MESOSCALE PRECIPITATION DISCUSSION 0183
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
401 PM EDT TUE MAY 22 2018

AREAS AFFECTED...SRN/ERN KENTUCKY...NRN TENNESSEE

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

VALID 222000Z - 230030Z

SUMMARY...SMALL LINES AND CLUSTERS OF STORMS WERE BEGINNING TO
SLOW DOWN AND MERGE...LEADING TO LOCALIZED AREAS OF VERY HEAVY
RAINFALL. RAIN RATES APPROACHING 2 IN/HR COULD LEAD TO FLASH
FLOODING.

DISCUSSION...REGIONAL RADARS IN THE PAST COUPLE HOURS HAVE SHOWN
BOTH SLIGHTLY SLOWER STORM MOTIONS AND A TENDENCY FOR CELL MERGERS
GIVEN SLIGHTLY CHAOTIC STORM MOTIONS. THIS WAS LEADING TO LARGER
AND MORE ORGANIZED CLUSTERS OF STORMS WITH A LONGER RESIDENCE TIME
IN SPECIFIC LOCATIONS...AND THUS INCREASING RAIN RATES. NWS RADAR
DUAL POL RAINFALL ESTIMATES WERE AS HIGH AS 2 IN/HR IN SOME AREAS.
THE CONVECTION APPEARED TO BE ORGANIZING JUST AHEAD OF A COLD
FRONT...WITH A COALESCING COLD POOL AND SOME MERGING CONVECTIVE
OUTFLOWS. THIS WAS GENERALLY LEADING TO AN E/SE PROGRESSION OF THE
CONVECTION WITH TIME...AND THIS GRADUAL PROGRESSION SHOULD
CONTINUE INTO THE EARLY EVENING HOURS.

HOWEVER...GIVEN THE RELATIVELY WEAK FLOW (WITH BACKBUILDING
CORFIDI VECTORS AROUND 5 KNOTS FROM A VARIETY OF DIRECTIONS) AND
WELL-DEFINED CONVECTIVE OUTFLOWS...CLUSTERS OF STORMS SHOULD
CONTINUE TO MEANDER AND OCCASIONALLY MERGE WITH OTHER CONVECTION.
THIS IS PARTICULARLY FAVORED OVER SOUTH-CENTRAL KENTUCKY INTO FAR
NORTHERN TENNESSEE...FROM BOWLING GREEN KY TO LONDON KY...AND THEN
SOUTH TO NEAR LIVINGSTON TN WHERE RADARS SHOW BOTH AN ABUNDANCE OF
CONVECTION AND ONGOING CELL MERGERS.

LAMERS

ATTN...WFO...JKL...LMK...MRX...OHX...PAH...RLX...

ATTN...RFC...LMRFC...OHRFC...

LAT...LON   38108398 38078267 37478257 36918295 36438376
            36098509 36108696 36638770 36918746 37248640
            37288556 37468482