MESOSCALE PRECIPITATION DISCUSSION 0493
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
239 PM EDT TUE JUL 26 2016
 
AREAS AFFECTED...EASTERN OHIO VALLEY 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 261837Z - 262301Z
 
SUMMARY...INCREASED STORM COVERAGE IN A HIGHLY EFFICIENT RAINFALL
ENVIRONMENT MAY LEAD TO ISOLATED FLASH FLOODING...

DISCUSSION...RECENT TRENDS SHOW AN UPTICK IN CONVECTION ACROSS
PORTIONS OF FAR NORTHERN KENTUCKY...SOUTEHRN OHIO AND PORTIONS OF
WEST VIRGINA. WHILE THERE IS A LOW LEVEL BOUNDARY IN THE
VICINITY...INFLOW AND CONVERGENCE REMAINS WEAK. HOWEVER DIURNAL
HEATING AND SYNOPTIC ASCENT AHEAD OF SHORTWAVE/MCV EVIDENT ON
VISIBLE SATELLITE OVER IL...HAVE BEEN ENOUGH TO SUPPORT INCREASED
CONVECTIVE COVERAGE. DEEP LAYER SHEAR AROUND 20 KTS IS ALSO
SUPPORTIVE OF LOOSELY ORGANIZED MULTI CELL STRUCTURES.

STORM MOTIONS OFF TO THE EAST AT 15-20 KTS SHOULD GENERALLY LIMIT
THE OVERALL FLASH FLOOD THREAT. HOWEVER CONTINUED INCREASED STORM
COVERAGE WILL LIKELY LEAD TO AT LEAST A FEW CELL MERGERS AND
TRAINING AS THE CONVECTION MOVES OFF TO THE EAST. STORMS SHOULD BE
EFFICIENT RAINFALL PRODUCERS GIVEN DEEP WARM CLOUD DEPTHS AND HIGH
PRECIPITABLE WATER VALUES. IN FACT RECENT GPS OBS SHOW
PRECIPITABLE WATER AROUND 2.2" ACROSS SOUTHERN OHIO AND
VICINITY...WHICH IS AROUND THE RECORD HIGH VALUE. NORMALLY WOULD
NOT EXPECT A FLASH FLOOD THREAT FROM A SETUP LIKE THIS...HOWEVER
THE NEAR RECORD PWAT VALUES SUGGEST THAT A MARGINAL FLASH FLOOD
THREAT MAY EXIST. AS THE COMBINATION OF INCREASED STORM COVERAGE
AND HIGH PWAT VALUES SHOULD LEAD TO ISOLATED RAINFALL AMOUNTS OF
3-4" IN A FEW HOURS...WHICH MAY BEGIN TO LOCALLY EXCEED FLASH
FLOOD GUIDANCE. THE HRRR AND PARALLEL HRRR APPEAR TO NOW HAVE A
DECENT HANDLE ON THIS CONVECTION.

CHENARD

ATTN...WFO...ILN...JKL...LMK...RLX...

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

LAT...LON   39488203 39198064 38728044 38088121 38068286 
            38328491 38378512 38548544 39148425 39378327