MESOSCALE DISCUSSION 0530
   NWS STORM PREDICTION CENTER NORMAN OK
   0651 PM CDT SUN APR 19 2009
   
   AREAS AFFECTED...MUCH OF CNTRL AND SRN AL
   
   CONCERNING...TORNADO WATCH 173...
   
   VALID 192351Z - 200045Z
   
   THE SEVERE WEATHER THREAT FOR TORNADO WATCH 173 CONTINUES.
   
   THREAT FOR ISOLATED TORNADOES...LARGE HAIL AND DAMAGING WIND WILL
   PERSIST THROUGH EARLY EVENING. SEVERE THREAT MAY SHIFT A LITTLE
   FARTHER EAST OF CURRENT WW AND AS A RESULT...WW 173 HAS BEEN
   EXTENDED EAST A FEW COUNTIES INTO ERN AL.
   
   SCATTERED SUPERCELLS CONTINUE ALONG AND EAST OF A PRE-FRONTAL
   CONVERGENCE AXIS THAT EXTENDS FROM MIDDLE TN THROUGH WRN AL. ZONE OF
   GREATER INSTABILITY WITH MLCAPE FROM 500-1000 J/KG EXTENDS FROM ERN
   MS THROUGH THE WRN HALF AL AND CORRESPONDS TO AXIS OF HIGHER
   BOUNDARY LAYER MOISTURE WITH LOW-MID 60S DEWPOINTS. SOME OF THE
   STORMS ARE APPROACHING THE ERN EDGE OF WW 173 ACROSS ERN AL WHERE
   INSTABILITY AND MOISTURE ARE MORE LIMITED. SWLY LOW LEVEL JET WILL
   PERSIST ACROSS AL DURING THE EVENING. THIS MAY CONTRIBUTE TO MOIST
   ADVECTION AND MODEST DESTABILIZATION OVER ERN AL NEXT FEW HOURS
   WHERE LOW LEVEL HODOGRAPHS AND BULK SHEAR WILL CONTINUE TO SUPPORT
   SUPERCELLS. THE SEVERE THREAT IS EXPECTED TO WANE BY MID TO LATE
   EVENING AS THE BOUNDARY LAYER BEGINS TO COOL AND THE LOW LEVEL JET
   SHIFTS FARTHER NE INTO THE SRN APPALACHIANS WHERE INSTABILITY WILL
   REMAIN MUCH MORE LIMITED.
   
   ..DIAL.. 04/19/2009
   
   
   ATTN...WFO...BMX...MOB...
   
   LAT...LON   33698547 31898539 30868821 32858763 33698547