MESOSCALE PRECIPITATION DISCUSSION 0359
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1012 PM EDT MON JUN 25 2018

AREAS AFFECTED...SOUTHERN IL...FAR SOUTHWEST IN...FAR NORTHWEST KY

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

VALID 260210Z - 260600Z

SUMMARY...SLOW-MOVING SHOWERS AND THUNDERSTORMS OVER THE NEXT FEW
HOURS WILL POSE A THREAT FOR SOME FLASH FLOODING.

DISCUSSION...RADAR IMAGERY SHOWS A RELATIVELY SMALL CLUSTER OF
HEAVY SHOWERS AND THUNDERSTORMS ATTEMPTING TO EXPAND IN COVERAGE
OVER AREAS OF SOUTHERN IL. THE ACTIVITY IS FOCUSING WITHIN A BROAD
WARM ADVECTION PATTERN JUST NORTH OF A QUASI-STATIONARY FRONT AND
AHEAD OF A DEEP LAYER CLOSE LOW OVER THE MIDWEST.

THE CONVECTION OVER THE NEXT FEW HOURS MAY ATTEMPT TO EXPAND A BIT
MORE IN COVERAGE AS THE SOUTHWEST LOW LEVEL FLOW INCREASES A BIT
AND OVERRUNS THE AFOREMENTIONED BOUNDARY WHILE THE REGION ALSO
BEGINS TO SEE AT LEAST MODEST HEIGHT FALLS ASSOCIATED WITH THE
MIDWEST CLOSED LOW. UPPER JET SUPPORT IS QUITE WEAK...BUT
INSTABILITY IS QUITE PLENTIFUL WITH MLCAPE VALUES ALONG THE FRONT
OF 2000 TO 2500 J/KG. A MODEST UPTICK IN LOW LEVEL JET ENERGY
SHOULD TEND TO AT LEAST SUSTAIN THE ONGOING ACTIVITY NEAR THE
FRONT AS IT ADVANCES VERY SLOWLY OFF TO THE EAST...AND THERE WILL
BE SOME POTENTIAL FOR AN EXPANSION OF ACTIVITY FARTHER DOWNSTREAM
ALONG AND JUST NORTH OF THE FRONT INVOLVING PARTS OF FAR SOUTHWEST
IN AND NORTHWEST KY.

THE MOST RECENT HIRES MODEL GUIDANCE LED BY THE HRRR SUGGESTS A
LOCALIZED STRIPE OF 3 TO 4 INCHES OF RAIN OVER THE NEXT FEW HOURS
ACROSS AREAS OF SOUTHERN IL. AREAS OF FAR SOUTHWEST IN AND FAR
NORTHWEST KY WILL ALSO NEED TO BE MONITORED BASED THE LATEST
CONVECTIVE TRENDS. SOME FLASH FLOODING WILL BE POSSIBLE GIVEN THE
EXPECTED AMOUNTS.

ORRISON

ATTN...WFO...ILX...IND...LMK...LSX...PAH...

ATTN...RFC...LMRFC...NCRFC...OHRFC...

LAT...LON   38628873 38468782 38138693 37638698 37648787
            37798850 38068975 38248990 38568968 38618929