MESOSCALE PRECIPITATION DISCUSSION 0352
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
309 AM EDT WED JUN 15 2016
 
AREAS AFFECTED...NORTHERN IL...NORTHWEST IN 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 150715Z - 151000Z
 
SUMMARY...ONGOING CONVECTION FED BY AN AXIS OF INSTABILITY AND
HIGH MOISTURE CONTENT AIR WILL POSE A SHORT TERM FLASH FLOOD
THREAT THROUGH THE EARLY MORNING HOURS.

DISCUSSION...REGIONAL RADARS SHOWED THE LINE OF CONVECTION
STRETCHING FROM NORTHEAST TO CENTRAL IL...AHEAD OF AN AXIS OF 500
TO 1000 J/KG OF MLCAPE AND NEARLY 2.00 INCH PRECIPITABLE WATER AIR
(WHICH IS BETWEEN TWO AND THREE STANDARD DEVIATIONS ABOVE THE
MEAN). HOURLY RAINFALL RATES ON THE KLOT RADAR WERE CLOSE TO 1.50
INCHES...BUT MESONET OBSERVATIONS WERE LOWER THAN THIS. THE
DISCREPANCY MAY BE DUE TO HAIL CONTAMINATION...AS HAIL HAS BEEN
REPORTED RECENTLY WITH THE CONVECTION.

WHILE THE NORTHERN PART OF THE LINE IS ACCELERATING AND MAINLY
OUTFLOW DOMINATED...THE PART OF THE CONVECTION LINE OVER CENTRAL
IL MAY BE SLOWING...AS IT BECOMES BETTER ALIGNED WITH THE MID
LEVEL WIND. THE ALIGNMENT COULD RESULT IN TRAINING...WHICH COULD
LEAD TO A SHORT TERM FLASH FLOOD THREAT. THE THREAT COULD PERSIST
INTO PORTIONS OF NORTHWEST IN... THOUGH FLASH FLOOD GUIDANCE
VALUES ARE HIGHER HERE THAN NORTHEAST AND CENTRAL IL. 

THE LATEST HRRR AND EXPERIMENTAL HRRR SUGGEST LOCAL 1-2 INCH
RAINFALL AMOUNTS ARE POSSIBLE THROUGH 10Z. LOCALLY HIGHER AMOUNTS
ARE POSSIBLE OVER PORTIONS OF NORTHERN IL...WHERE TRAINING COULD
BECOME AN ISSUE. THE THREAT SHOULD WANE TOWARD 10Z...AS THE
AVAILABLE INSTABILITY BECOMES EXHAUSTED.

HAYES

ATTN...WFO...DVN...ILX...IND...IWX...LOT...

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

LAT...LON   42488814 42068768 41698736 41748646 41338603 
            40768634 40738638 40658664 40658746 40638748 
            40608773 40668871 40658922 40828987 41179021 
            41778981 42018930 42168905 42428853