MESOSCALE PRECIPITATION DISCUSSION 0372
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
900 PM EDT THU JUN 22 2017

AREAS AFFECTED...SOUTHEAST WI...NORTHEAST IL...CENTRAL MI...

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

VALID 230100Z - 230630Z

SUMMARY...SLOW MOVING/TRAINING CONVECTION PRIOR TO SEWARD PUSH OF
COLD FRONT LEADS TO MULTIPLE BOUTS OF HEAVY RAINFALL CAPABLE OF
FLASH FLOODING.  MORE CONFLUENT/TRAINING ACROSS LOWER FFG IN
CENTRAL MI MAY ALSO POSE FF RISK THERE AS WELL.

DISCUSSION...GOES-E AND RADAR MOSAIC DENOTES WARM SECTOR
CONVECTION BEGINNING TO BLOSSOM ACROSS SE WI WITH A SECOND CLUSTER
OF NUMEROUS OVERSHOOTING TOP IS CENTRAL MI. BOTH AREAS WERE ABLE
TO RECEIVE MODEST SOLAR INSOLATION LEADING TO TIGHT INSTABILITY
GRADIENT WITH MLCAPES TO 2000 J/KG IN WI AND 1250-1500 IN MI.  THE
LARGER WEAKENING CAP AND MODEST LARGE SCALE ASCENT FROM SOME
MODEST SPEED DIVERGENCE ALOFT ON THE SOUTHERN GRADIENT OF THE JET
ALONG WITH STRENGTHENING SSWLY LLJ WAS SUFFICIENT FOR THE AMOUNT
OF OVERTURNING.  THIS IS ALSO COINCIDENT WITH FAIRLY DEEP MOISTURE
TO SUPPORT TPWS OF 1.8 TO 1.9" THROUGHOUT THE REGION TO ALLOW FOR
CELLS TO BE FAIRLY EFFICIENT WITH RAIN RATES EXPECTED TO BE AT OR
ABOUT 2"/HR.  GIVEN UNIDIRECTIONAL CLOUD BEARING PROFILE CELLS
HAVE THE POTENTIAL TO TRACK JUST A FEW DEGREES OF DUE EAST...AND
GIVEN ORIENTATION OF THE DEVELOPMENT (PARTICULARY ALONG I-94 IN
WI) TRAINING/REPEAT IS EXPECTED ALLOWING FOR INCREASED TOTALS
LIKELY TO EXCEED THE MODEST FFG VALUES IN THE VICINITY ESPECIALLY
IN SE WI WHERE EVEN 3HR FFGS ARE 1.5-2".  ACROSS IN MI VALUES ARE
A BIT HIGHER BUT CELLS ARE LIKELY TO MOVE THOUGH THE LOCALIZED
MINIMUM IN THE FFG WITH VALUES OF 1.5"/3HR NORTH OF THE INITIAL
CLUSTER.

STILL A SECONDARY BOUT OF CONVECTION IS LIKELY TO SWEEP THROUGH IN
THE NEXT FEW HOURS AS THE COLD FRONT ADVANCES SOUTHEAST WITH
TIME...CURRENTLY LOWER INSTABILITY DUE TO PERSISTENT CLOUD COVER
HAS REDUCED VERTICAL DEPTH OF SHOWERS/STORMS ALONG THE FRONT...BUT
WILL INCREASE WITH STRENGTHENING LOW LEVEL JET AND DRIFT INTO ANY
REMAINING INSTABILITY WELLS NOT USED BY INITIAL ROUND.  THIS
ONE/TWO PUNCH INCREASES CONFIDENCE IN COVERAGE OF 2-3" TOTALS
CAPABLE OF FLASH FLOODING AS WELL.  AS THE FRONT DROPS SOUTH
TOWARD 05-06Z SHOWERS HAVE INCLUDED URBAN AREAS OF NE IL AS WELL
PRONE TO THESE HIGH INTENSITY RATES.

GALLINA

ATTN...WFO...APX...ARX...DTX...DVN...GRB...GRR...LOT...MKX...

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

LAT...LON   44228650 44078502 44168322 43908273 43368302
            42988477 42598613 41858754 41868777 41928841
            42188930 42439006 42979036 43479013 43828897
            43998799 44068748