MESOSCALE DISCUSSION 0821

MESOSCALE DISCUSSION 0821
NWS STORM PREDICTION CENTER NORMAN OK
1213 PM CDT THU MAY 08 2008

AREAS AFFECTED...E CNTRL MS INTO W CNTRL AL

CONCERNING...TORNADO WATCH 277...

VALID 081713Z - 081845Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 277 CONTINUES.

AN ADDITIONAL WW PROBABLY WILL BE NEEDED EARLY THIS AFTERNOON.

CONVECTIVE CELLS CONTINUE TO SLOWLY DEEPEN ACROSS SOUTHWEST THROUGH
EAST CENTRAL MISSISSIPPI...ALONG/JUST AHEAD OF THE SOUTHERN FLANK OF
ONGOING SQUALL LINE NOW ADVANCING TOWARD THE UPPER TENNESSEE VALLEY.
THE BOUNDARY LAYER INSTABILITY IS STILL RATHER MODEST... ON THE
ORDER OF 1000 J/KG...AND THIS...COUPLED WITH SUBSIDENCE WARMING
ALOFT...IS SLOWING STORM INTENSIFICATION. LATEST RUC GUIDANCE NOW
SUGGESTS THAT INHIBITION FOR BOUNDARY LAYER PARCELS IS SMALL ACROSS
MUCH OF CENTRAL/SOUTHERN MISSISSIPPI AND ALABAMA. BUT...POTENTIAL
FOR VIGOROUS STORM INITIATION SEEMS MOST PROBABLE ACROSS EAST
CENTRAL MISSISSIPPI INTO CENTRAL ALABAMA...WHERE MID-LEVEL
TEMPERATURES REMAIN COOLER ASSOCIATED WITH LINGERING INFLUENCE OF
UPPER IMPULSE NOW LIFTING THROUGH KENTUCKY/TENNESSEE. THIS STILL
APPEARS POSSIBLE NEAR/NORTH OF MERIDIAN INTO AREAS NEAR/SOUTH OF
TUSCALOOSA/BIRMINGHAM BY 18-19Z. AND...WITHIN THE PRESENCE OF
STRONG DEEP LAYER SHEAR AND LARGE CLOCKWISE CURVED LOW-LEVEL
HODOGRAPHS NEAR A 40-50 KT LOW-LEVEL JET AXIS...THE RISK FOR
DISCRETE SUPERCELLS WITH TORNADOES WILL INCREASE. ISOLATED STRONG
TORNADOES ARE POSSIBLE.