MESOSCALE PRECIPITATION DISCUSSION 0746
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1037 PM EDT WED OCT 19 2016
 
AREAS AFFECTED...SOUTHERN IN...SOUTHERN ILL...NORTHERN
KY...SOUTHERN OHIO 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 200236Z - 200636Z
 
SUMMARY...DEEP MOISTURE AND INSTABILITY WITHIN A NARROW CORRIDOR
SUPPORTS SOME TRAINING CONVECTION WITH POSSIBLE FLASH FLOODING
CONDITIONS GOING INTO THE EARLY OVERNIGHT HOURS. 

DISCUSSION...A STATIONARY FRONTAL ZONE DRAPED ACROSS THE OHIO
VALLEY LATE WEDNESDAY EVENING, ALONG WITH DEEP BOUNDARY LAYER
MOISTURE CONVERGENCE AND UPPER LEVEL DIVERGENCE, WILL CONTINUE TO
SUPPORT MULTIPLE ROUNDS OF HEAVY CONVECTION THROUGH 630Z.  RIGHT
ENTRANCE JET DYNAMICS INTENSIFY AS UPSTREAM ENERGY OVER THE
MIDWEST STATES STRENGTHENS THE JET OVERNIGHT AND FURTHER ENHANCES
ASCENT.  THE LATEST RAP MODEL ANALYSIS CONTINUES TO INDICATE A
MOIST ENVIRONMENT WITH PWS ON THE ORDER OF 1.4 TO 1.8 INCHES FROM
SOUTHERN ILLINOIS TO THE GREATER CINCINNATI AREA.  MUCAPES OF 1500
TO 2000 J/KG IN THE WARM SECTOR PER THE LATEST SPC MESOANALYSIS
ARE SUFFICIENT FOR SOLID UPDRAFTS AND EFFICIENT RAINFALL
GENERATION.  

THE LATEST HI-RES MODEL GUIDANCE SUPPORTS THE IDEA OF ADDITIONAL
RAINFALL AMOUNTS ON THE ORDER OF 1 TO 3 INCHES THROUGH 630Z, WITH
ISOLATED AMOUNTS OF 4 INCHES POSSIBLE.  THE HRRR AND HRRR
EXPERIMENTAL SHOW A NARROW CORRIDOR OF HEAVY RAINFALL EXTENDING
FROM SOUTHERN INDIANA TO SOUTH-CENTRAL OHIO.  OTHER MODEL
SOLUTIONS, SUCH AS THE ARW AND NMMB ARE MORE CONSERVATIVE WITH
AMOUNTS.  GIVEN THE ONGOING HEAVY CONVECTION, IT SEEMS THAT THE
HRRR MODELS HAVE A BETTER HANDLE ON THE QPF.

THE MAIN LIMITING FACTOR WITH RESPECT TO FLASH FLOODING ARE THE
DRY ANTECEDENT CONDITIONS OVER THIS REGION.  FLASH FLOOD GUIDANCE
VALUES RANGE FROM 2-2.5 INCHES PER HR, AND 2.5-3" PER 3HR.  THOUGH
CONDITIONS ARE FAVORABLE FOR TRAINING AND HIGHER RATES GIVEN THE
OVERALL ATMOSPHERIC SETUP, THE FLASH FLOOD THREAT SHOULD BE
LIMITED IN COVERAGE UNLESS CELLS SET UP REPEATEDLY OVER FLASH
FLOOD PRONE AREAS SUCH AS URBAN CENTERS AND STEEP RIVER VALLEYS.

HAMRICK

ATTN...WFO...CLE...ILN...ILX...IND...LMK...LSX...PAH...PBZ...
RLX...

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

LAT...LON   40488231 40248096 39428103 38918209 38548394 
            38118561 37828735 37878853 38788885 39488774 
            39888599 40228422