MESOSCALE PRECIPITATION DISCUSSION 0281
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
808 PM EDT SAT AUG 16 2014
 
AREAS AFFECTED...CENTRAL/EASTERN MO...WESTERN/SOUTHERN IL 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 170000Z - 170600Z
 
SUMMARY...SHOWERS AND THUNDERSTORMS ARE BECOMING A BIT MORE
CONCENTRATED AND MAY BECOME MORE ORGANIZED THROUGH THE EVENING.
SOME FLASH FLOODING WILL BE POSSIBLE OVER THE NEXT FEW HOURS GIVEN
VERY INTENSE RAINFALL RATES.

DISCUSSION...THE LATEST IR SAT IMAGERY SHOWS SOME EXPANSION OF
COLD-TOPPED CONVECTION OVER FAR NERN MO VERY CLOSE TO AN AREA OF
SFC LOW PRESSURE ALONG WITH A SUPPORTING YET COMPACT MID LVL LOW
AND ASSOCD MCV. THE CONVECTION THEN STRETCHES SWWD IN A BKN
FASHION ACROSS CNTRL AND SWRN MO ALONG AND JUST AHEAD OF A COLD
FRONT. A VERY WARM AND MOIST BNDRY LYR IS PRESENT AHEAD OF THE
COLD FRONT...AND THERE IS SUFFICIENT INSTABILITY AND LARGE SCALE
FORCING FOR THE BKN CONVECTIVE ACTIVITY.

OVER THE NEXT FEW HOURS...THE LATEST HI-RES MODEL GUIDANCE
INCLUDING THE 22Z HRRR...18Z NAM-CONEST AND 12Z ARW SUGGEST
EXPANDING COVERAGE OF CONVECTION BETWEEN 00Z AND 06Z AS A LOW LVL
SWLY JET INCREASES TO 30 TO 40 KTS AND HELPS TO ENHANCE THE
TRANSPORT OF VERY MOIST/UNSTABLE AIR NEWD FROM THE SRN PLAINS.
MEANWHILE...THE AFOREMENTIONED MID LVL LOW CENTER/MCV WILL ADVANCE
ESEWD AND BE IN POSITION TO INTERSECT THIS FAVORABLE THERMODYNAMIC
FETCH. 

THE HRRR AND NAM-CONEST ARE THE WETTEST SOLNS...AND SUPPORT
RAINFALL AMTS BETWEEN 00Z AND 06Z OF 4 TO 6 INCHES WITH ISOLD
HEAVIER AMTS. THIS CANNOT BE RULED OUT GIVEN PWATS OF NEAR 2
INCHES AND THE EXPECTATION OF MORE CONCENTRATED AND SLOW-MOVING
CONVECTION THROUGH THE EVENING. RAINFALL RATES WILL BE QUITE
INTENSE...AND SO ANY CELL-MERGER ACTIVITY AND PERSISTENCE OF
CONVECTION WILL FOSTER AN ELEVATED CONCERN FOR FLASH FLOODING.
WILL CONTINUE TO MONITOR.

ORRISON

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

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

LAT...LON   38409302 38859240 39989147 40199055 39988950 39378865
            38628856 38128891 37708972 37299097 37149202 37249291
            37439334 37849343 38299307 38409302