MESOSCALE PRECIPITATION DISCUSSION 0682
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
556 AM EDT WED SEP 21 2016
 
AREAS AFFECTED...FAR SERN MN INTO SWRN WI 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 210956Z - 211430Z
 
SUMMARY...A SMALL AREA OF FLASH FLOODING STILL APPEARS POSSIBLE
ACROSS THE SRN MN/WI BORDER EXTENDING SOUTH TO THE NRN IA BORDER
WITH WI. RAINFALL RATES OF 1-2 IN/HR WITH REPEATING CELL MOTIONS
SHOULD CAUSE FLASH FLOODING FOR LOCATIONS IN AND AROUND THE
MISSISSIPPI RIVER.

DISCUSSION...COLD POOL ESTABLISHMENT ALONG THE WRN EDGE OF A
FORWARD PROPAGATING MCS APPEARS TO HAVE ANCHORED BETWEEN AUM AND
TOB...EXTENDING SEWD INTO NERN IA AS OF 09Z. KARX RADAR IMAGERY
OVER THE PAST HOUR HAS SHOWN ATTEMPTS AT REPEATING CELL MOTIONS
EAST OF THIS BOUNDARY AS NOTED IN WINONA COUNTY WHERE DUAL POL
ESTIMATED RAINFALL RATES REACHED 2 IN/HR JUST PAST 09Z. 

SHORT TERM RAP FORECASTS SHOW A RELATIVELY NARROW CORRIDOR OF
STRONGER 850-700 MB FLOW OVERRUNNING THE QUASI-STATIONARY WRN EDGE
OF THE OUTFLOW BOUNDARY OVER THE NEXT FEW HOURS. THE MAGNITUDE OF
THIS FLOW IS CURRENTLY 35 KTS AS SEEN ON THE KARX VAD WIND
PROFILE...AND IS FORECAST TO WEAKEN TO ROUGHLY 25 KTS BY 13Z.
GIVEN INDIVIDUAL STORM MOTIONS CONTINUE TO AVERAGE NEAR 30 KTS
TOWARD THE EAST...CONTINUED TRAINING OF CONVECTION IS
EXPECTED...WITHIN A NARROW CORRIDOR NEAR THE MISSISSIPPI RIVER. BY
15Z...LOW TO MID LEVEL FLOW SHOULD BEGIN TO BACK IN ADVANCE OF AN
APPROACHING MID LEVEL SHORTWAVE CURRENTLY OVER THE CNTRL HIGH
PLAINS...WHICH SHOULD DISRUPT THIS REGION OF TRAINING. ADDITIONAL
RAINFALL TOTALS OF 2-3 INCHES WILL BE POSSIBLE THROUGH 15Z. GIVEN
A HISTORY OF OBSERVATIONS REPORTING 1+ INCHES IN 30 MINUTES...AND
THE RELATIVELY FLOW FLASH FLOOD GUIDANCE AREA WIDE...FLASH
FLOODING IS CONSIDERED POSSIBLE ON A LOCALIZED BASIS. 

OTTO

ATTN...WFO...ARX...MKX...MPX...

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

LAT...LON   44779231 44389056 43148957 42609052 42939162 
            44109303