MESOSCALE PRECIPITATION DISCUSSION 0275
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1115 AM EDT SAT JUN 09 2018

AREAS AFFECTED...SOUTHERN MN

CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY

VALID 091515Z - 092030Z

SUMMARY...SLOW-MOVING BANDS OF HEAVY SHOWERS AND THUNDERSTORMS MAY
BECOME A BIT MORE CONCENTRATED OVER THE NEXT FEW HOURS AND WILL
PROMOTE FLASH FLOODING CONCERNS AS HEAVY RAIN FALLS OVER
RELATIVELY WET SOIL CONDITIONS.

DISCUSSION...THE LATEST GOES-16 IR/WV IMAGERY SHOWS A VERY COMPACT
VORT CENTER OVER FAR SOUTHWEST MN THAT IS FOSTERING MULTIPLE
SLOW-MOVING BANDS OF HEAVY SHOWERS AND THUNDERSTORMS. THE
CONVECTION IS ELEVATED IN NATURE TO THE NORTHEAST OF A WAVY AND
QUASI-STATIONARY FRONT...HOWEVER THERE IS THE NOSE OF A 30 TO 40
KT SOUTHWEST LOW LEVEL JET ADVANCING UP AROUND THE EASTERN FLANK
OF THE MID LEVEL VORT CENTER AND OVER THIS SURFACE BOUNDARY.

A COMBINATION OF 850 MB SPEED CONVERGENCE ALONG WITH THE POOLING
OF 1000 TO 2000 J/KG OF MUCAPE UP ACROSS SOUTH-CENTRAL MN IS
STRONGLY SUPPORTING THE CONVECTIVE ORGANIZATION SEEN AT THIS TIME
AND ACTUALLY THERE HAS BEEN A SUBSTANTIAL COOLING OF CONVECTIVE
CLOUD TOPS OVER SOUTHERN MN OVER THE LAST HOUR WHICH IS INDICATIVE
OF THE FAVORABLE JUXTAPOSITION OF STRONGER MID LEVEL FORCING AND
INSTABILITY.

OVER THE NEXT SEVERAL HOURS...HEAVY RAINFALL WILL CONTINUE ACROSS
ESPECIALLY SOUTH-CENTRAL MN AND GRADUALLY IMPACTING SOUTHEAST MN
THIS AFTERNOON AS THE VORT CENTER MOVES EAST AND INTERACTS WITH
THE SOUTHWEST LOW LEVEL JET AND TRANSPORT OF FAVORABLE MOISTURE
AND DIURNALLY AIDED INSTABILITY. THE HRRR GUIDANCE IS LIKELY TOO
SLOW WITH ITS OVERALL CONVECTION EVOLUTION ACROSS ALL OF CENTRAL
AND SOUTHERN MN...BUT ITS FORECAST AMOUNTS OF 2 TO 4 INCHES...WITH
LOCALIZED AMOUNTS NEAR 5 INCHES SEEMS REASONABLE GOING THROUGH
MID-AFTERNOON. THIS WILL BE AIDED BY HOURLY RAINFALL RATES OF 1.5
TO 2 INCHES/HR WHICH ACTUALLY WILL EXCEED FFG VALUES.

GIVEN THE WET ANTECEDENT CONDITIONS IN MANY AREAS...THESE RAINFALL
RATES/TOTALS WILL LIKELY CAUSE FLASH FLOODING...AND ESPECIALLY
OVER THE MORE URBANIZED AREAS. WILL CONTINUE TO MONITOR.

ORRISON

ATTN...WFO...ARX...DMX...FSD...MPX...

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

LAT...LON   45239448 45119340 44879270 44429190 43869147
            43529193 43499319 43649424 43989505 44429576
            44699596 45059554