MESOSCALE PRECIPITATION DISCUSSION 0451
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
625 PM EDT SAT JUL 14 2018

AREAS AFFECTED...FAR EASTERN MO...FAR WESTERN KY...IL

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

VALID 142225Z - 150225Z

SUMMARY...HEAVY SHOWERS AND THUNDERSTORMS WILL CONTINUE INTO THE
EVENING. VERY INTENSE RAINFALL RATES OF OVER 2 INCHES/HR WILL
LIKELY RESULT IN SOME ADDITIONAL FLASH FLOODING CONCERNS OVER THE
NEXT FEW HOURS.

DISCUSSION...THE LATEST GOES-16 CLEAN IR SATELLITE IMAGERY SHOWS A
SUBSTANTIAL AREA OF VERY COLD CONVECTIVE TOPS OVER WEST-CENTRAL
AND FAR SOUTHERN IL THAT IS GRADUALLY SHIFTING OFF TO THE EAST AND
SOUTHEAST. RADAR IMAGERY AND SURFACE OBSERVATIONS CONFIRM INTENSE
RAINFALL RATES OF AS MUCH AS 2 TO 3 INCHES/HR IN ASSOCIATION WITH
THE ACTIVITY.

THIS CONVECTION IS BEING FACILITATED BY A STRONGLY UNSTABLE
BOUNDARY LAYER THAT HAS NOSED UP ACROSS SOUTHERN AND WEST-CENTRAL
IL OUT AHEAD OF A WAVE OF LOW PRESSURE OVER NORTH-CENTRAL MO.
MLCAPE VALUES ARE LOCALLY AS HIGH AS 3000 TO 4000 J/KG AHEAD OF
THE WAVE...AND THIS WAVE IS ALSO ASSOCIATED WITH A LOW TO MID
LEVEL MCV WHICH IS PROVIDING NOT ONLY CONVERGENT FLOW BUT ALSO A
MORE DYNAMICAL FOCUS FOR CONVECTION. IT IS ALSO NOTED THAT THERE
IS SOME WEAK UPPER LEVEL JET FORCING OVER THE REGION ASSOCIATED
WITH VERY MODEST 250 MB RIGHT-ENTRANCE REGION JET DYNAMICS.

GIVEN PWATS OF 1.9 TO 2.1 INCHES BASED ON GPS-DERIVED
DATA...EXPECT THE RAINFALL RATES TO REMAIN VERY INTENSE AS
CONVECTION CONTINUES TO ORGANIZE OVER THE NEXT FEW HOURS GIVEN THE
LEVEL OF INSTABILITY.

EXPECT LOCALLY AS MUCH AS 3 TO 4 INCHES THROUGH MID-EVENING AS
SUGGESTED BY THE LATEST HRRR GUIDANCE...AND THIS WILL RESULT IN
SOME ADDITIONAL CONCERNS FOR FLASH FLOODING. CONDITIONS SHOULD
IMPROVE BY LATE EVENING AS THE INSTABILITY BECOMES INCREASINGLY
EXHAUSTED. WILL CONTINUE TO MONITOR.

ORRISON

ATTN...WFO...DVN...ILX...LOT...LSX...PAH...

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

LAT...LON   41649003 41638933 41218915 40958888 39818855
            38278789 37088793 36748891 37288968 38309030
            39679058 40989057