MESOSCALE PRECIPITATION DISCUSSION 0423
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1134 PM EDT SUN JUL 08 2018

AREAS AFFECTED... NERN SD INTO WRN MN

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 090333Z - 090830Z

SUMMARY...A FLASH FLOOD THREAT WILL LINGER OVER NORTHEASTERN SOUTH
DAKOTA INTO CENTRAL MINNESOTA THROUGH ABOUT 08Z. RAINFALL RATES OF
1-2 IN/HR AND LOCALIZED TOTALS NEAR 3 INCHES CAN BE EXPECTED
BEFORE A FORECAST WEAKENING OF AN ONGOING CONVECTIVE COMPLEX.

DISCUSSION...GOES 16 10.3 MICRON IMAGERY OVERLAID WITH LIGHTNING
PLOTS SHOWED A HEALTHY CONVECTIVE COMPLEX OVER THE NORTH-CENTRAL
U.S. WITH TWO MAIN POINTS OF REGENERATION...ONE OVER NORTHEASTERN
SOUTH DAKOTA AND THE OTHER OVER WEST-CENTRAL MINNESOTA. MOSTLY
ELEVATED CONVECTION WAS OCCURRING JUST AHEAD OF A 700 MB TROUGH
AXIS ORIENTED FROM NORTHEASTERN MINNESOTA INTO EASTERN SOUTH
DAKOTA...WITH THE KABR 700 MB VAD WIND PLOT SHOWING VEERING OVER
THE PAST HOUR INDICATING THE TROUGH AXIS HAS JUST PASSED. THE
STORMS WERE BEING FED VIA A SOUTH-SOUTHWESTERLY 30-40 KT 850 MB
JET AXIS OVER EASTERN SOUTH DAKOTA AND MUCAPE OF 1000-2000 J/KG
VIA THE LATEST SPC MESOANALYSIS...AMID A STRONGLY DIFFLUENT FLOW
PATTERN ALOFT.

ALIGNMENT OF THE WESTERLY CLOUD-BEARING LAYER MEAN WIND OF 30-40
KT AND 850-700 MB MEAN WIND OF 30 KT FROM THE WEST HAS ALLOWED FOR
REPEATING/TRAINING OF HEAVY RAIN ECHOES WITH A RECENT REPORT OF
1.36 INCHES IN 20 MINUTES OUT OF DAY COUNTY IN NORTHEASTERN SOUTH
DAKOTA. A GRADUAL WEAKENING OF THE COMPLEX IS EXPECTED OVER THE
NEXT 3-5 HOURS AS INSTABILITY WANES BUT NOT BEFORE CONTINUED
POCKETS OF HEAVY RAIN ACROSS PORTIONS OF EASTERN SOUTH DAKOTA INTO
MINNESOTA...WITH A CONTINUED SOUTHWARD PUSH OVERALL AHEAD OF THE
700 MB TROUGH AXIS.

OTTO

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

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

LAT...LON   46709487 46439347 45929331 45349357 44809437
            44499571 44699701 45199782 45459792 45849774
            46089680 46469608