MESOSCALE PRECIPITATION DISCUSSION 0249
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1145 PM EDT THU MAY 31 2018

AREAS AFFECTED...SRN IL INTO SRN IN AND FAR NRN KY

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

VALID 010341Z - 010815Z

SUMMARY...TRAINING CONVECTION OVER SOUTHERN IL...SOUTHERN IN INTO
FAR NORTHERN KY MAY PRODUCE FLASH FLOODING WITH AN ADDITIONAL 2-4
INCHES OF RAIN EXPECTED THROUGH 08Z.

DISCUSSION...AT 0315Z...KVWX RADAR IMAGERY SHOWED REPEATING ROUNDS
OF SOMEWHAT DISORGANIZED CONVECTION IN THE VICINITY OF I-64 FROM
SOUTHERN IL INTO SOUTHERN IN. PERIODS OF EMBEDDED WEST TO EAST
TRAINING SHOWED RECENT RADAR ESTIMATED RAINFALL RATES NEAR 2 IN/HR
OVER PERRY...FRANKLIN AND HAMILTON COUNTIES. THE CONVECTION IS
OCCURRING AHEAD OF AN 850 MB COLD FRONT WHICH EXTENDED FROM
NORTHWESTERN OH INTO SOUTHERN MO...WITH THE SPC MESOANALYSIS
SHOWING MUCAPE OF 500-1000 J/KG AVAILABLE OVER THE REGION. AREA
VAD WIND PLOTS SHOWED WEST-SOUTHWESTERLY 850-700 MB WINDS OF
ROUGHLY 30 KT AHEAD OF THE BOUNDARY WHICH WAS NEAR OBSERVED ECHO
MOVEMENT.

A LOCAL MAX IN AVAILABLE MOISTURE...REPRESENTED BY PRECIPITABLE
WATER VALUES OF 1.6 TO 2.0 INCHES IN GPS SITE OBSERVATIONS AND RAP
ANALYSES...EXTENDED JUST AHEAD OF THE 850 MB FRONT FROM SOUTHERN
MO INTO THE OHIO VALLEY. ALOFT...FLOW IS DIFFLUENT AHEAD OF THE
RELATED UPPER TROUGH AXIS WITH A FOCUS LOCATED NEAR THE OHIO
RIVER. THE 850 MB FRONT IS EXPECTED TO CONTINUE A SLOW BUT STEADY
MOVEMENT OFF TO THE SOUTH AND EAST OVER THE NEXT FEW HOURS WHICH
SHOULD END ANY HEAVY RAIN/FLASH FLOOD THREAT FROM NORTHWEST TO
SOUTHEAST...BUT AHEAD OF THE BOUNDARY WILL BE THE POTENTIAL FOR
ADDITIONAL TRAINING WITH RAINFALL RATES OF 1-2 IN/HR. 3 HOUR FLASH
FLOOD GUIDANCE VALUES ARE GENERALLY 1.5 TO 2.5 INCHES WHICH MAY BE
EXCEEDED IN A FEW LOCATIONS WITH STORM TOTAL ADDITIONAL RAINFALL
OF 2-4 INCHES EXPECTED THROUGH 08Z.

OTTO

ATTN...WFO...ILX...IND...LMK...LSX...PAH...

ATTN...RFC...NCRFC...OHRFC...

LAT...LON   38788730 38778606 38498541 37858537 37628623
            37608769 37748925 38128952 38438909 38658807