MESOSCALE PRECIPITATION DISCUSSION 0381
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1133 PM EDT SAT JUN 30 2018

AREAS AFFECTED...SE NE...NRN KS...NW MO...IA...SE MN...WRN WI

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

VALID 010105Z - 010530Z

SUMMARY...CONVECTIVE CLUSTERS DEVELOPING ALONG A FRONTAL BOUNDARY
WILL TRAIN IN A HIGH MOISTURE ENVIRONMENT...RESULTING IN FLASH
FLOODING INTO THE LATE EVENING HOURS.

DISCUSSION...THE GOES-16 CLEAN IR LOOP SHOWED BURSTS OF COLDER
CLOUD TOPS AS CONECTIVE CLUSTERS CONTINUE TO FILL IN ALONG AND
AHEAD OF FRONTAL BOUNDARY EXTENDING FROM WESTERN WI TO NORTHERN
KS...WHERE MLCAPE VALUES RANGE BETWEEN 3000-4000 J/KG (WHICH IS
CONFIRMED BY 00Z SOUNDINGS). A 25 TO 35 KNOT LOW LEVEL
SOUTH-SOUTHWESTERLY FLOW (PER REGIONAL VWP FROM OK INTO IA/WI)
CONTINUES TO TRANSPORT 1.75/2.00 INCH PRECIPITABLE WATER AIR ALONG
THE FRONT.

KDMX RADAR INDICATED HOURLY RAINFALL RATES NEAR 2.00 INCHES OVER
PORTIONS OF CENTRAL IA...NEAR AND JUST SOUTHEAST OF THE FRONT. THE
00Z SOUNDINGS ACROSS THE REGION SHOWED WET BULB ZERO VALUES CLOSE
TO THE FREEZING LEVEL...INDICATING THE WARM RAIN PROCESSES ARE
COMING INTO PLACE. LOTS OF SMALLER RAIN DROPS IN THE COLUMN SHOULD
RESULT IN EFFICIENT RAINFALL PRODUCERS...AND RAINFALL RATES
BETWEEN 2.00 AND 3.00 INCHES ARE POSSIBLE ALONG THE FRONT FROM FAR
SOUTHEAST NEBRASKA ACROSS CENTRAL IOWA INTO WESTERN WISCONSIN (AS
INDICATED BY THE MOST RECENT HRRR/EXPERIMENTAL HRRR RUNS).

THE 250-MB FLOW BECOMES INCREASINGLY DIVERGENT IN THE ENTRANCE
REGION OF A 90 KT JET EXITING EASTERN NORTH DAKOTA FOR WESTERN
ONTARIO...PROVIDING SUFFICIENT SYNOPTIC SCALE LIFT TO ALLOW
CONVECTION TO INCREASE IN COVERAGE THROUGH AT LEAST 05Z. THE MOST
RECENT HRRR/EXPERIMENTAL HRRR EACH SHOWED LOCAL RAINFALL AMOUNTS
BETWEEN 3 AND 5 INCHES...WITH THE HIGHEST AMOUNTS OVER FAR
SOUTHEASTERN NEBRASKA AND FAR WESTERN WISCONSIN. BASED ON THE
DEPTH OF THE MOISTURE IN PLACE...THESE AMOUNTS SEEM PLAUSIBLE.

THIS MUCH RAINFALL...OVER AREAS THAT HAVE BEEN SATURATED BY HEAVY
RAINFALL OVER THE PAST WEEK OR SO...IS EXPECTED TO RESULT IN FLASH
FLOODING NEAR AND SOUTHEAST OF THE FRONTAL BOUNDARY. IF TRAINING
OR BACKBUILDING OCCURS NEAR SURFACE WAVES ALONG THE
FRONT...SIGNIFICANT FLASH FLOODING IS POSSIBLE IN THE
AFORE-MENTIONED AREAS. AS THE FRONT SAGS SLOWLY SOUTHEAST...THE
THREAT FOR FLASH FLOODING SHOULD FOLLOW SUIT. THE THREAT FOR FLASH
FLOODING IS EXPECTED TO CONTINUE AFTER 05Z.

HAYES

ATTN...WFO...ARX...DLH...DMX...DVN...EAX...FSD...GID...GRB...
MKX...MPX...OAX...TOP...

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

LAT...LON   45389015 44888935 43658898 42419047 40709375
            39809595 39929676 40199741 40749753 41269692
            43279388