MESOSCALE PRECIPITATION DISCUSSION 0357
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
239 AM EDT MON JUN 25 2018

AREAS AFFECTED...FAR SOUTHEAST MO...FAR SOUTHERN IL...SOUTHWEST
IN...WESTERN KY

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

VALID 250635Z - 251235Z

SUMMARY...HEAVY RAINFALL IS EXPECTED OVERNIGHT WITH CONCERNS FOR
SOME FLASH FLOODING GIVEN THE RISK OF CELL-MERGERS AND TRAINING.

DISCUSSION...A WELL-DEFINED MCV IS ADVANCING SLOWLY EAST ACROSS
SOUTHEAST IL CURRENTLY AND THERE HAS ALREADY BEEN SOME CONVECTION
FOCUSED AROUND THE SOUTHERN FLANK OF THE MCV WHICH HAS PROPAGATED
DOWNSTREAM ACROSS WESTERN/CENTRAL KY. THIS ACTIVITY THOUGH HAS
BEEN SHOWING EVIDENCE OF WEAKENING AS THE CLOUD TOPS HAVE BEEN
WARMING A BIT AND IT IS ALSO MOVING INTO AN AREA OF GREATER STATIC
STABILITY.

HOWEVER...OVER THE LAST HOUR...THERE HAS BEEN SOME CELL
REGENERATION OCCURING OVER PARTS OF FAR SOUTHEAST MO...AND THERE
WILL BE CONCERNS MOVING FORWARD THROUGH THE PREDAWN HOURS OF THERE
BEING A MORE SUBSTANTIAL AXIS OF CONVECTION REGENERATING ACROSS
AREAS OF SOUTHEAST MO...SOUTHERN IL AND EXTENDING BACK ACROSS
AREAS OF WESTERN KY. THIS IS EXPECTED TO BE FACILITATED BY AN
INCREASE IN CONFLUENT FLOW AROUND THE SOUTH SIDE OF THE MCV AND
INTO A WELL-DEFINED STATIONARY FRONT ORIENTED W/E ACROSS THE
REGION. AN INSTABILITY GRADIENT IS NOTED ALONG THE FRONT...WITH AS
MUCH AS 500 TO 1000 J/KG OF MUCAPE.

THE HIRES MODELS CONSENSUS LED BY THE 00Z NAM-CONEST/ARW/NMMB
SOLUTION AND MULTIPLE RUNS OF THE HRRR/HRRRX GUIDANCE ALL STRONGLY
SUPPORT AN AXIS OF HEAVY SHOWERS AND THUNDERSTORMS DEVELOPING OVER
THE NEXT COUPLE OF HOURS AND BECOMING ALIGNED WITH THE FRONT IN A
FASHION THAT STRONGLY FAVORS TRAINING.

THIS WILL FOSTER SOME LOCALLY VERY HEAVY RAINFALL POTENTIAL...AND
THE AFOREMENTIONED HIRES GUIDANCE DOES SUPPORT AS MUCH AS 3 TO 4
INCHES OF ADDITIONAL RAIN WITH PERHAPS SOME ISOLATED HEAVIER
TOTALS GOING THROUGH 12Z. GIVEN THE EARLIER RAINFALL...THE
ANTECEDENT CONDITIONS ARE RATHER WET...AND SO THESE ADDITIONAL
AMOUNTS MAY CAUSE SOME FLASH FLOODING.

ORRISON

ATTN...WFO...LMK...LSX...MEG...OHX...PAH...

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

LAT...LON   38168755 37948658 37158659 36758745 36638837
            36608980 36659037 36919072 37279072 37759001
            38108855