SPC AC 211713

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1213 PM CDT Sun Apr 21 2024

   Valid 221200Z - 231200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
   SOUTHEASTERN FLORIDA PENINSULA...

   ...SUMMARY...
   Strong to locally severe thunderstorms, capable of marginally severe
   wind gusts and hail, will be possible across the central and
   southern Florida Peninsula on Monday.

   ...Synopsis...
   A cold front currently draped across the southeastern states to the
   northern Gulf will continue to slowly push south/southeast over the
   next 24-48 hours. This feature should reach the central to southern
   FL peninsula by mid-day Monday. Thunderstorms will likely be focused
   along this boundary as it pushes towards far south FL by late Monday
   evening. Across the Plains, more isolated thunderstorms will be
   possible along a cold front and in the vicinity of a surface low
   from northeast CO to the upper MS River Valley.

   ...South Florida...
   Heating of a moist air mass currently in place across south FL,
   combined with modest mid-level lapse rates, should support MLCAPE
   values between 1000-1500 J/kg ahead of the approaching front.
   Although low-level flow will be somewhat weak, winds aloft will be
   sufficiently strong to support effective bulk wind differences on
   the order of 30-40 knots. Elongated, nearly straight hodographs
   should favor splitting cells with the potential for a couple of
   right-moving supercells that will pose a large hail threat. However,
   storm motions and deep-layer shear vectors should largely be along
   the surface boundary, and weak inhibition may favor multiple
   thunderstorms along the front by peak heating. These factors could
   favor upscale growth of cells into clusters by late afternoon, which
   may limit the supercell potential. Regardless, both
   discrete/semi-discrete cells and/or more organized clusters should
   pose a damaging wind threat given low-level lapse rates approaching
   8 C/km by mid afternoon. Latest CAM guidance suggests the severe
   threat is most likely to manifest across the southern portion of the
   Marginal risk area - particularly in the Miami vicinity as the front
   arrives by late afternoon. However, a few strong/severe storms will
   be possible late morning further north. 

   ...Eastern CO to northwest KS...
   Dry conditions are prevalent across the Plains in the wake of the
   recent frontal passage. However, modified mid-level Pacific moisture
   associated with an approaching shortwave trough (currently over
   portions of the Pacific Northwest) should overspread parts of the
   central to northern High Plains by Monday afternoon. Modest
   mid-level moisture atop a deep, well-mixed boundary layer may
   support sufficient buoyancy for a few thunderstorms with an
   attendant risk for dry downbursts along a weak surface cold front.
   Strong to severe outflow gusts are possible based on the forecast
   thermodynamic profiles, but do not appear to be probable based on
   convective signals in latest guidance and discrepancies between
   solutions regarding mid-level saturation (and resultant buoyancy).
   Forecast trends will be monitored for the need for low-end,
   wind-driven risk probabilities.

   ..Moore.. 04/21/2024

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