MESOSCALE PRECIPITATION DISCUSSION 0237
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
649 PM EDT WED MAY 30 2018

AREAS AFFECTED...EAST CENTRAL MS INTO CENTRAL AL

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

VALID 302250Z - 310150Z

SUMMARY...SCATTERED CONVECTION MOVING OVER AREAS THAT RECEIVED
VERY HEAVY RAINFALL EARLIER TODAY COULD POSE A FLASH FLOOD THREAT
INTO THE EVENING HOURS.

DISCUSSION...SCATTERED CONVECTION IS FIRING AHEAD OF A WEAK SHORT
WAVE CROSSING WESTERN TN LATE THIS AFTERNOON. CLEAR SKIES IN THE
WAKE OF THE MORNING CONVECTION HAS ALLOWED INSTABILITY TO REBOUND
OVER EASTERN MS/WESTERN AL...WHERE MLCAPE VALUES HAVE REACHED 1500
J/KG. A LOW LEVEL SOUTH SOUTHWEST FLOW CONTINUES TO FEED DEEP
MOISTURE AHEAD OF THE CONVECTION...WITH PRECIPITABLE WATER VALUES
BETWEEN 1.75/2.00 INCHES OVER EASTERN MS.

WHILE THE CONVECTION IS SCATTERED...STORMS HAVE BEEN PRODUCING
HOURLY RAINFALL RATES BETWEEN 1.50 AND 2.00 INCHES OVER LEAKE
COUNTY MS IN THE DEEP MOISTURE IN PLACE. SINCE THE BEST SYNOPTIC
SCALE ASCENT IS CROSSING WESTERN TN WITH THE SHORT WAVE... IT IS
NOT CLEAR JUST HOW WIDESPREAD THE CONVECTION BECOMES MORE THE LOSS
OF DAY TIME HEATING CAUSES THE CONVECTIVE THREAT TO WANE.

THE MOST RECENT HRRR/EXPERIMENTAL HRRR KEEPS THE CURRENT ACTIVITY
MORE OR LESS INTACT AS IT APPROACHES CENTRAL AL... GENERALLY AFTER
31/00Z. AFTER THAT TIME...DUE TO LOSS OF HEATING...THE CONVECTION
IS EXPECTED TO DIMINISH IN COVERAGE AND INTENSITY. BEFORE THAT
TIME...THE HRRR/EXPERIMENTAL HRRR SHOWED LOCAL 2.00/3.00 INCH
RAINFALL AMOUNTS. THESE AMOUNTS SEEM PLAUSIBLE...GIVEN WHAT HAS
OCCURRED THUS FAR.

IF THESE RAINFALL RATES SURVIVE TO CENTRAL AL...THEY WOULD BE MORE
THAN SUFFICIENT O INITIATE ADDITIONAL FLASH FLOODING IN AREAS THAT
WERE HIT HARD THIS MORNING. HOWEVER...SINCE THERE IS SOME QUESTION
ABOUT WHETHER THE CONVECTION COULD SURVIVE UNTIL THEN...FLASH
FLOODING IS ONLY CONSIDERED POSSIBLE.

HAYES

ATTN...WFO...BMX...FFC...HUN...JAN...MEG...MOB...

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

LAT...LON   33938743 33798565 33138511 32518507 32088569
            31968651 31998721 31998727 32098853 32518953
            33708960