MESOSCALE PRECIPITATION DISCUSSION 0016
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
425 AM EST THU JAN 12 2017
 
AREAS AFFECTED...NORTHERN AND CENTRAL OH...WESTERN PA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 120930Z - 121530Z
 
SUMMARY...TRAINING OF LOW TOPPED CONVECTION OVER AREAS WITH
RELATIVELY LOW FLASH FLOOD GUIDANCE COULD RESULT IN A FLASH FLOOD
THREAT THROUGH THE MID MORNING HOURS. 

DISCUSSION...LOW TOPPED CONVECTION AHEAD OF A COLD FRONT EXTENDING
FROM SOUTHEAST MI INTO SOUTHERN IL HAS BEGUN TO BECOME
REINVIGORATED WITH THE APPROACH OF A SHORT WAVE APPROACHING
NORTHWEST MO. THE CONVECTION IS REFORMING IN AN AXIS OF 250-500
J/KG OF MUCAPE...WHERE PRECIPITABLE WATER VALUES WERE NEARING 1.20
INCHES (PER THE LATEST RAP ANALYSIS). THE KIND RADAR SHOWED HOURLY
RAINFALL RATES NEAR 0.75 INCHES ACROSS NORTH CENTRAL IN. 

THE LATEST RAP SHOWS THE ELEVATED INSTABILITY PEAKING AGAIN IN THE
11Z TO 14Z TIME FRAME...AS MUCAPE VALUES TOP OUT OVER 500 J/KG.
THE BEST AXIS OF INSTABILITY IS EXPECTED TO BE COINCIDENT WITH A
SURGE OF 1.25 INCH PRECIPITABLE WATER AIR (WHICH IS CLOSE TO THREE
STANDARD DEVIATIONS ABOVE THE MEAN) ON THE NOSE OF A 65 KNOT LOW
LEVEL JET PUNCHING INTO CENTRAL OH. THE COMBINATION OF MOISTURE
AND INSTABILITY IS EXPECTED TO FUEL LOW TOPPED CONVECTION FROM
EAST CENTRAL IN ACROSS NORTH CENTRAL OH IN A PORTION OF WESTERN PA.

A WAVE FORMING ON THE FRONT ACROSS CENTRAL IN NEAR 12Z WILL SLOW
THE SOUTHEAST PROGRESS OF THE FRONT...AS IT BECOMES MORE PARALLEL
TO THE MID LEVEL FLOW. CORFIDI VECTORS BECOME BETTER ALIGNED WITH
THE 850-300 MB MEAN FLOW...WHICH COULD SUPPORT A GREATER THREAT OF
TRAINING. 

THE LATEST HRRR/00Z NSSL WRF HAD A STRONG SIGNAL THAT SUPPORTS THE
IDEA OF LOCAL 2.00+ INCH RAINFALL AMOUNTS STRETCHING FROM NORTH
CENTRAL OH INTO WESTERN PA. THREE HOUR FLASH FLOOD GUIDANCE VALUES
ARE AS LOW AS 1.00 TO 1.50 INCHES ACROSS PORTIONS OF THIS AXIS.
THEREFORE... TRAINING CONVECTION COULD RESULT IN A FLASH FLOOD
THREAT THROUGH THE MID MORNING HOURS IN LOCATIONS WITH LOWER FLASH
FLOOD GUIDANCE VALUES. 

HAYES

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

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

LAT...LON   41838038 41707947 41257943 40867984 40618068 
            40128347 40088431 40168486 40538488 41518199