MESOSCALE PRECIPITATION DISCUSSION 0293
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
140 AM EDT TUE JUN 12 2018

AREAS AFFECTED...CTRL AND SE ILLINOIS...FAR SW INDIANA

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

VALID 120539Z - 121000Z

SUMMARY...THUNDERSTORMS WERE REDEVELOPING IN CENTRAL ILLINOIS
AROUND MIDNIGHT LOCAL TIME...ALMOST IMMEDIATELY ON TOP OF AREAS
THAT HAVE RECEIVED SIGNIFICANT RAINFALL IN THE PAST 24 HOURS.
THESE SLOW-MOVING STORMS MAY PRODUCE RAINFALL RATES OF 1-2 IN/HR
AND FLASH FLOODING GIVEN THE ALREADY SATURATED SOILS.

DISCUSSION...AN EARLIER MCS THAT MOVED FROM SOUTH-CENTRAL ILLINOIS
INTO SOUTHWEST INDIANA HAS BEGUN TO DECAY...AND THE ASSOCIATED MCV
WAS SLOWLY PUSHING EAST INTO NORTHERN KENTUCKY. DESPITE LIMITED
RECOVERY TIME IN THE WAKE OF THE EARLIER MCS... CONVECTIVE
INITIATION IS ALREADY TAKING PLACE ACROSS PORTIONS OF CENTRAL
ILLINOIS IN NEARLY THE SAME PLACE THAT THE EARLIER MCS TRACKED.
NSSL QUANTITATIVE PRECIPITATION ESTIMATES OVER THE PAST 24 HOURS
WERE GENERALLY IN EXCESS OF 2 INCHES...AND AS HIGH AS 5-6 INCHES
IN SOME AREAS. FLASH FLOOD GUIDANCE WAS UNDERSTANDABLY LOWER IN
THIS REGION WITH 3HR FFG BELOW 1.5 INCHES. THE COMBINATION OF
SLOW-MOVING CONVECTION DEVELOPING OVER ALREADY SATURATED SOILS
SHOULD CONTRIBUTE TO AN INHERENT THREAT OF FLASH FLOODING.

POTENTIALLY INCREASING THE THREAT WOULD BE BROAD LOW-LEVEL INFLOW
FROM THE WSW...WITH 850MB WINDS AROUND 20 KNOTS CERTAINLY ENOUGH
TO FOCUS CONVECTION OVER SEVERAL HOURS. THE INFLOW REGION WAS ALSO
CHARACTERIZED BY MUCAPE AROUND 1000-2000 J/KG...SUFFICIENT FOR
ORGANIZED CONVECTIVE CLUSTERS (AND KILX RADAR SHOWED THAT THIS MAY
ALREADY BE OCCURRING). RECENT RUNS OF THE HRRR AND THE 00Z HREF
SHOW POTENTIAL FOR BACKBUILDING OF THIS CONVECTION TO THE NNW
ALONG THE EFFECTIVE 850MB FRONT...WITH RAIN RATES IN THE 1-2 IN/HR
RANGE AND LOCALIZED RAINFALL TOTALS IN THE 2-4 INCH RANGE FOR
AREAS THAT RECEIVE MORE PERSISTENT THUNDERSTORMS.

LAMERS

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

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

LAT...LON   40528852 40108763 39478716 38398697 38068820
            38598916 39588998 40258968