MESOSCALE DISCUSSION 1630
NWS STORM PREDICTION CENTER NORMAN OK
1112 AM CDT MON JUL 12 2004
AREAS AFFECTED...ERN TN/SWRN NC/NRN AL/NWRN GA
CONCERNING...SEVERE THUNDERSTORM POTENTIAL
VALID 121612Z - 121845Z
SEVERE TSTM POTENTIAL WAS INCREASING ACROSS PARTS OF THE TN VALLEY
AND THE SOUTH. A SCATTERING OF DAMAGING WIND EVENTS MAY UNFOLD
ACROSS THESE AREAS THROUGH THIS AFTERNOON. RANDOM/PULSE NATURE OF
THE THREAT WILL MAKE IT DIFFICULT TO CONTAIN THE OVERALL HAZARD
WITHIN A TSTM WATCH BUT PARTS OF THE REGION WILL BE UPGRADED TO
HIGHER SEVERE WIND PROBABILITIES/SLGT RISK IN THE NEXT DAY 1
OUTLOOK.
TSTMS HAVE RECENTLY DEVELOPED ACROSS PARTS OF NERN AL WITHIN
MODERATELY UNSTABLE AIRMASS WHERE MLCAPE VALUES WERE APPROACHING
1500 J/KG. THIS REGION APPEARS TO BE UNDER THE INFLUENCE OF WEAK
BACKGROUND ASCENT ASSOCIATED WITH DIFFLUENT MID LEVEL FLOW IN THE
BASE OF A TROUGH CROSSING THE OH VALLEY. FURTHERMORE...WEAK
CAPPING...STRONG HEATING...AND ABUNDANT MOISTURE WILL PROMOTE
VIGOROUS UPDRAFTS DESPITE RELATIVELY WEAK MID LEVEL LAPSE RATES. MID
LEVEL DRY AIR INTRUSION AND SURFACE DEWPOINT DEPRESSIONS INCREASING
TO MORE THAN 20F SHOULD ALSO CONTRIBUTE TO A HIGHER CONCENTRATION OF
DAMAGING WET DOWNBURST WINDS AS THIS CONVECTION INTENSIFIES THROUGH
THE AFTERNOON. GIVEN WEAK 10-15KT MID LEVEL FLOW EXPECT THE BULK OF
THIS CONVECTION TO REMAIN PULSE IN NATURE. HOWEVER...THE REGION WILL
NEED TO BE MONITORED FOR FURTHER ORGANIZATION...AND POSSIBLY A MORE
WIDESPREAD WIND DAMAGE THREAT AS THE AFTERNOON PROGRESSES.
..CARBIN.. 07/12/2004
ATTN...WFO...GSP...MRX...FFC...OHX...BMX...HUN...
35758349 33468306 32538451 32508669 34658806