MESOSCALE PRECIPITATION DISCUSSION 0479
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1259 AM EDT SUN SEP 06 2015
 
AREAS AFFECTED...NORTHERN MN & VICINITY 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 060458Z - 061058Z
 
SUMMARY...NEW THUNDERSTORMS ARE CONGEALING ACROSS NORTHWEST MN,
THREATENING AREAS WHICH RECEIVED HEAVY RAINFALL OVER THE PAST 29
HOURS.  FLASH FLOODING IS POSSIBLE.

DISCUSSION...A STATIONARY FRONT ACROSS CENTRAL MN IS ACTING AS THE
FOCUS FOR NEW CONVECTION ACROSS NORTHWEST MN.  INFLOW AT 850 HPA
OF 35-45 KTS (ABOVE THE MAGNITUDE OF THE MEAN 850-400 HPA WIND) IS
IMPORTING MUCAPES OF 2000 J/KG OVER THE BOUNDARY.  PRECIPITABLE
WATER VALUES ARE NEAR 2", WHICH IS NEAR RECORD TERRITORY FOR EARLY
SEPTEMBER IN THIS REGION, SUPPORTING HOURLY RAIN RATES UP TO 2.5".

THE BREADTH/STRENGTH OF THE INFLOW IS EXPECTED TO CONTINUE OVER
THE NEXT SEVERAL HOURS WHILE THE LOW-LEVEL INFLOW SLOWLY VEERS,
IMPLYING FORWARD PROPAGATION WITH TIME.  THIS DEGREE OF
INSTABILITY IS EXPECTED TO REMAIN UNDISTURBED BY CONVECTION,
IMPLYING IT COULD AID ORGANIZED ACTIVITY FOR SEVERAL MORE HOURS. 
FLASH FLOOD GUIDANCE VALUES DECREASED DUE TO FRIDAY NIGHT'S RAIN
NEAR BIG FORK MN, AND AREAS FARTHER SOUTH RECEIVED HEAVY RAINFALL
THIS PAST EVENING OVER PORTIONS OF CROW WING COUNTY.  THE 00Z CAM
GUIDANCE BROUGHT AMOUNTS UP IN THIS REGION, WITH LOCAL AMOUNTS OF
3-5" INDICATED, THOUGH LIKELY PLACED TOO FAR TO THE NORTH.  A
COMBINATION OF FORWARD PROPAGATING CONVECTIVE VECTORS AND THE
1000-500 HPA THICKNESS PATTERN IMPLIES AN EAST TO EAST-NORTHEAST
MOTION OF 30 KTS TO ORGANIZED CONVECTION.  CELL TRAINING/MERGERS
ARE THE MAIN THREAT.  THE FLASH FLOOD GUIDANCE IS QUITE VARIED
ACROSS THIS REGION DUE TO FORESTS, LAKES, AND MARSHLAND.  USED THE
POSSIBLE CATEGORY DUE TO THIS CONSIDERATION.

ROTH

ATTN...WFO...ABR...DLH...FGF...MPX...

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

LAT...LON   48649303 48379244 47179158 46039184 46009441 
            45949663 47089652 47839556 48399455 48619390 
            48629366