MESOSCALE DISCUSSION 0626
   NWS STORM PREDICTION CENTER NORMAN OK
   0105 PM CDT WED APR 27 2011
   
   AREAS AFFECTED...MUCH OF AL INTO MIDDLE TN/NORTHWEST GA
   
   CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY 
   
   VALID 271805Z - 271930Z
   
   A LONG DURATION PARTICULARLY DANGEROUS /PDS/ TORNADO WATCH WILL BE
   ISSUED BY MID AFTERNOON FOR MUCH OF AL INTO MIDDLE TN/NORTHWEST
   GA...WITH AN ISSUANCE PROBABLE BY AROUND 19Z.
   
   AMID CLOUD BREAKS...THE AIRMASS CONTINUES TO QUICKLY DESTABILIZE IN
   THE WAKE OF A DECAYING MORNING WEST-EAST BOUNDARY ACROSS AL...AND TO
   THE SOUTH OF A MORE RECENT MCS-INDUCED BOUNDARY/COLD POOL ACROSS FAR
   NORTHERN AL. WITH A CLASSIC/SYNOPTICALLY EVIDENT OUTBREAK SETUP VIA
   A SHORTWAVE TROUGH/STRONG JET STREAK CURRENTLY NEARING THE
   LOWER-MIDDLE MS RIVER VALLEY PER SATELLITE IMAGERY...AN INCREASINGLY
   VOLATILE SETUP IS LIKELY THROUGH THE AFTERNOON. SUPERCELLS CAPABLE
   OF STRONG/VIOLENT TORNADOES ARE EXPECTED TO BECOME PREVALENT ACROSS
   AN INCREASINGLY UNSTABLE/WEAKLY CAPPED WARM SECTOR...WITH WSR-88D
   VWP OBSERVED AND RUC FORECASTS REFLECTING INCREASINGLY LONG/LOOPING
   LOW LEVEL HODOGRAPHS. IN THE WAKE OF A MORNING SEVERE MCS...THE
   AIRMASS IS EXPECTED TO RAPIDLY RECOVER ACROSS FAR NORTHERN AL INTO
   MIDDLE TN BY LATE AFTERNOON/EARLY EVENING.
   
   ..GUYER.. 04/27/2011
   
   
   ATTN...WFO...MRX...FFC...OHX...BMX...HUN...MOB...
   
   LAT...LON   31738724 31628828 33268819 35858732 34808504 31738724