SPC AC 090726

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0226 AM CDT Tue Apr 09 2024

   Valid 111200Z - 121200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN PARTS OF THE
   SOUTHEAST AND THE UPPER OH VALLEY...

   ...SUMMARY...
   Scattered severe thunderstorms are possible on Thursday across parts
   of the Southeast and the Upper Ohio Valley.

   ...Synopsis...
   A full-latitude mid/upper trough should be centered near the MS
   Valley at 12Z Thursday, comprised of two primary shortwave impulses.
   The southern-stream impulse should pivot northeast and accelerate as
   the northern-stream impulse becomes the dominant embedded feature. A
   steadily deepening surface cyclone should track northeast from the
   Lower OH Valley to the Lake Huron vicinity during the period. 

   ...Southeast...
   A convective swath should be ongoing from parts of the FL Panhandle
   into GA on Thursday morning. The southern portion of this activity
   will have the best chance to maintain a damaging wind and embedded
   tornado threat from late morning into the early afternoon as
   stronger boundary-layer heating occurs across FL. Large-scale ascent
   will weaken with southern extent through the day given the
   northeastward track of the surface cyclone, in addition to low-level
   winds becoming more veered in time over the FL Peninsula. 

   Farther north, fast 850-700 mb winds should be coincident with a
   plume of mid to upper 60s advecting north into the Carolinas.
   However, diabatic surface heating may be quite limited by abundant
   downstream cloudiness/stratiform rain north of the deeper convection
   in FL. Mid-level lapse rates will also be weak and overall
   instability may remain meager. Still, the high-shear/low-CAPE setup
   with at least low-topped convection likely persisting until it
   progresses off the coast will foster some threat for sporadic
   damaging winds and a few brief tornadoes, mainly midday through
   early evening. How far north and how long the severe threat persists
   into Thursday night is unclear, but low probabilities appear
   warranted through at least the Lower Mid-Atlantic States. 

   ...Upper OH Valley...
   A synoptically favorable corridor for a few supercells and organized
   clusters should develop east of the gradually deepening surface
   cyclone track. This region should have a period where an
   overspreading mid-level dry slot coincides with the diurnal heating
   cycle, before early afternoon convection develops within the
   left-exit region of the strong mid-level jet across the Southeast
   and southern Appalachians. While MLCAPE will remain weak, a
   meridional supercell wind profile should be present before low-level
   flow becomes veered from the southwest. A couple tornadoes, isolated
   to scattered damaging winds, and isolated severe hail are possible.

   ..Grams.. 04/09/2024

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