MESOSCALE PRECIPITATION DISCUSSION 0115
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
400 AM EDT FRI JUN 21 2013
 
AREAS AFFECTED...SOUTH-CENTRAL MN...CENTRAL WI 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 210800Z - 211200Z
 
SUMMARY...A MESOSCALE CONVECTIVE COMPLEX -- MCC -- IS EXPECTED TO
CONTINUE MOVING EASTWARD, LEADING TO POSSIBLE FLASH FLOODING
ACROSS THE REGION.

DISCUSSION...AN MCC MOVING ACROSS MN IS EXPECTED TO MAINTAIN ITS
INTEGRITY AS IT MOVES INTO WISCONSIN EARLY THIS MORNING.  THE
SYSTEM IS BEING FED BY A FEW INFLOW BANDS MOVING INTO THE REGION
FROM EASTERN SD, SOUTHERN MN, AND WESTERN WI, WITH THE BULK OF THE
SYSTEM NEAR AND NORTH OF A FRONTAL ZONE.  FLASH GUIDANCE REMAINS
NEAR 2.5 INCH WITHIN THREE HOURS, WHICH HAS BEEN EXCEEDED
OVERNIGHT REGIONALLY.  HOWEVER, THE SYSTEM IS MOVING QUICKER AND
HAS A SOMEWHAT SMALLER RAINFALL FOOTPRINT ALONG A WEST-EAST AXIS
THAN SEEN EARLIER OVERNIGHT, WHICH LEADS TO A SMALLER RISK OF
FLASH FLOODING ON A REGIONAL BASIS.  DIVERGENCE ALOFT REMAINS
SIGNIFICANT TO THE EAST OF AN UPPER LEVEL LOW.  LOW-LEVEL INFLOW
NEAR AND BELOW THE 850 HPA LEVEL IS CLOSE TO 50 KNOTS, WHICH IS
FEEDING UNSTABLE AIR INTO THE SYSTEM WITH SATELLITE-DERIVED CAPE
VALUES OF 5000-6000 J/KG.  CONVERGENCE ALONG THE FRONTAL ZONE HAS
LED TO PRECIPITABLE WATER VALUES OF 1.75-2 INCHES, WHICH IS OVER
TWO STANDARD DEVIATIONS ABOVE NORMAL FOR THE REGION FOR JUNE. THIS
SYSTEM IS EXPECTED TO PERSIST WELL INTO THE MORNING HOURS PER THE
LAST SEVERAL RUNS OF THE HRRR.  CONSIDERING THE ABOVE, USED
POSSIBLE WORDING.  LOCAL AMOUNTS OF 3-5 INCHES WITHIN A FEW HOURS
CANNOT BE RULED OUT, WHICH WOULD EXCEED FLASH FLOOD GUIDANCE.

ROTH

ATTN...WFO...GRB...MKX...DLH...ARX...MPX...FSD...ABR...

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

LAT...LON   44529651 45709486 46089165 45178919 43288869 43429022
            44019254 44529651