MESOSCALE PRECIPITATION DISCUSSION 0265
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
947 AM EDT TUE MAY 23 2017

AREAS AFFECTED...CENTRAL AND SOUTHERN AL...CENTRAL AND NORTHERN GA

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 231236Z - 231701Z

SUMMARY...EMBEDDED CONVECTION WILL CONTINUE WITHIN A BROAD RAIN
SHIELD EXTENDING FROM CENTRAL AND SOUTHERN AL ACROSS CENTRAL AND
NORTHERN GA. LOCAL HOURLY RAINFALL RATES EXCEEDING 1" FOR THE NEXT
SEVERAL HOURS AND RAINFALL TOTALS LOCALLY EXCEEDING 3" WILL RESULT
IN A CONTINUED THREAT FOR AREAS OF FLASH FLOODING DURING THE NEXT
SEVERAL HOURS.

DISCUSSION...RADAR SHOWS THAT HOURLY RAIN RATES CONTINUE TO
LOCALLY EXCEED 1" ACROSS CENTRAL AND SOUTHERN AL INTO CENTRAL AND
NORTHERN GA. MUCAPE VALUES ARE AROUND 2000-3000 J/KG...WHILE
STRONG LOW LEVEL SOUTHERLY FLOW IS TRANSPORTING VERY MOIST AIR --
PRECIPITABLE WATER VALUES ARE 1.5-2" -- ACROSS A STATIONARY
FRONTAL BOUNDARY ACROSS THE REGION.

THESE CONDITIONS SHOULD PERSIST FOR THE NEXT SEVERAL HOURS AT
LEAST...AND BULK SHEAR OF 25-45 KT AND INCREASED INSTABILITY DUE
TO DAYTIME HEATING SUGGEST THAT CONVECTION COULD BECOME MORE
ORGANIZED. IN ADDITION A WESTERLY JET ACROSS THE TX AND LA GULF
COASTS AND SOUTHWESTERLY JET ALONG THE TN VALLEY SHOULD RESULT IN
CONTINUING DIFFLUENCE ALOFT.

RECENT RUNS OF THE HRRR PLUS THE RAP AND THE NAM SUPPORT RAINFALL
TOTALS LOCALLY EXCEEDING 3" ACROSS THE REGION THROUGH 18Z. SO THE
THREAT FOR AREAS OF FLASH FLOODING WILL CONTINUE. 

MCDONNAL

ATTN...WFO...BMX...CAE...FFC...GSP...MOB...TAE...

ATTN...RFC...SERFC...

LAT...LON   34578361 34288301 33908261 33108211 33108211
            32808246 32048418 31088715 32008805 32928665
            34028489 34278448