SPC AC 210537

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1137 PM CST Mon Dec 20 2021

   Valid 211200Z - 221200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   THE CENTRAL AND SOUTHERN FLORIDA PENINSULA...

   ...SUMMARY...
   Scattered strong convection is expected across parts of the Florida
   Peninsula from early this morning into the afternoon. Some of this
   activity may produce damaging winds and perhaps a few tornadoes.

   ...FL Peninsula...

   Low-latitude trough has progressed into the lower MS Valley-central
   Gulf Basin late this evening. Persistent deep convection has mostly
   been confined to more buoyant regions of the southern Basin, roughly
   south of 27N. LLJ is forecast to strengthen offshore prior to
   daybreak then translate across the central Peninsula ahead of the
   progressive short wave. This evolution should result in higher
   PW-air mass advecting inland as low-level trajectories become more
   favorable prior to 20/12z. Latest thinking is current organized
   strong/severe thunderstorm cluster (or subsequent derivative of this
   activity) located about 140mi southwest of FMY will likely approach
   the southern FL Gulf Coast around daybreak. Boundary-layer recovery
   is expected to be sufficient for maintaining organized convection as
   it spreads northeast ahead of the surface low/trailing boundary.
   Forecast soundings across the central/southern Peninsula support
   organized updrafts, and while lapse rates are not that steep,
   significant moistening and strong wind fields suggest supercells are
   possible. Sufficient shear will likely exist to warrant at least
   some threat for a few tornadoes along with damaging winds. The
   primary risk for severe will be during the morning along the Gulf
   Coast, shifting to eastern FL Peninsula during the afternoon.

   ..Darrow/Bentley.. 12/21/2021

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