layer destabilization across the central Gulf
   states is expected to aid buoyancy for potentially more robust
   convection later in the afternoon. Surface temperatures will likely
   warm into the lower 70s across much of the lower MS Valley into
   central AL. With dew points in the mid 60s to near 70F,
   surface-based CAPE should approach 2000 J/kg in the presence of
   strong shear. Any updrafts that evolve within this environment could
   obtain supercell characteristics. Long-lived updrafts capable of
   generating tornadoes, and even a strong tornado, seem possible.
   Damaging winds are also a risk along with hail.

   While convection that evolves through early evening will not be
   strongly forced, a secondary, notable short-wave trough will eject
   across TX by 06z, and this feature should encourage renewed
   convection during the overnight hours as height falls increase ahead
   of the cold front. Frontal convection should organize and propagate
   across LA/MS into AL after midnight.

   ...IL...

   Surface warm front is forecast to advance north across MO/IL/IN this
   morning. Instability will also increase as dew points recover across
   this region. There is some concern that isolated strong/severe
   thunderstorms could initiate ahead of the cold front over IL around
   17-18z but strengthen downstream where temperatures warm into the
   lower 60s . This activity will be strongly sheared and a few
   supercells may ultimately evolve. If so, hail and wind are possible,
   along with some tornado risk. Have extended severe probabilities
   north into IL to account for this risk.

   ..Darrow/Wendt.. 01/03/2023

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