MESOSCALE PRECIPITATION DISCUSSION 0228
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
758 PM EDT TUE JUN 16 2015
 
AREAS AFFECTED...SOUTHERN TO CENTRAL MO...SOUTHERN IL... 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 162357Z - 170457Z
 
SUMMARY...AN ORGANIZED AREA OF DEEP CONVECTION HAS SETTLED OVER
SECTIONS OF CENTRAL MO. THE NOCTURAL LLJ COUPLED WITH HIGHLY
ANOMALOUS MOISTURE IN PLACE WILL SUPPORT MAINTAINING HEAVY
RAINFALL OVER CENTRAL/SOUTHERN MO INTO SOUTHERN IL THROUGH AT
LEAST 05Z. 

DISCUSSION...AT 23Z...A WELL-DEFINED MOISTURE GRADIENT WAS
OBSERVED STRETCHING FROM WEST-CENTRAL MO EASTWARD TO JUST NORTH OF
ST. LOUIS MO AND INTO SOUTHEASTERN IL. CONVECTION THIS EVENING HAS
TENDED TO FOCUS ALONG AND SOUTH OF THIS BOUNDARY WHERE
MOIST/UNSTABLE CONDITIONS HAVE PREVAILED. THE 23Z RAP OBJECTIVE
ANALYSIS PLACES AROUND 1000 TO 1500 J/KG OF MIXED-LAYER CAPE IN
THE PRESENCE OF ABOVE 2 INCH PWATS PER BLENDED-TPW DATA. THIS
COMBINATION SUPPORTS VERY EFFICIENT HEAVY RAINFALL PROCESSES. AT
THIS TIME...THE COOLEST CLOUD TOPS AROUND -60C WERE OBSERVED IN
THE STRONGEST THUNDERSTORMS DELINEATED IN RED ON THE ACCOMPANYING
GRAPHIC. STORM MOTION VECTORS HAVE CARRIED CELLS TOWARD THE EAST
WITH SOME REGENERATION NOTED ON THE NOSE OF THE LOW-LEVEL INFLOW.
THE 23Z RAP SUGGESTS THIS FLOW SHOULD INCREASE INTO THE OVERNIGHT
HOURS AS THE NOCTURNAL LLJ BRINGS 850-MB WINDS INTO THE 20 TO 25
KNOT RANGE BY ~04Z. THIS IN PART SHOULD HELP MAINTAIN A HEALTHY
AXIS OF DEEP CONVECTION INTO THE OVERNIGHT HOURS...PARTICULARLY AS
ELEVATED INSTABILITY  UPWARDS OF 1000 J/KG REMAINS PRESENT.

THE PAST FOUR CYCLES OF THE HRRR HAVE BEEN QUITE CONSISTENT IN
PAINTING A HEAVY AXIS OF RAINFALL SOMEWHERE ACROSS SOUTHEASTERN TO
EAST-CENTRAL MO. THE 23Z HRRR INDICATES THESE HIGHER AMOUNTS
APPROACHING THE ST. LOUIS METRO AREA WHERE 2 TO 4 INCHES ARE BEING
FORECAST THROUGH 06Z. REGARDLESS IF THIS MODEL VERIFIES...A FLASH
FLOOD THREAT DOES EXIST ACROSS THE ENTIRE REGION BASED ON CURRENT
RADAR/SATELLITE TRENDS AND HIGH-RESOLUTION MODEL OUTPUT.  


RUBIN-OSTER

ATTN...WFO...EAX...ILX...LSX...PAH...SGF...

ATTN...RFC...ABRFC...LMRFC...MBRFC...NCRFC...OHRFC...

LAT...LON   39279040 39078887 38358802 37438809 37158913 
            37139060 36669216 36619327 36869411 37879422 
            38709298 39149173