MESOSCALE DISCUSSION 0999

MESOSCALE DISCUSSION 0999
NWS STORM PREDICTION CENTER NORMAN OK
0521 PM CDT THU MAY 31 2012

AREAS AFFECTED...PORTIONS OF WRN AND SRN AL AND THE WRN FL PANHANDLE

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 312221Z - 312345Z

PROBABILITY OF WATCH ISSUANCE...60 PERCENT

SUMMARY...SEVERE THREAT INCREASING FOR PARTS OF WRN/SRN AL AND FAR
WRN FL PANHANDLE. A SEVERE THUNDERSTORM WATCH MAY BE NEEDED IN THE
NEXT HOUR OR SO. MAIN THREAT WILL BE STRONG/LOCALLY DAMAGING WINDS
INTO THE EARLY EVENING.

DISCUSSION...SEVERE LINE OF STORMS ACROSS ERN MS WILL CONTINUE TO
TRACK EWD TOWARD PORTIONS OF WRN AND CNTRL AL LATE THIS AFTERNOON.
THE DOWNSTREAM AIR MASS WILL REMAIN FAVORABLE FOR CONTINUED SEVERE
STORMS CAPABLE OF STRONG/SEVERE WIND GUSTS FOR AT LEAST ANOTHER FEW
OF HOURS. WHILE DEEP LAYER SHEAR IS NOT STRONG /LESS THAN 25 KT/ IT
IS SUFFICIENT TO SUSTAIN ORGANIZED CONVECTION. ADDITIONALLY...STEEP
LOW LEVEL LAPSE RATES WILL AID IN DAMAGING WIND POTENTIAL. THERE IS
SOME UNCERTAINTY AS TO HOW FAR NORTH/EAST THE SEVERE THREAT MAY
PROGRESS DUE TO DRIER AIR MASS ACROSS PORTIONS OF NERN AND ERN
AL...WHICH WILL LIKELY LIMIT SEVERE POTENTIAL AS INSTABILITY BECOMES
MUCH WEAKER. ALSO...WITH THE LOSS OF DAYTIME HEATING THE BOUNDARY
LAYER WILL BEGIN TO STABILIZE FURTHER EAST AS THE STORMS PROGRESS
INTO THE ALREADY LESS FAVORABLE AIR MASS. THEREFORE...A SMALL SEVERE
WATCH MAY BE NEEDED TO COVER PORTIONS OF W-CNTRL/SRN AL INTO THE FAR
WRN FL PANHANDLE FOR A FEW HOURS INTO THE EARLY EVENING.

..LEITMAN/CORFIDI.. 05/31/2012


ATTN...WFO...TAE...BMX...MOB...LIX...