SPC AC 100422

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1122 PM CDT Fri Apr 09 2021

   Valid 111200Z - 121200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF
   FLORIDA...

   ...SUMMARY...
   Isolated strong to severe thunderstorms are possible on Sunday
   across parts of the eastern Florida Panhandle and the Florida
   Peninsula.

   ...Synopsis...

   An upper low over the Midwest and its attendant trough extending
   southeastward through the southeast U.S. will pivot northeast on
   Sunday. The upper low will become oriented over the lower Great
   Lakes by Monday morning, while the associated trough extends along
   the Mid-Atlantic coast and offshore the southeastern U.S. coast.
   This should maintain moderate west/southwesterly flow from the
   Mid-Atlantic/central Appalachians southward through Florida for much
   of the period. A surface low stacked beneath the upper low over the
   Great Lakes will not move much, but instead weaken through the
   period. A cold front will extend from western PA along the
   Appalachians and into southeast AL and then just offshore from
   south-central LA. While the southern most segment of the front will
   stall along the central Gulf coast, much of the front should shift
   eastward, moving offshore the Mid-Atlantic cost and into northern
   Florida by Monday morning. 

   A mature MCS/QLCS is forecast to be ongoing across parts of northern
   Florida Sunday morning. Some severe threat could persist with this
   system as it tracks southeastward across the Florida Peninsula
   through the day.

   ...Florida...

   Most guidance has a mature MCS/QLCS over northern FL at the
   beginning of the period, and the evolution of the severe threat on
   Sunday will depend on where exactly this activity is located during
   the morning, and specifically how far south any outflow may develop
   early in the period. This could impact how much CINH exists and how
   much recovery can occur through peak heating. Nevertheless, mid to
   upper 60s dewpoints will be in place, and at least weak
   destabilization should occur amid 35-45 kt effective shear. This
   should be sufficient to support at least a low-end threat for
   locally damaging gusts and hail.

   ...Delmarva into parts of eastern PA...

   Modest low level moisture is expected to extend northward into the
   Chesapeake vicinity, with mid 50s to near 60 F surface dewpoints
   forecast. Stronger forcing closer to the surface and upper lows,
   along with a better-defined cold front surging eastward should
   provide focus of isolated thunderstorm development during the
   afternoon. Instability is currently forecast to remain weak,
   generally less than 1000 J/kg, along with modest vertical shear.
   Midlevel lapse rates near 7 C/km and a deeply mixed boundary layer
   resulting in steep low level lapse rates also will overspread the
   region. Some locally gusty winds or small hail could accompany any
   stronger cells. However, weak low level winds and overall modest
   thermodynamic/kinematic environment will preclude severe
   probabilities at this time.

   ..Leitman.. 04/10/2021

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