MESOSCALE PRECIPITATION DISCUSSION 0137
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
823 AM EDT WED JUN 26 2013
 
AREAS AFFECTED......SOUHERN WI...NORTHERN IL...NORTHERN IN 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 261223Z - 261623Z
 
SUMMARY...BANDS OF THUNDERSTORMS ARE EXPECTED TO PERSIST NEAR A
STATIONARY FRONT WITH AN ADDITIONAL 2-4 INCHES OF RAIN AND FLASH
FLOODING POSSIBLE

DISCUSSION...BANDS OF SHOWERS AND THUNDERSTORMS HAVE DEVELOPED IN
THE VICINITY OF A STATIONARY FRONT OVER SOUTHERN WI ACROSS
NORTHERN IL AND NORTHERN IN. 4.25 INCHES OF RAIN HAS BEEN OBSERVED
WITHIN THESE BANDS AT PALWAUKEE IL (JUST NORTH OF CHICAGO)FROM
09-12Z...WITH 5 INCHES IN THE COCORAHS OBSERVATIONS 2 MILES
NORTHEAST OF MCHENRY IL.
  
THE REGION IS WITHIN A BROAD 850-700 MB WARM/MOIST ADVECTION
REGION DOWNSTREAM FROM A MID-UPPER LEVEL TROUGH.  MID LEVEL
CYCLONIC VORTICITY ADVECTION IS OCCURRING WITH SPORADIC UPPER
DIVERGENCE MAXIMA SHOWN IN THE MODELS.

THE HEAVY RAIN SIGNAL WAS NOT AS EVIDENT IN THE ECMWF/GFS BUT
APPEARS IN THE NSSL WRF...NCEP WRF ARW AND WRF NMM.  THESE MODELS
SHOW POTENTIAL FOR A COUPLE OF INCHES OF RAIN OVER THE NEXT
SEVERAL HOURS.  THE GFS ESTIMATES ABOUT 1.75 INCHES OF
PRECIPITABLE WATER EXISTS AT 12Z WITH CONTINUED SIMILAR VALUES
PERSISTING THROUGH 18Z IN THE VICINITY OF THE STATIONARY FRONT.

MEAN LAYER WESTERLY FLOW EXISTS IN THE REGION WITH PROPAGATION TO
THE SOUTHEAST. THE 06Z GFS CORFIDI VECTORS SHOW THIS PERSISTING
THROUGH 18Z...SUPPORTING CONTINUED MOTION TO THE RIGHT OF THE MEAN
FLOW.

PETERSEN

ATTN...WFO...ILN...IWX...IND...LOT...MKX...DVN...

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

LAT...LON   42168701 41518573 40628445 40018477 40228553 41058732
            41888873 42788991 43518992 43318884 42678790 42168701