MESOSCALE PRECIPITATION DISCUSSION 0128
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
149 AM EDT TUE JUN 25 2013
 
AREAS AFFECTED...SOUTHEAST MN...EXTREME NORTHEAST IA...SOUTHERN
WI...NORTHERN IL...NORTHWEST IN...SOUTHWEST LOWER PENINSULA OF MI 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 250549Z - 250849Z
 
SUMMARY...A GROWING COMPLEX OF THUNDERSTORMS ACROSS THE UPPER
MIDWEST AND UPPER MISSISSIPPI VALLEY CONTINUES TO PRODUCE HEAVY
RAINFALL, WHICH IS NOW EXPANDING TOWARDS NORTHERN IL.  FLASH
FLOODING IS LIKELY IN THIS REGION.

DISCUSSION...A BURGEONING BAND OF THUNDERSTORMS CONTINUES TO
ORGANIZE ACROSS SOUTHEAST MN, EXTREME NORTHEAST IA, AND SOUTHERN
WI, WITH CONTINUED EVIDENCE OF BACKBUILDING ON RADAR IMAGERY --
ADVERTISED BY GFS-BASED CORFIDI VECTORS -- LEADING TO AN EAST-WEST
EXPANSION OF THE CONVECTION.  THIS CONVECTIVE AREA CONTINUES TO BE
ELEVATED NORTH OF A FRONTAL BOUNDARY DOWN ACROSS SOUTHEAST NE AND
NORTHERN MO AND NEAR AN AREA OF 750-650 HPA FRONTOGENESIS.  THE
AREA REMAINS DIVERGENT ALOFT SOUTH OF AN UPPER LEVEL LOW IN
ONTARIO AND TO THE EAST OF A NORTH-SOUTH ORIENTED UPPER-LEVEL
SHEAR LINE IN THE CENTRAL PLAINS.  

THE SOUTHERN PORTION OF THIS ACTIVITY IS EXPANDING SOUTHEAST AT A
FASTER RATE THAN THE 00Z HRRR, LIKELY DUE TO AN INCREASINGLY
WEST-EAST ALIGNMENT OF THE STRONGER LOW-LEVEL INFLOW TOWARDS
NORTHERN IL, WHICH HAS INCREASED TOWARDS 45 KNOTS AT 850 HPA. 
PRECIPITABLE WATER VALUES OF 1.75 EXIST ACROSS THE AREA, AND
SATELLITE-DERIVED CAPES REMAIN IN THE 2500-4000 J/KG RANGE
INDICATING SIGNIFICANT INSTABILITY CONTINUES ACROSS SOUTHERN WI
AND IA.  WITH THE EARLIER BAND OF THUNDERSTORMS IN EASTERN KS ON
THE DOWNTURN, THERE SEEMS TO BE LITTLE HINDRANCE TO THE CONTINUED
ORGANIZATION OF THIS CONVECTIVE CLUSTER CONSIDERING THE DEGREE OF
LOW-LEVEL INFLOW AVAILABLE.  HOWEVER, THE SOUTHEAST PORTION COULD
ORGANIZE ENOUGH TO BOW OUT AS A SQUALL LINE AND MOVE TO THE EAST
AND SOUTHEAST ACROSS NORTHERN IL INTO NORTHERN IN/SOUTHERN MI BY
09Z, WHICH WILL NEED TO BE WATCHED.  

RAINFALL RATES HAVE BEEN IMPRESSIVE WITH THE THUNDERSTORMS ACROSS
NORTHEAST IA AND SOUTHWEST WI, WITH 1.27" REPORTED IN 25 MINUTES
AROUND 0444Z, WHICH LED TO A BRIDGE WASHOUT IN IA.  AS FLASH FLOOD
GUIDANCE VALUES REMAIN AROUND 1.5 INCHES IN THREE HOURS, AND LOCAL
RAINFALL AMOUNTS OF 2-4 INCHES ARE EXPECTED, FLASH FLOODING IS
LIKELY IN THIS REGION.

ROTH

ATTN...WFO...IWX...GRR...GRB...LOT...MKX...DVN...ARX...MPX...
DMX...

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

LAT...LON   44709164 44438983 43588724 42488581 41128618 40648760
            41518987 43039236 43679316 44329294 44709164