MESOSCALE PRECIPITATION DISCUSSION 0035
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1146 PM EDT WED APR 08 2015
 
AREAS AFFECTED...FAR EASTERN IL/IN... 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 090346Z - 090831Z
 
SUMMARY...AN UPSTREAM LINE OF SHOWERS AND THUNDERSTORMS HAVE BEEN
PRODUCING RADAR-ESTIMATED HOURLY RAIN RATES OF 1-1.25 INCHES/HOUR.
THERE IS REASONABLE CONFIDENCE THIS CONVECTION WILL REACH THE MPD
AREA BY ROUGHLY 06Z WHICH WILL ENHANCE THE RISK OF FLASH FLOODING
OVERNIGHT.

DISCUSSION...THE 03Z SURFACE ANALYSIS SHOWED A WAVY FRONTAL ZONE
EXTENDING FROM NORTHERN MO EASTWARD THROUGH CENTRAL IL/IN/OH.
SUFFICIENT LOW-LEVEL MOISTURE HAS CONTINUED TO WORK ITS WAY
NORTHWARD VIA THE PERSISTENT SOUTH-SOUTHWESTERLY FLOW. CURRENT
PWATS RANGE FROM 1 TO 1.25 INCHES ACROSS THE MPD AREA. THE BIGGEST
QUESTION MARK IS REGARDING THE AMOUNT OF ELEVATED INSTABILITY
EXPECTED TO LINGER INTO THE OVERNIGHT HORUS. THE 00Z ILX SOUNDING
SUGGESTS THERE IS STILL PLENTY OF CAPE IN THE ATMOSPHERE WITH 2177
J/KG NOTED...MOSTLY IN THE FORM OF ELEVATED INSTABILITY. WHILE THE
AIR MASS DOWNSTREAM WAS CONVECTIVELY OVERTURNED EARLIER IN THE
EVENING...IT APPEARS THE ATMOSPHERE HAS RECOVERED  SUFFICIENTLY TO
SUPPORT ADDITIONAL CONVECTION ACROSS IN.

UNFORTUNATELY THE CONVECTION-ALLOWING MODELS HAVE STRUGGLED
MIGHTILY WITH THE EVOLUTION OF THIS THUNDERSTORM COMPLEX. GIVEN
THE HRRR UPDATES HOURLY...THE 02Z HRRR AT LEAST OFFERED SOME
SHORT-TERM USE. THIS WAS USED IN CONJUNCTION WITH SURFACE
OBSERVATIONS AND SATELLITE TRENDS. OVERALL...THE AFFECTED REGION
MAY SEE A POSSIBILITY OF FLASH FLOODING GIVEN THE FACT FFG VALUES
HAVE DIMINISHED SIGNIFICANTLY IN THE PAST SEVERAL HOURS. WILL
CONTINUE TO MONITOR THE AREA OVERNIGHT.


RUBIN-OSTER

ATTN...WFO...ILN...ILX...IND...IWX...LMK...PAH...

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

LAT...LON   40838562 40758506 40348477 39388482 38828527 
            38528567 38288654 38378736 38878784 39998774 
            40558618