MESOSCALE DISCUSSION 2257
   NWS STORM PREDICTION CENTER NORMAN OK
   0503 PM CDT MON OCT 17 2011
   
   AREAS AFFECTED...UPR FL KEYS
   
   CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 
   
   VALID 172203Z - 172300Z
   
   AREA OF CONVECTION 25 ESE OF MTH MAY POSE A BRIEF THREAT FOR A
   WATERSPOUT DURING THE NEXT FEW HRS...AS WELL AS A TORNADO IF
   ACTIVITY CAN MOVE ACROSS THE UPR FL KEYS. OVERALL SVR WEATHER
   POTENTIAL WILL REMAIN LIMITED...PRECLUDING THE NEED FOR A WW.
   
   HI-RES KBYX RADAR SHOWS A LINE OF SHOWERS/ISOLATED EMBEDDED
   THUNDERSTORM LOCATED ROUGHLY 25 ESE OF MTH AT 2150Z. THIS ACTIVITY
   HAS FOR THE MOST PART REMAINED STATIONARY DURING THE LAST HR...WITH
   ONLY A SLIGHT DRIFT TO THE NNE OBSERVED IN RADAR IMAGERY. LATEST VWP
   FROM BYX SHOWS E-NELY SURFACE WINDS VEERING TO SLY AT 3 KM
   AGL...RESULTING IN ENLARGED HODOGRAPH STRUCTURE AND 0-1 KM SRH
   VALUES FROM 100-200 M2 S-2. THIS SHEAR PROFILE APPEARS TO BE AIDING
   IN RELATIVELY STRONG UPDRAFT ROTATION IN THE SRN MOST CELL...DESPITE
   THE PRESENCE OF WEAK LAPSE RATES AND INSTABILITY /I.E. MLCAPE VALUES
   AOB 500 J PER KG/. GIVEN THE FAVORABLE SHEAR...A SHORT TERM THREAT
   FOR A WATERSPOUT WILL EXIST WITH THIS CONVECTION...AS WELL AS A
   TORNADO IF STORMS CAN MOVE ACROSS THE UPR KEYS. DURING THE EVENING
   AND OVERNIGHT HRS...MODEL GUIDANCE INDICATES LOW-LEVEL VERTICAL WIND
   SHEAR WILL GENERALLY WEAKEN OVER THE REGION...WHICH SHOULD DECREASE
   THE THREAT FOR A BRIEF WATERSPOUT/TORNADO.
   
   ..GARNER.. 10/17/2011
   
   
   ATTN...WFO...MFL...KEY...
   
   LAT...LON   24718026 24408099 24648123 24858112 25118048 24718026