MESOSCALE PRECIPITATION DISCUSSION 0280
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
349 PM EDT SAT AUG 16 2014
 
AREAS AFFECTED...CENTRAL/EASTERN ND...FAR NORTHEAST SD...FAR
WEST-CENTRAL MN 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 161940Z - 170000Z
 
SUMMARY...VERY SLOW-MOVING SHOWERS AND THUNDERSTORMS TO PERSIST
THROUGH THE AFTERNOON. NEW DEVELOPMENT OF HEAVY RAINS ARE
EXPECTED. FLASH FLOODING IS LIKELY.

DISCUSSION...A WELL-DEFINED SURFACE LOW CENTER AND ACCOMPANYING
MID LVL VORT CENTER OVER S CNTRL ND IS EXPECTED TO MOVE VERY
SLOWLY EASTWARD THIS AFTERNOON AND EVENING WHILE INTERACTING WITH
A FRONTAL ZONE THAT HAS PUSHED SWWD INTO THE UPR MS VLY AND IS
DRAPED OVER TOP OF THE SFC WAVE. MEANWHILE...THE LATEST RAP
ANALYSIS SHOWS A POOL OF SBCAPE VALUES EXCEEDING 2000 TO 3000 J/KG
OVER MUCH OF SERN ND...NERN SD...AND CNTRL MN WHICH IS TO THE EAST
OF THE SFC LOW AND AN ATTENDANT SFC TROF...AND SOUTH OF THE
FRONTAL ZONE.

THE LATEST VIS IMAGERY SHOWS AN INCREASINGLY AGITATED CU/TCU FIELD
OVER THESE AREAS AS DIURNAL HEATING CONTINUES AND CAPE VALUES
INCREASE. AIDING THE UNSTABLE SFC AIRMASS IS A POOL OF DEEPER
MOISTURE WITH SFC DEWPOINTS AROUND 70F. COLUMN PWATS ARE NOTED TO
BE AOA 1.5 INCHES...AND ALREADY ONGOING PERSISTENT COLD-TOPPED
CONVECTION OVER S CNTRL ND HAVE BEEN PRODUCING RAINFALL RATES NEAR
2 INCHES/HR.

OVER THE NEXT FEW HOURS...CONVECTION WILL PERSIST OVER S CNTRL ND
AND WILL LIKELY DEVELOP IN A BKN FASHION OFF TO THE EAST ALONG AND
ADJACENT THE WELL-DEFINED FRONTAL ZONE...EXTENDING AS FAR EAST AS
W CNTRL MN. THERE MAY WELL BE SOME CONVECTION DEVELOPING FARTHER
SOUTH ALONG AND AHEAD OF THE SFC TROF INVOLVING NERN SD AS
WELL...BUT THE MOST CONCENTRATED THREAT OF ORGANIZED AND REPEATING
CONVECTION...INCLUDING SOME CELL MERGERS WILL BE OVER CNTRL AND
SOUTHEAST ND THROUGH THE AFTERNOON.

GIVEN INTENSE RAINFALL RATES UP TO 2 INCHES/HR AND THE
SLOW-MOVEMENT...ADDITIONAL FLASH FLOODING IS EXPECTED WITH THE
THREAT GRADUALLY SHIFTING EAST THIS AFTERNOON.

ORRISON

ATTN...WFO...FGF...ABR...BIS...

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

LAT...LON   45599907 46209958 46670010 46910055 47330068 47700015
            47759925 47579818 47329685 47019563 46429563 46089694
            45549785 45599907