
MESOSCALE DISCUSSION 0120
NWS STORM PREDICTION CENTER NORMAN OK
1114 PM CST FRI FEB 21 2003
AREAS AFFECTED...PORTIONS NRN AL...MIDDLE/ERN TN...NWRN GA
CONCERNING...HEAVY RAINFALL
VALID 220514Z - 220915Z
HEAVY RAIN POTENTIAL IS FORECAST TO SHIFT GENERALLY NEWD ACROSS
NRN AL INTO NWRN GA THROUGH AT LEAST 8Z...WITH INCREASE IN PRECIP
RATES ACROSS MID/ERN TN. THIS HAZARD WILL INCLUDE STEEP TERRAIN
OF SRN-MOST APPALACHIAN REGION. RAIN RATES GENERALLY 1-2
INCHES/HOUR SHOULD BE COMMON...WITH LOCAL AMOUNTS 2.5-3
INCHES/HOUR POSSIBLE IN MOST INTENSE CORES.
MODIFIED RAOBS AND FORECAST SOUNDINGS SUGGEST 1.25-1.5 INCH PW
WILL BE COMMON...WITH INCREASING LOW-MIDDLE LEVEL MIXING RATIOS
AS MOISTURE ADVECTION AND TRANSPORT CONTINUES FROM NRN GULF. LOW
LEVEL WAA-RELATED ASCENT/DESTABILIZATION IS EXPECTED TO INCREASE
ACROSS THIS REGION AS UPPER VORTEX OVER SE TX MOVES NEARER. THIS
WILL LEAD TO DEVELOPMENT OF ELEVATED MUCAPE UP TO 800 J/KG AND
INCREASING COVERAGE OF TSTMS...WITH MERGING/TRAINING OF INTENSE
RAIN CORES INCREASINGLY PROBABLE. ALSO...ISENTROPIC LIFT SHOULD
STRENGTHEN AMIDST 50-70 KT LLJ.