MESOSCALE PRECIPITATION DISCUSSION 0261
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
726 PM EDT MON JUN 22 2015
 
AREAS AFFECTED...SOUTHEAST IA...NORTHERN IL...EXTREME NORTHERN MO 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 222325Z - 230230Z
 
SUMMARY...THERE WILL BE INCREASING RISK OF FLASH FLOODING OVER
PARTS OF SOUTHEAST IA...NORTHERN IL AND EXTREME NORTHERN MO THIS
EVENING.  

DISCUSSION...PORTIONS OF SOUTHEAST IA AND NORTHERN IL WILL BE IN A
POSITION FOR HEAVY RAINFALL FROM STORMS MOVING GENERALLY WEST TO
EAST ACROSS THE AREA THIS EVENING.

STORMS WERE BECOMING MORE NUMEROUS OVER SOUTHEAST IA EARLY THIS
EVENING AHEAD OF AN APPROACHING SFC COLD FRONT AND ALONG THE
INTERFACE BETWEEN AN AIRMASS WORKED OVER BY LAST NIGHTS MCS AND AN
UNMODIFIED AIRMASS TO THE SOUTH.  IN ADDITION...A MID LEVEL VORT
ELONGATED ALONG THE BORDER OF SOUTHEAST SD AND NORTHEAST NE SHOULD
AID AND FOCUS CONVECTIVE DEVELOPMENT.

THE AIRMASS AHEAD OF THE FRONT WAS UNSTABLE WITH SURFACE BASED
CAPES BETWEEN 4000 J/KG AND 5000 J/KG.  WHILE SOME DROP OFF IN THE
CAPE IS EXPECTED FOLLOWING SUNSET...PRECIPITABLE WATER VALUES IN
EXCESS OF 1.50 INCHES SHOULD CONTINUED TO BE DRAWN INTO THE AREA
WHICH WILL HELP STORMS CONTINUE TO BE EFFICIENT RAINFALL
PRODUCERS.  

THE NAM CONEST SEEMED TO HAVE THE BEST HANDLE ON THE EVOLUTION OF
THE STORMS IN THE SHORT TERM.  RUNS OF THE WRF/ARW...WRF/NMMB AND
ARW SEEMED TO BE SLOW TO INITIATE CONVECTION AND TO TRANSLATE
CONVECTION EASTWARD.  WHEN THOSE MODELS DID DEVELOP STORMS...IT
SEEMED THAT THOSE MODELS WOULD END UP BEING A BIT TOO FAR NORTH
WITH THE TRACK.  

RAINFALL RATES OF 1 TO 2 INCHES PER HOUR ARE EXPECTED...WITH
LOCALLY MORE INTENSE RATES POSSIBLE.  FLASH FLOOD GUIDANCE NUMBERS
WERE CLOSE TO 2 INCHES PER 3 HOURS...HENCE THE POSSIBILITY OF
FLASH FLOODING.  PROBLEMS DUE TO PONDING OF WATER AND RUNOFF MAY
OCCUR IN URBANIZED AREAS WHERE DRAINAGE IS POOR. 

BANN

ATTN...WFO...DMX...DVN...EAX...ILX...LOT...

ATTN...RFC...MBRFC...NCRFC...

LAT...LON   41918944 41798789 41278758 40768870 40578995 
            40469112 40459307 41049288 41849098