MESOSCALE DISCUSSION 2147
   NWS STORM PREDICTION CENTER NORMAN OK
   1011 AM CDT SUN AUG 24 2008
   
   AREAS AFFECTED...PORTIONS AL...EXTREME SWRN GA.
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 241511Z - 241715Z
   
   BRIEF/SPORADIC SUPERCELLS MAY DEVELOP WITH OUTER BANDS REVOLVING
   AROUND REMAINS OF TS FAY.  TORNADO POTENTIAL IS WEAK/MRGL ATTM BUT
   MAY INCREASE THROUGH MID-LATE AFTERNOON.
   
   SFC ANALYSIS SHOWS DIFFUSE LOW OVER SERN MS BETWEEN PIB-MEI...WITH
   WEAK CENTRAL WINDS AND FILLING PRESSURE AS CIRCULATION OF FAY
   CONTINUES TO WEAKEN.  LOW-MIDLEVEL REMAINS OF TS FAY HAVE BECOME
   INTERMINGLED WITH PRE-EXISTING MID-UPPER LEVEL LOW THAT PIVOTED
   SWD/SEWD ACROSS AR AND LA YESTERDAY AFTERNOON AND OVERNIGHT. 
   MOISTURE CHANNEL IMAGERY AND 12Z BMX/TLH RAOBS INDICATE PRONOUNCED
   DRYING ALOFT FROM THAT UPPER PERTURBATION NOW WRAPPING AROUND ERN
   PORTION OF COMBINED CIRCULATION.  STRONGEST DRYING APPEARS CLOSER TO
   CENTER AS ALSO EVIDENT IN GPS PW DATA...WHICH SHOWS VALUES OF
   1.7-1.8 INCH FROM MOUTH OF MS RIVER NEWD ACROSS MOB AREA THEN NWD
   INTO CENTRAL AL...AND PRONOUNCED DROP IN PW LAST FEW HOURS BETWEEN
   MOB-BHM.  RELATIVELY MOIST LOW LEVEL PLUME IS EVIDENT FARTHER E
   ACROSS ERN AL...WRN GA AND FL PANHANDLE...WHICH SHOULD SUPPORT 
   CONVECTION POTENTIAL AS IT SHIFTS SLOWLY WWD IN STEP WITH
   TRANSLATIONAL MOTION OF BROADER CIRCULATION.  WHILE DRY SLOT REDUCED
   POTENTIAL CONVECTIVE COVERAGE CLOSER TO CENTER...IT IS SUPPORTING
   CONSIDERABLE BREAKS IN CLOUDS ACROSS MUCH OF SRN/CENTRAL AL THAT
   EXTEND EWD OVER BOUNDARY LAYER MOISTURE PLUME.  CONTINUED INSOLATION
   IN BETWEEN EXISTING CONVECTIVE BANDS MAY OFFSET VERY WEAK MID-UPPER
   LEVEL LAPSE RATES ENOUGH TO DEVELOP MLCAPE 250-500 J/KG OVER
   PORTIONS CENTRAL AL DURING NEXT FEW HOURS...INCREASING TO 1000 J/KG
   NEAR SRN PORTION AL/GA LINE.  STRENGTHENING INSTABILITY WILL
   COINCIDE WITH WEAKENING OF LOW LEVEL SHEAR...A TREND ALREADY EVIDENT
   IN DECREASE OF SELY NOCTURNAL LLJ FROM VWP SITES OVER SERN AND
   CENTRAL AL.  HOWEVER...FCST SOUNDINGS SUGGEST HODOGRAPH SIZE STILL
   WILL BE SUFFICIENT TO SUPPORT SUPERCELLS...ESPECIALLY FROM E-CENTRAL
   AL NWWD ACROSS CENTRAL AL WHERE SFC FLOW IS MOST STRONGLY
   BACKED...WITH 0-1 KM SRH 200-400 J/KG PERSISTING INTO AT LEAST
   MID-AFTERNOON.
   
   ..EDWARDS.. 08/24/2008
   
   
   ATTN...WFO...FFC...TAE...BMX...HUN...MOB...
   
   31438652 31948680 32588715 33308808 33668821 34148763
   33908654 33548552 32768485 31848483 31238490 31088556
   31188638