MESOSCALE PRECIPITATION DISCUSSION 0165
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1042 AM EDT MON JUN 30 2014
 
AREAS AFFECTED...IA...ERN NE...SW WI 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 301441Z - 301941Z
 
SUMMARY...IT IS SYNOPTICALLY EVIDENT THAT RENEWED CONVECTION OVER
NE/IA WILL GROW UPSCALE AND PRODUCE ANOTHER BROAD SWATH OF
RAINFALL...SOME OF IT HEAVY. ANTECEDENT CONDITIONS...INTENSE RAIN
RATES...AND SOME LOCALIZED TRAINING WILL LIKELY YIELD FLASH
FLOODING.

DISCUSSION...SYNOPTIC DATA AND MODELS WERE SIGNALING THE
DEVELOPMENT OF AN ORGANIZED MCS. INCREASING MID LEVEL ASCENT WAS
ALREADY EVIDENCED BY GROUPS OF SUPERCELLS AND MULTICELLS IN ERN NE
AND WRN IA AT 14Z. ALTHOUGH HAIL WAS PRESENT...HEAVY RAIN WAS ALSO
FALLING...AND SHOULD BECOME MORE PREVALENT AS UPSCALE GROWTH
OCCURS. SIMULATED REFLECTIVITY FROM SEVERAL CONSECUTIVE RUNS OF
THE HRRR BUILD AN MCS BY 17-18Z AS SLACK 850 MB FLOW TURNS TO
25-30 KT INFLOW. DURING THE FORMATIVE STAGE...SMALL ANGLES BETWEEN
VARIOUS FORMS OF STORM MOTION SUGGEST WEST TO EAST TRAINING IS
LIKELY ON A LOCAL SCALE. ONCE FORMED...THE MCS WILL BECOME FORWARD
PROPAGATING...BUT RAIN RATES MAY ALSO INCREASE WITH THE
INVOLVEMENT OF MORE BOUNDARY LAYER AIR. INCREASED SOUTHERLY INFLOW
WILL PUMP INSTABILITY BACK INTO THE REGION AROUND HIGHWAY 20 IN
IOWA WHICH SAW 1-3 INCHES OF RAIN OVERNIGHT. FURTHERMORE...RAP
FORECASTS INDICATE THE PERIOD OF COUPLED LOW LEVEL INFLOW AND MID
LEVEL ASCENT SHOULD PERSIST WELL INTO THE AFTERNOON...SETTING UP
THE POSSIBILITY OF CELL REDEVELOPMENT AND TRAINING ON THE
SOUTHWEST FLANK OF NEW OUTFLOWS.

THE 12Z KOAX SOUNDING SAMPLED THE PRE CONVECTIVE ENVIRONMENT WITH
AN IMPRESSIVE PW OF 1.73 INCHES. THIS SUGGESTS SOME LOCATIONS WILL
SEE RAIN ACCUMLATE AT 2 INCHES PER HOUR. MODELS...THOUGH DIFFERING
IN PLACEMENT...PRODUCE POCKETS OF 3+ INCHES THROUGH 00Z.

BURKE

ATTN...WFO...DVN...ARX...DMX...FSD...OAX...

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

LAT...LON   42999364 42889512 42749612 42269745 41439716 40799570
            40709352 40999160 41569069 42289039 43009053 43429115
            43399192 42999364