MESOSCALE PRECIPITATION DISCUSSION 0277
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
207 AM EDT SAT AUG 16 2014
 
AREAS AFFECTED...NORTHERN MO & SOUTHERN IA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 160607Z - 160907Z
 
SUMMARY...A CONVECTIVE AREA WITH AN ASSOCIATED MESOCYCLONE SHOULD
MAINTAIN A RISK OF FLASH FLOODING FOR ANOTHER FEW HOURS.

DISCUSSION...CONVECTION REMAINS WELL ELEVATED OVER A FRONTAL
BOUNDARY LYING ACROSS CENTRAL MO AND NORTHEAST KS AHEAD OF A WEAK
WAVE OF LOW PRESSURE.  RADAR IMAGERY APPEARS TO REVEAL A
MESOCYCLONE WITHIN THE THUNDERSTORM AREA, AND CLOUD TOPS WITHIN
THE MINUTELY RAPID SCAN SATELLITE IMAGERY REACHED THEIR PEAK
COOLNESS ALONG THE IA/MO BORDER AT 0535Z.  UPSTREAM CAPES REMAIN
IN THE 500-1000 J/KG RANGE AND 850 HPA INFLOW HAS INCREASED TO 40
KTS.  COMBINED WITH PRECIPITABLE WATER VALUES OF 2"+, THE
THRESHOLD FOR THE WET MULTICELL ENVIRONMENT HAS JUST BEEN MET.

WHILE AVAILABLE MOISTURE AND 850 HPA INFLOW REMAIN SIGNIFICANT,
INSTABILITY UPSTREAM HAS BEEN FADING OVER THE PAST FEW HOURS AND
BECOMING FURTHER REMOVED FROM THE CONVECTION -- 500 J/KG MUCAPE IS
~80 MILES AWAY FROM THE CONVECTIVE AREA WHILE VALUES > 1000 J/KG
ARE 120 MILES DISTANT.  THE EMBEDDED MESOCYCLONE SHOULD KEEP
RAINFALL RATES UP FOR ANOTHER FEW HOURS BEFORE THE CONVECTIVE AREA
BECOMES LESS EFFICIENT FROM A CONVECTIVE STANDPOINT AND
INCREASINGLY STRATIFORM.  THE 18Z SSEO NEIGHBORHOOD PROBABILITIES
OF EXCEEDING THE THREE HOUR FLASH FLOOD GUIDANCE FALL BELOW 30% BY
09Z, WHICH IS USED AS THE TIME HORIZON OF THIS MPD.  UNTIL THEN,
2" AN HOUR RAIN RATES ARE POSSIBLE, WHICH COULD CAUSE FLASH
FLOODING.

ROTH

ATTN...WFO...LSX...DVN...DMX...EAX...OAX...

ATTN...RFC...MBRFC...NCRFC...

LAT...LON   39369262 39319142 40149104 40849125 41249188 41379366
            41139438 40649437 40609515 40509541 40369545 40039507
            39919448 39369262