MESOSCALE PRECIPITATION DISCUSSION 0377
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
905 PM EDT THU JUN 28 2018

AREAS AFFECTED...SOUTHEASTERN MO/SLIVER OF SOUTHWESTERN IL...

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

VALID 290104Z - 290434Z

SUMMARY...CONVECTION CONTINUES TO THRIVE WITHIN A VERY MOIST AND
BUOYANT AIR MASS ACROSS SOUTHERN MO. THE LATEST GOES-16 MESOSECTOR
1-MINUTE IMAGERY SHOWS BACKBUILDING SOUTHWEST OF ST. LOUIS WHILE
THE REMAINDER OF THE MCS HAS CONTINUED TO BE PROGRESSIVE. THIS
WESTERN FLANK OF THE CONVECTIVE SYSTEM WILL REMAIN A THREAT FOR
FLASH FLOODING THE NEXT FEW HOURS UNTIL IT CAN FORWARD PROPAGATE
AS WELL.

DISCUSSION...WITH A MEAN UPPER RIDGE ESTABLISHED ACROSS THE
SOUTH-CENTRAL U.S...A SERIES OF CONVECTIVE COMPLEXES CONTINUE TO
CIRCULATE CLOCKWISE AROUND THE RING OF FIRE. LOW-LEVEL MOISTURE
CONTENT WITHIN THE INFLOW REGION IS QUITE IMPRESSIVE AS A NUMBER
OF 80 DEGREE PLUS DEW POINTS HAVE BEEN OBSERVED ACROSS
NORTHEASTERN AR/SOUTHEASTERN MO. BASED ON THE 00Z RAP THETA-E
OBJECTIVE ANALYSIS...THIS CONVECTIVE COMPLEX HAS GENERALLY
POSITIONED ITSELF ALONG A RATHER SHARP THETA-E GRADIENT. THE RAP
FORECAST SHOWS A DECREASE IN THIS GRADIENT GIVEN THE REDUCTION IN
SURFACE HEATING WITH A GENERAL SOUTHWARD SHIFT OF THIS CONVERGENCE
AXIS. VERY LITTLE CAM GUIDANCE SHOW ANY REFLECTION OF THIS
EVOLUTION SO THIS IS GENERALLY BASED ON GOES-16 IMAGERY AND
AVAILABLE SURFACE DATA. BASED ON LOCAL STORM REPORTS...THIS
THUNDERSTORM COMPLEX HAS A HISTORY OF PRODUCING VERY HEAVY
RAINFALL. AROUND 0030Z...MADISON COUNTY OVER SOUTHWESTERN IL
REPORTED 2.11 INCHES OF RAIN IN 75 MINUTES. WILL MAINTAIN A THREAT
FOR FLASH FLOODING THROUGH AT LEAST 04-05Z.

RUBIN-OSTER

ATTN...WFO...LSX...MEG...PAH...SGF...

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

LAT...LON   38469058 37838938 36628932 36468998 36619084
            37039130 38289132