MESOSCALE PRECIPITATION DISCUSSION 0112
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
719 PM EDT MON APR 11 2016
AREAS AFFECTED…S MISSISSIPPI…SW ALABAMA
CONCERNING…HEAVY RAINFALL…FLASH FLOODING POSSIBLE
VALID 112320Z – 120400Z
SUMMARY…HVY RAINFALL ASSOCIATED WITH APPROACHING SQUALL LINE.
DISCUSSION…VIS/IR SATL AND RADAR MOSAIC SHOW WELL DEFINED MCS/SQUALL LINE MOVING SEWARD ACROSS CENTRAL MS AND EXTENDING UP
TOWARD BHM. BEST INSTABILITY AND MST FLUX/INFLOW TO THE COMPLEX IS ENHANCED ON THE SW EDGE TOWARD JAN ATTM WITH IR TOPS TO -75C
AND WITH MST AVAILABLE TO 1.75″ AND SBCAPES IN THE 500-1000 J/KG RANGE THROUGH THE LATE EVENING…CELLS WILL CONTINUE TO BE QUITE
EFFICIENT WITH RATES OF 1.5-2.0″/HR WITH NEARLY 1.5″ IN LESS THAN 20 MINUTES IN PART FOLLOWED BY A BROAD SHIELD OF MODERATE
PRECIPITATION BEHIND SUPPORTED BY THE ISENTROPIC ASCENT FROM SWLY FLOW ACROSS THE NW-SE OUTFLOW BOUNDARY ALONG THE WESTERN EDGE OF
THE MCS ITSELF. CANNOT RULE OUT ISOLATED CELLS FORMING AHEAD OF THE SQUALL LINE AS IT MOVES SOUTH…AND MERGING INCREASING THE
SHORT TERM FLASH FLOOD THREAT EVEN WITHIN INCREASINGLY HIGHER GUIDANCE VALUES NEARER THE COASTAL COUNTIES. THE THREAT OF MOST
EXTREME RATES REDUCES FURTHER EAST IN S AL…AWAY FROM INSTABILITY POOL OVER SE LA/SW MS AND BEST ASCENT/FORCING AS WELL…BUT
FLOODING THREAT IS NOT NEGLIABLE.
