MESOSCALE PRECIPITATION DISCUSSION 0121
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1155 PM EDT SAT JUN 22 2013
 
AREAS AFFECTED...FAR SOUTHEAST MN...NORTHEAST IA...SOUTHERN WI 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 230355Z - 230655Z
 
SUMMARY...CELL TRAINING ALONG AN ORGANIZED BAND OF THUNDERSTORMS
ACROSS SOUTHERN WI AND NORTHEAST IA WILL MAINTAIN THE LIKELIHOOD
OF FLASH FLOODING ACROSS THE REGION OVER THE NEXT FEW HOURS.

DISCUSSION...A BAND OF THUNDERSTORMS INITIATING ALONG/NEAR A
SURFACE FRONT ACROSS NORTHEAST IA AND MOVING DOWNSTREAM ACROSS
SOUTHERN WI ARE EXPECTED TO REMAIN QUASI-STATIONARY OVER THE NEXT
FEW HOURS.  DIVERGENCE ALOFT REMAINS ACROSS THE AREA TO THE EAST
OF AN UPPER LEVEL LOW MOVING ALONG THE WY/MT BORDER.  WHILE A
LOW-LEVEL COOL POOL HAS BEEN TRYING TO NUDGE THE ACTIVITY
SOUTHWARD, THE BEST 850 HPA INFLOW OF 35-40 KNOTS (WHICH COULD
SLIGHTLY INCREASE OVERNIGHT) IS EXPECTED TO NUDGE NORTHWARD, WHICH
LEADS TO THE EXPECTATION OF LITTLE MOVEMENT TO THIS LINE.  THE
STRENGTH OF THE LOW-LEVEL INFLOW, WHICH SHOULD SLIGHTLY INCREASE,
SEEMS TO GUARANTEE THIS SYSTEM'S CONTINUED ORGANIZATION.  THE MEAN
STEERING FLOW REMAINS PARALLEL TO THE 850 HPA INFLOW, WHICH SHOULD
KEEP CONVECTION WITHIN THE PLUME OF HIGHEST AVAILABLE MOISTURE.
INSTABILITY WITHIN THE WARM SECTOR REMAINS IMPRESSIVE, AS
SATELLITE-DERIVED ESTIMATES ARE 4000-6000 J/KG ACROSS EASTERN IA. 
PRECIPITABLE WATER VALUES ARE 1.75-2 INCHES, AROUND TWO STANDARD
DEVIATIONS ABOVE NORMAL AND WITHIN THE 90TH PERCENTILE FOR JUNE. 
LOCAL AMOUNTS OF 3-5 INCHES WITHIN THE NEXT FEW HOURS SHOULD
SIGNIFICANTLY EXCEED THE FLASH FLOOD GUIDANCE, WHICH IS CLOSE TO
1.5 INCHES IN THREE HOURS.  FLASH FLOODING CONTINUES TO BE LIKELY
IN THIS REGION.

ROTH

ATTN...WFO...GRB...MKX...ARX...

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

LAT...LON   43888756 43078721 42588760 42568934 42749088 43519215
            44159206 44599114 44458886 43888756