SPC AC 110551

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1251 AM CDT Wed Sep 11 2024

   Valid 121200Z - 131200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE FL
   PANHANDLE TO CENTRAL AL AND IN EASTERN MT...

   ...SUMMARY...
   On Thursday, a few tornadoes will be possible, mainly in the morning
   and afternoon from the Florida Panhandle to north-central Alabama.
   Scattered large hail and severe gusts will also be possible across
   the eastern Montana vicinity during the afternoon to early evening.

   ...FL Panhandle to the TN Valley...
   Hurricane Francine is forecast by NHC to be in a weakening phase
   from a tropical storm to a depression on Thursday, as it steadily
   moves north from parts of western/central MS into the Mid-South.
   With this process occurring throughout D2, tornado potential should
   be focused during the first half of the period. Rather enlarged
   low-level hodographs initially should gradually shrink from south to
   north, but will remain overlapped with rich 70s surface dew points
   through at least the afternoon. Consensus of CAM guidance largely
   suggests multiple opportunities for convective bands during this
   time frame. Primary threat in the morning should initially be
   confined across the FL Panhandle into south AL. This should shift
   north along the leading edge of the rich tropical moisture into
   central to perhaps north AL during the afternoon. The northern
   extent of the low-probability tornado threat over the TN Valley
   appears nebulous, where scant surface-based buoyancy can become
   coincident with large SRH. 

   ...Eastern MT vicinity...
   A northern Rockies to Great Basin shortwave trough will move
   gradually east into the northern High Plains to central Rockies by
   Thursday evening. Guidance remains highly consistent with the
   ejection of an embedded impulse and attendant meridional mid-level
   jetlet impinging on the eastern MT/WY region during the late
   afternoon to early evening. This will increase large-scale ascent
   and deep-layer shear, while being favorably timed with peak
   boundary-layer heating. 

   Spread in guidance is greater with the degree of available buoyancy
   as boundary-layer moisture remains limited. But a ribbon of low to
   mid 50s surface dew points appears plausible on the backside of a
   deep surface cyclone drifting from far eastern MT into south SK.
   This would support a confined corridor of at least weak buoyancy,
   which should be enhanced by cooling mid-level temperatures with the
   approaching trough. Scattered thunderstorms should develop near the
   WY/MT border area during the mid to late afternoon and quickly
   advance north-northeast. Amid a highly elongated mid to upper
   hodograph, long-lived mid-level rotation and small-scale bowing
   segments may occur, capable of producing swaths of large hail and
   severe gusts through about dusk.

   ..Grams.. 09/11/2024

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