MESOSCALE PRECIPITATION DISCUSSION 0345
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
702 AM EDT THU SEP 04 2014
 
AREAS AFFECTED...CENTRAL MN & NORTHERN WI 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 041101Z - 041531Z
 
SUMMARY...A TRAINING BAND OF HEAVY RAINFALL HAS BEEN MOVING
THROUGH EASTERN ND AND CENTRAL MN.  AS IT IS ABOUT TO MOVE INTO A
SATURATED AREA FROM YESTERDAY'S RAINFALL ACTIVITY WITH HOURLY RAIN
RATES OF CLOSE TO 2.5", FLASH FLOODING IS POSSIBLE IN THIS REGION
OVER THE NEXT SEVERAL HOURS.

DISCUSSION...A PAIR OF MESOCYCLONES ARE TRAVELING ALONG THE SAME
PATH INTO CENTRAL MN, WITH THE LEADING EDGE OF THE THUNDERSTORM
AREA MOVING SOUTH OF DUE EAST AT ~45 KTS AT THE LEADING EDGE OF A
LOW- TO MID-LEVEL CAP, ELEVATED OVER A STATIONARY FRONT.  HOURLY
RAIN RATES OF 3-4" HAVE BEEN INDICATED BY RADAR WITHIN THIS
TRAINING SCENARIO.  SINCE THERE HAVE BEEN HAIL REPORTS WITHIN THE
BAND, 2-3" HOURLY RATES HAVE LIKELY BEEN REALIZED.  MODERATELY
BROAD INFLOW AT 850 HPA IS 30-40 KTS PER RECENT VAD WIND PROFILES
-- SIMILAR TO THE MEAN 850-400 HPA WIND -- AND CAPE VALUES
UPSTREAM (TO THE SOUTHWEST) REMAIN 1000-2000 J/KG.  PRECIPITABLE
WATER VALUES ARE IN THE 1.50-1.75" RANGE PER RECENT RAP RUNS AND
GPS PW VALUES.  THE CURRENT ACTIVITY IS LIKELY TO CONTINUE INTO
THE SHORT TERM.

THE MESOSCALE GUIDANCE HAS BEEN UNDERFORECASTING RAINFALL AMOUNTS
WITH THIS BAND, WHICH HAS MADE INTERPRETING THEIR QPF OUTPUT
DIFFICULT.  THE BEST SIGNAL FOR HEAVY RAINFALL IN THIS REGION
FADES IN THE 15-16Z TIME FRAME DUE TO SLOWLY FADING 850 HPA
INFLOW, SO USED THAT AS A HORIZON FOR THE MPD.  THE PRESENCE OF
MESOCYCLONES WITHIN THIS BAND COULD LEAD TO GREATER PERSISTENCE TO
THE HEAVY RAINFALL, SO WILL CONTINUE TO MONITOR THE SITUATION. 
HOURLY RAIN RATES UP TO 2.5", WITH LOCAL TOTALS OF 3-5", REMAIN
POSSIBLE.  DUE TO THE SATURATED CONDITIONS AHEAD OF THE BAND,
FLASH FLOODING IS CONSIDERED POSSIBLE UNTIL ~1530Z.

ROTH

ATTN...WFO...ARX...DLH...FGF...GRB...MPX...

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

LAT...LON   46939486 46709201 45828861 44838812 44388896 
            45019127 45849425 46269574 46699588