MESOSCALE DISCUSSION 0278
   NWS STORM PREDICTION CENTER NORMAN OK
   0111 PM CDT MON MAR 18 2013
   
   AREAS AFFECTED...SCNTRL AL...WRN GA
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 181811Z - 181945Z
   
   PROBABILITY OF WATCH ISSUANCE...60 PERCENT
   
   SUMMARY...A SEVERE THREAT IS LIKELY TO DEVELOP THIS AFTERNOON ACROSS
   SCNTRL AL AND WRN GA. A FEW TORNADOES ALONG WITH A THREAT FOR
   ISOLATED LARGE HAIL AND WIND DAMAGE WILL BE POSSIBLE WITH THE MORE
   INTENSE CELLS. WW ISSUANCE WILL BE POSSIBLE FOR THIS AFTERNOON
   ACROSS PARTS OF SRN AND ERN AL EXTENDING NEWD INTO WRN GA.
   
   DISCUSSION...THUNDERSTORMS ARE BEGINNING TO DEVELOP ACROSS SCNTRL AL
   AND IN THE WRN FL PANHANDLE AT THE ERN EDGE OF MODERATE INSTABILITY.
   OBJECTIVE ANALYSIS SHOWS MLCAPE VALUES IN THE 1000 TO 1500 J/KG
   RANGE ACROSS THE WRN PART OF THE MCD AREA AND INSTABILITY SHOULD
   CONTINUE TO INCREASE OVER THE NEXT FEW HOURS. THE CELLS ARE
   INITIATING IN A WEAKLY FORCED ENVIRONMENT DUE TO SFC HEATING BUT MAY
   INCREASE IN COVERAGE AS A BAND OF LARGE-SCALE ASCENT APPROACHES LATE
   THIS AFTERNOON. A MODERATE TO STRONG WIND SHEAR ENVIRONMENT EXISTS
   ACROSS THE MCD AREA WITH 0-6 KM SHEAR ESTIMATED AT 40 TO 50 KT. IN
   ADDITION...THE WSR-88D VWP IN SW AL SHOWS ABOUT 25 KT OF 0-1 KM
   SHEAR WITH SUBSTANTIAL DIRECTIONAL SHEAR IN THE BOUNDARY LAYER. THIS
   SHOULD ENABLE CELLS TO ROTATE AND SUPERCELL DEVELOPMENT WILL BE
   POSSIBLE. A TORNADO AND ISOLATED LARGE HAIL THREAT SHOULD EXIST WITH
   SUPERCELLS. WIND DAMAGE WILL ALSO BE POSSIBLE AS CELLS MATURE LATER
   THIS AFTERNOON.
   
   ..BROYLES/HART.. 03/18/2013
   
   
   ATTN...WFO...FFC...TAE...BMX...MOB...
   
   LAT...LON   32828391 33118419 33258464 33228538 32998590 32458708
               32128744 31798753 31238740 30898670 30928602 31138514
               31958386 32828391