SPC AC 090600

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0100 AM CDT Thu May 09 2024

   Valid 091200Z - 101200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM
   CENTRAL/NORTH TX EASTWARD ACROSS THE SOUTHEAST INTO SOUTHERN SC...

   ...SUMMARY...
   Very large hail with multiple supercells appears probable across
   parts of central Texas into the ArkLaTex vicinity Thursday afternoon
   and evening. A broader corridor of severe hail and damaging-wind
   potential will extend from east Texas into the lower Mississippi
   Valley and Southeast.

   ...Synopsis...
   Another very active severe weather episode is possible later today,
   with the main threat expected along a generally west-to-east
   corridor from parts of north/central TX into the Southeast. Some
   severe potential will persist across parts of AL/GA during the day,
   with at least some risk of all severe hazards. Supercells capable of
   producing very large to giant hail and possibly a couple of
   tornadoes are possible across parts of central/north TX during the
   afternoon and early evening. One or more fast-moving MCSs may move
   eastward across parts of the Southeast tonight, potentially
   producing a swath of damaging wind. 

   A large, positively tilted upper-level trough will cover much of the
   CONUS on Thursday. An embedded mid/upper-level low will move slowly
   and perhaps retrograde toward the eastern Great Basin, with moderate
   to strong westerly midlevel flow extending eastward across the
   southern Plains and Southeast. A cold front will move across parts
   of the southern Plains and Southeast through the day, with the
   frontal position potentially influenced by widespread antecedent
   convection that will likely last into the morning. 

   ...MS/AL/GA/SC during the day...
   A cluster of strong to potentially severe storms may be ongoing
   across parts of MS/AL/GA/SC at the start of the forecast period.
   This convection may expand in coverage through the morning within
   broad low-level warm advection, and generally spread
   east-southeastward toward the coast. Downstream of this convection,
   diurnal heating of a very moist airmass will support moderate to
   potentially strong buoyancy, while favorable deep-layer shear will
   continue to support organized convection. A mixture of supercells
   and bowing segments will be possible, with an attendant threat of
   damaging gusts, hail, and possibly a few tornadoes. 

   ...Parts of central/north TX during the afternoon...
   There is some signal for isolated storm development this morning
   across western portion of the Edwards Plateau, on the western fringe
   of deeper low-level moisture and strong instability. Any storm that
   matures in this area could quickly evolve into a supercell with a
   threat of very large hail and localized severe gusts. 

   If any early development persists northeastward, or else does not
   disrupt the warm sector, then a supercell threat is expected to
   evolve into parts of central/north TX during the afternoon, both
   near the dryline/front intersection and also potentially to the cool
   side of the front. Strong to extreme instability (with MLCAPE across
   the warm sector potentially in the 3000-4000 J/kg range), favorable
   deep-layer shear, and elongated/straight hodographs will support a
   threat of very large to giant hail. Low-level flow/shear will be
   rather weak, but some tornado threat could also evolve, especially
   where storm and/or boundary interactions take place.

   ...Central/north TX eastward across the Southeast during the
   evening/overnight...
   A majority of HREF guidance and also some larger-scale guidance
   (such as the NAM/GFS/ECMWF) depict potential for development of a
   fast-moving MCS that would move from parts of central/north TX
   across the Southeast into the overnight hours. The pattern generally
   favors this scenario, with favorable downstream moisture/instability
   and moderate to strong westerly flow aloft. If this scenario pans
   out, then a long swath of damaging winds will be possible from TX
   across much of the Southeast, including the potential for gusts of
   greater than 75 mph, and possibly brief line-embedded tornadoes.
   However, given the inherent uncertainty with late-period MCS
   development, combined with uncertainty regarding the evolution of
   diurnal convection into MS/AL/GA, no increase in unconditional wind
   probabilities has been made with this outlook. The 30% wind area has
   been expanded southward, based on the latest guidance. 

   ...North Carolina into the Mid Atlantic and Ohio Valley...
   Some early convection may persist into parts of NC and the Mid
   Atlantic, with a threat of isolated damaging wind. Some
   redevelopment will be possible into parts of IN/OH, where weak to
   moderate buoyancy may persist in advance of a cold front. Deep-layer
   shear will remain sufficient for organized convection, and a few
   stronger cells/clusters capable of isolated hail and damaging wind
   will be possible.

   ..Dean/Wendt.. 05/09/2024

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