Mesoscale Discussion 1837
   NWS Storm Prediction Center Norman OK
   0140 AM CST Mon Dec 07 2020

   Areas affected...South FL

   Concerning...Severe potential...Watch unlikely 

   Valid 070740Z - 070915Z

   Probability of Watch Issuance...20 percent

   SUMMARY...A tornado and locally damaging winds will be possible if a
   supercell can become sustained over the Everglades and spread east
   towards the southeast Florida coast through dawn.

   DISCUSSION...A lone thunderstorm embedded along the southern edge of
   a broad swath of stratiform rain recently acquired weak but
   transient low-level rotation across southeast Collier county. This
   convection appears to be located near the surface front, along the
   instability gradient which peaks farther south with MLCAPE of
   1000-1500 J/kg across the Keys per the 06Z Key West RAOB and 07Z
   mesoanalysis. VWP data from Miami has sampled strengthening
   low-level southerlies over the past 1-2 hours and these should
   further increase in speed as they veer to the southwest prior to
   daybreak. The net result should be maintenance of 0-1 km SRH around
   200 m2/s2, conditionally supportive of a tornado and locally
   damaging wind threat through about dawn. Primary uncertainty is the
   degree of thunderstorm coverage beyond this initial cell during the
   next few hours, with the bulk of ongoing storms still holding well
   west of the Keys in the southeast Gulf.

   ..Grams.. 12/07/2020

   ...Please see www.spc.noaa.gov for graphic product...

   ATTN...WFO...MFL...KEY...

   LAT...LON   26208088 26558056 26848022 26697981 26187986 25707995
               25408020 25248041 25308083 25818103 26208088