MESOSCALE PRECIPITATION DISCUSSION 0356
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1050 PM EDT SUN JUN 24 2018

AREAS AFFECTED...EASTERN NE...WESTERN IA...EXTREME SOUTHEAST
SD...SOUTHWEST MN

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

VALID 250250Z - 250730Z

SUMMARY...ADDITIONAL SLOW-MOVING SHOWERS AND THUNDERSTORMS WITH
HEAVY RAINFALL RATES WILL FOSTER MORE FLASH FLOODING CONCERNS OVER
THE NEXT FEW HOURS.

DISCUSSION...SOME ADDITIONAL CONVECTIVE CLOUD TOP COOLING IS SEEN
OVER THE TRI-STATE AREA OF NE/SD/IA AS A VERY SLOW-MOVING COLD
FRONT APPROACHES FROM THE WEST OUT AHEAD OF A SHORTWAVE TROUGH
EJECTING OUT ACROSS THE PLAINS. THE BOUNDARY LAYER AIRMASS AHEAD
OF THE FRONT REMAINS MODERATELY UNSTABLE WITH AS MUCH AS 1500 TO
2000 J/KG OF MLCAPE AND THIS HAS BEEN AIDING NEW DEVELOPMENT OVER
THE LAST COUPLE OF HOURS WITH SUPPORT ALSO OF A RATHER DIVERGENT
FLOW PATTERN ALOFT.

OVER THE NEXT FEW HOURS...THE RELATIVELY NARROW AXIS OF FAVORABLE
INSTABILITY SHOULD GRADUALLY BECOME EXHAUSTED WITH CONVECTIVE
OVERTURNING AND LOSS OF DAYTIME HEATING...BUT THE CONVECTION THAT
IS ONGOING WILL BE RATHER SLOW-MOVING AND THIS WILL STILL PROMOTE
HEAVY RAINFALL TOTALS.

THE PWATS ARE GENERALLY 1.5 TO 1.7 INCHES BASED ON THE LATEST
GPS-DERIVED DATA...AND THIS WILL FAVOR VERY HEAVY RAINFALL RATES
THAT COULD EXCEED 2 INCHES/HR WITHIN THE STRONGER CONVECTIVE
CORES/UPDRAFTS.

THE HRRR/HRRRX GUIDANCE FAVORS SOME ADDITIONAL TOTALS LOCALLY OF 3
TO 4 INCHES WITH ISOLATED HEAVIER AMOUNTS GOING THROUGH 06Z...AND
THIS WILL LIKELY CAUSE SOME ADDITIONAL FLASH FLOODING.

ORRISON

ATTN...WFO...DMX...FSD...GID...MPX...OAX...TOP...

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

LAT...LON   44119544 44009452 43309359 42309379 41209548
            40239671 39999755 40389832 41789743 42949706
            43719662