MESOSCALE DISCUSSION 2259
   NWS STORM PREDICTION CENTER NORMAN OK
   1115 AM CDT TUE OCT 18 2011
   
   AREAS AFFECTED...SRN AND WRN FL
   
   CONCERNING...SEVERE POTENTIAL...WATCH LIKELY 
   
   VALID 181615Z - 181745Z
   
   A TORNADO THREAT IS EXPECTED TO DEVELOP THIS AFTERNOON ACROSS SRN
   AND CNTRL FL WITH AN ISOLATED WIND DAMAGE THREAT ALSO POSSIBLE. IN
   RESPONSE...A TORNADO WATCH WILL LIKELY BECOME NECESSARY ACROSS THE
   SRN FL PENINSULA AND POSSIBLE PARTS OF CNTRL FL IN THE 17Z TO 18Z
   TIMEFRAME
   
   AN UPPER-LEVEL TROUGH AND ASSOCIATED SFC LOW IN THE NERN GULF OF
   MEXICO WILL CONTINUE TO MOVE NEWD TOWARD THE WRN COAST OF FL THIS
   AFTERNOON. TO THE EAST OF THE SFC LOW...A WELL-DEFINED 35 TO 45 KT
   JET NEAR 850 MB WILL MOVE INTO SRN FL RESULTING IN AN INCREASE IN
   LOW-LEVEL MOISTURE WITH PRECIPITABLE WATER VALUES INCREASING TO
   AROUND 2.50 INCHES. THIS WILL RESULT IN LOW CLOUD BASES AS A
   DEVELOPING SQUALL-LINE APPROACHES THE SOUTHWEST COAST THIS
   AFTERNOON. IN ADDITION...THE JET MAX WILL INCREASE LOW-LEVEL SHEAR
   OVER THE NEXT FEW HOURS WITH FORECAST SOUNDINGS EARLY THIS AFTERNOON
   SHOWING 0-1 KM SHEAR VALUES OF 30 TO 35 KT. THIS ENVIRONMENT WILL BE
   FAVORABLE FOR ROTATING CELLS AHEAD OF THE LINE AND EMBEDDED IN THE
   LINE ITSELF WITH TORNADOES POSSIBLE. THE TORNADO THREAT IS EXPECTED
   TO CONTINUE INTO THE LATE AFTERNOON AS THE SQUALL-LINE MOVES ACROSS
   SCNTRL FL. A FEW DAMAGING WIND GUSTS MAY ALSO OCCUR WITH
   BOWING-SEGMENTS EMBEDDED IN THE LINE.
   
   ..BROYLES.. 10/18/2011
   
   
   ATTN...WFO...MFL...MLB...KEY...TBW...
   
   LAT...LON   27578019 27668071 27418122 27218190 27048225 26608230
               26098200 25688171 25418141 25098112 25008081 25038033
               25238011 25657994 26147985 27047994 27578019