MESOSCALE PRECIPITATION DISCUSSION 0295
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
229 PM EDT TUE JUN 12 2018

AREAS AFFECTED...PORTIONS OF THE LOWER OHIO VALLEY

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

VALID 121828Z - 122345Z

SUMMARY...THUNDERSTORMS CAPABLE OF 1.5 TO 2.5 IN/HR RATES ARE
EXPECTED TO GROW IN COVERAGE ALONG THE LOWER OHIO RIVER
VALLEY...WITH POSSIBLE FLASH FLOODING ESPECIALLY IF OVERLAP OCCURS
WITH VERY LOW FLASH FLOOD GUIDANCE VALUES OVER SOUTHEASTERN IL
INTO SOUTHWESTERN IN. 2-3 INCHES WILL BE POSSIBLE THROUGH 00Z.

DISCUSSION...18Z SURFACE OBSERVATIONS PLACED AN OUTFLOW BOUNDARY
DUE TO MORNING CONVECTION FROM WEST-CENTRAL KY INTO SOUTH-CENTRAL
IL. VISIBLE IMAGERY ALSO SHOWED A WELL DEFINED MCV TRACKING
SOUTHEASTWARD FROM THE CENTRAL MO/IL BORDER WHICH IS EXPECTED TO
CONTINUE A SOUTHEASTWARD MOVEMENT THROUGH THE AFTERNOON.
CONVECTION WAS ALREADY DEVELOPING AHEAD OF THE MCV...BUT WAS
WEAKER TO THE NORTH OF THE OUTFLOW BOUNDARY WHERE THE ENVIRONMENT
IS LIKELY STILL CAPPED DUE TO COOLER SURFACE
TEMPERATURES...COMPARED TO LOCATIONS SOUTH OF THE OUTFLOW BOUNDARY
ALONG THE SOUTHERN MO/IL BORDER WHERE CONVECTION WAS MORE ROBUST.
RAP SOUNDINGS INDICATED LOCATIONS NORTH OF THE OUTFLOW WILL REACH
THEIR CONVECTIVE TEMPERATURE BETWEEN 86-88 F...WHICH APPEARS
POSSIBLE GIVEN BREAKS IN CLOUD COVER OVER SOUTHERN IL/IN.

GPS MEASUREMENTS INDICATED PRECIPITABLE WATER VALUES BETWEEN
1.6-1.8 INCHES AND MLCAPE WAS ESTIMATED TO BE BETWEEN 500-1500
J/KG ACROSS THE REGION...SLIGHTLY LOWER THAN RAP/HRRR ESTIMATES.
AREA VAD WIND PLOTS AND RAP ANALYSES DEPICTED AN AREA OF ENHANCED
SOUTHWESTERLY 850 MB FLOW (20-30 KT) FROM SOUTHERN IL INTO
SOUTHERN IN...WHICH SHOULD MOVE OFF TOWARD THE EAST AHEAD OF THE
MCV/MID-LEVEL WAVE. BRIEF TRAINING WITHIN THIS CORRIDOR OF
STRONGER 850 MB FLOW IS LIKELY TO SUPPORT RAINFALL RATES OF 1.5 TO
2.5 IN/HR...ALONG AND SOUTH OF THE OUTFLOW BOUNDARY...BUT SOME
OVERLAP TO THE NORTH WHERE FFG IS VERY LOW (0.75 INCHES IN 3
HOURS) WILL BE POSSIBLE. 2-3 INCHES OF RAINFALL IS EXPECTED FOR
THE 6 HOUR PERIOD ENDING 00Z.

OTTO

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

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

LAT...LON   38978827 38958750 38898728 38578678 38128645
            37528653 36988715 36678809 36528938 37138992
            37998967 38498908