MESOSCALE PRECIPITATION DISCUSSION 0245
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
540 PM EDT THU MAY 31 2018

AREAS AFFECTED...WESTERN KY...FAR SOUTHERN IL...SOUTHERN MO

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

VALID 312140Z - 010140Z

SUMMARY...CONVECTION TRAINING ALONG A LINE OF LOW LEVEL
CONVERGENCE IN A HIGH MOISTURE CONTENT AIRMASS COULD POSE A FLASH
FLOOD THREAT INTO THE EARLY EVENING HOURS.

DISCUSSION...REGIONAL RADARS HAVE INDICATED CONVECTION DEVELOPING
ALONG A LINE OF LOW LEVEL CONVERGENCE EXTENDING FROM CENTRAL KT
INTO SOUTHERN MO. THE GOES-16 CLEAN IR LOOP SHOWED COOLING TOPS
ALONG THIS LINE...IN A NARROW AXIS OF 1500-2000 J/KG OF MLCAPE.
THE LOW LEVEL CONVERGENCE IS FOCUSING 1.75 INCH PRECIPITABLE WATER
AIR (WHICH IS ABOUT TWO STANDARD DEVIATIONS ABOVE THE MEAN) IN THE
DEVELOPING CONVECTION.

WHILE THE CONVECTION IS STILL SCATTERED ALONG THE LOW LEVEL
AXIS...IT IS DRAWING ON THE DEEP MOISTURE IN PLACE TO PRODUCE
HOURLY RAINFALL RATES BETWEEN 1.50 AND 2.00 INCHES. A RECENT ASOS
REPORT NEAR KPAH SHOWED HOURLY RAINFALL RATES IN EXCESS OF 2.00
INCHES WITH THE STORMS. EARLIER CONVECTION MOVING THROUGH THIS
AREA MOISTENED THE SOILS OVER WESTERN KY...AND THE ADDITIONAL
RAINFALL COULD POSE A SHORT TERM FLASH FLOOD THREAT.

A SHORT WAVE CROSSING CENTRAL MO COULD ALLOW THE CONVECTION TO
BECOME BETTER ORGANIZED ALONG THE LOW LEVEL CONVERGENCE AXIS
THROUGH 01/00Z. THE 850-300 MB MEAN WIND SUGGESTS THAT THE
CONVECTION WOULD TRAVEL WEST TO EAST ALONG THE AXIS...AND THE
POTENTIAL FOR TRAINING WILL ENHANCE THE FLASH FLOOD THREAT.

THE MOST RECENT HRRR/EXPERIMENTAL HRRR INDICATED THE POTENTIAL FOR
LOCAL 2.00/3.00 INCHES OF RAINFALL...WITH THE HIGHEST AMOUNTS OVER
WESTERN KY. BASED ON WHAT HAS OCCURRED...THESE VALUES SEEM
PLAUSIBLE. THE FLASH FLOOD THREAT IS HIGHER ACROSS WESTERN
KY...DUE TO ANTECEDENT CONDITIONS. FURTHER WEST INTO SOUTHERN
MO...IT IS NOT CLEAR HOW MUCH MORE WIDESPREAD THE CONVECTION
BECOMES ALONG THE LINE. BECAUSE OF THIS...FLASH FLOODING IS ONLY
CONSIDERED POSSIBLE.

HAYES

ATTN...WFO...LMK...LSX...LZK...MEG...OHX...PAH...SGF...

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

LAT...LON   37538643 36648679 36518817 36468938 36459206
            36719320 37129330 37339169