MESOSCALE PRECIPITATION DISCUSSION 0272
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
400 PM EDT FRI JUN 08 2018

AREAS AFFECTED...EAST-CENTRAL IN...OH...WEST-CENTRAL WV

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

VALID 082000Z - 090100Z

SUMMARY...CLUSTERS OF HEAVY SHOWERS AND THUNDERSTORMS WITH SOME
BACKBUILDING AND LOCALIZED REPEATING OF CELLS IS EXPECTED THROUGH
THE REMAINDER OF THE AFTERNOON AND EARLY EVENING. SOME FLASH
FLOODING WILL BE POSSIBLE.

DISCUSSION...THE LATEST RADAR IMAGERY IS SHOWING SEVERAL CLUSTERS
OF SHOWERS AND THUNDERSTORMS DEVELOPING AND GRADUALLY BECOMING
BETTER ORGANIZED OVER ESPECIALLY CENTRAL OH. THE ACTIVITY IS
FOCUSED NEAR AND TO THE SOUTH OF A QUASI-STATIONARY FRONT...AND IS
BECOMING EMBEDDED WITHIN A MODERATELY UNSTABLE AIRMASS WITH MLCAPE
VALUES OF 1500 TO 2000 J/KG NOTED AS PER THE LATEST RAP ANALYSIS.

OVERALL THE MAIN SUPPORT FOR CONVECTION APPEARS TO BE TIED INTO
THE ALIGNMENT OF DIURNALLY ENHANCED INSTABILITY WITH THE FRONT
WHERE LOW LEVEL CONVERGENCE IS RELATIVELY ENHANCED.
HOWEVER...THERE IS EVIDENCE IN THE LATEST GOES-16 WV/IR IMAGERY OF
A MODEST MID/UPPER LEVEL JET STREAK CUTTING ACROSS THE OH VALLEY
WHICH IS ALSO DEPICTED IN THE 18Z RAP ANALYSIS. THIS MODEST ENERGY
ALOFT...MAINLY AROUND 300 MB...WILL BE SUFFICIENT TO DRIVE SOME
WEAK LEFT-EXIT REGION FORCING THAT SHOULD TEND TO PROMOTE SOME
ADDITIONAL CONVECTIVE EXPANSION/ORGANIZATION OVER THE NEXT COUPLE
OF HOURS AND ESPECIALLY WITH PEAK DIURNAL HEATING APPROACHING. AS
THIS OCCURS...ONE OTHER FACTOR TO CONSIDER WILL BE THE UNSTABLE
AND MOIST UPSTREAM LOW LEVEL SOUTHWEST FLOW THAT WILL BE
OVERRUNNING AN INCREASINGLY WELL-DEFINED COLD POOL. THIS WILL
PROMOTE SOME LOCALIZED BACKBUILDING AND REPEATING OF CELLS AS
CONVECTION REGENERATES NEAR THE EDGE OF THE COLD POOL.

PWATS ARE GENERALLY NEAR 1.5 INCHES...WHICH WILL BE CONDUCIVE FOR
HEAVY RAINFALL RATES. IN FACT...DUAL-POL RADAR ESTIMATES ARE
ALREADY AS MUCH AS 2 TO 3 INCHES/HR WHICH IS IN MOST CASES
EXCEEDING FFG VALUES.

EXPECT AS MUCH AS 3 TO 4 INCHES OF RAIN GIVEN THE SET-UP WITH
ISOLATED HEAVIER TOTALS. FLASH FLOODING WILL BE POSSIBLE AS A
RESULT GIVEN THESE TOTALS. CONVECTION SHOULD WEAKEN NEAR AND AFTER
00Z AS INSTABILITY BECOMES EXHAUSTED...SO THIS IS A SHORT-TERM
FLASH FLOOD CONCERN.

ORRISON

ATTN...WFO...CLE...ILN...IND...IWX...PBZ...RLX...

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

LAT...LON   41458325 40768159 39908096 39198102 38848150
            38588247 38738382 39358522 39788572 40258556
            40458464 41178428