MESOSCALE PRECIPITATION DISCUSSION 0120...CORRECTED
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1113 PM EDT SAT JUN 22 2013
 
AREAS AFFECTED...NORTHERN NE...EASTERN SD...SOUTHERN MN 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 230254Z - 230654Z
 
SUMMARY...AN ELEVATED WARM FRONT IS ACTING AS THE FOCUS FOR NEW
CONVECTION FROM NORTHERNMOST NE ACROSS EASTERN SD INTO SOUTHERN
MN.  FLASH FLOODING IN LIKELY IN THIS AREA.

DISCUSSION...A RETURNING WARM FRONT -- MOST OBVIOUS WHERE IT
BISECTED THE 850 HPA PRESSURE SURFACE -- IS FIRING A NEW ROUND OF
CONVECTION FROM NORTHERN NE ACROSS SOUTHEAST SD INTO SOUTHERN MN,
WHICH IS BEING DRIVEN BY BROAD AND CONFLUENT 40-50 KNOTS INFLOW
AROUND THE 850 HPA LEVEL.  LOW-LEVEL INFLOW THIS STRONG SHOULD
ALLOW THE CONVECTION TO DEVELOP INTO A MESOSCALE CONVECTIVE SYSTEM
BY 05Z.  A SIGNIFICANT AMOUNT OF CIN ACROSS EASTERN NE AND WESTERN
IA APPEARS TO BE CURRENTLY PREVENTING THE SURFACE FRONT ITSELF
FROM INITIATING CONVECTION -- PER THE 12Z ARW GUIDANCE -- THOUGH
WEAKENING CIN ACROSS NE THIS PERIOD COULD ALLOW THE SURFACE
BOUNDARY, WHICH SHOULD BE RETURNING AS A SURFACE WARM FRONT
SHORTLY, TO BECOME MORE OF A FACTOR FOR THUNDERSTORM INITIATION IN
THE NEXT FEW HOURS.  SATELLITE-DERIVED CAPE VALUES IN THE VICINITY
OF THE ELEVATED WARM FRONT ARE IN THE NEIGHBORHOOD OF 3500 J/KG. 
PRECIPITABLE WATER VALUES NEAR THIS BOUNDARY ARE AROUND 1.75
INCHES, A BIT ABOVE NORMAL FOR JUNE.  CORFIDI VECTORS ARE WEAK,
AND DIRECTED TOWARDS THE EAST-NORTHEAST IN THIS REGION.  THESE ARE
LIKELY BEING DRIVEN BY THE MEAN STEERING FLOW IN THIS REGION,
WHICH IS PARALLEL TO THE 850 HPA WIND PATTERN.  BY 05Z, EXPECT
THIS AREA TO JOIN WITH THE ACTIVE CONVECTIVE AREA ACROSS
WISCONSIN, WHICH IS HINTED AT IN 21Z HRRR RUN, AS THE INFLOW INTO
THIS BOUNDARY IS ACROSS A BROAD REGION.  UPSTREAM NEAR THE MT/ND
BORDER, MORE MOBILE THUNDERSTORMS DROPPED AROUND 5 INCHES OF RAIN.
 FLASH FLOOD GUIDANCE VALUES IN THIS AREA ARE NEAR OR BELOW 2
INCHES PER 3 HOUR PERIOD.  CONSIDERING THAT THIS CONVECTIVE AREA
WILL BE SLOWER MOVING THAN THE MT/ND BORDER ACTIVITY, BELIEVE THAT
A CONSERVATIVE ESTIMATE OF LOCAL RAINFALL AMOUNTS LIES IN THE
RANGE OF 3-6 INCHES, WHICH WILL CAUSE FLASH FLOODING.

ROTH

ATTN...WFO...ARX...MPX...DMX...FGF...FSD...OAX...ABR...LBF...
UNR...

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

LAT...LON   42679725 42539928 42790015 43700042 44919974 45609774
            45879520 45479285 44289173 43349319 42679725