MESOSCALE PRECIPITATION DISCUSSION 0128
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
724 PM EDT MON JUN 16 2014
 
AREAS AFFECTED...SE SD...SRN MN...ERN NE...NRN IA...SW WI 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 162322Z - 170422Z
 
SUMMARY...FLASH FLOODING WAS LIKELY ALREADY OCCURRING. THE EVENT
WILL EXPAND IN COVERAGE AND HAS POTENTIAL TO PRODUCE SOME HIGH
IMPACT FLASH FLOODING IN A FEW LOCATIONS...PARTICULARLY
SD...NE...IA.

DISCUSSION...A LENGTHY MCS WILL CONTINUE TO EXPAND EASTWARD DURING
RAPID NORTHWARD RETURN OF MOISTURE OVER IA/MN/WI. ALTHOUGH THIS
SYSTEM REPRESENTS A SEVERE WEATHER THREAT PER SPC FORECASTS...THE
STRONG UPDRAFTS AND MIGRATING PLUME OF 1.7 INCH PW WILL SUPPORT
INTENSE RAIN RATES ALONG THE LEADING EDGE. THIS WILL BE FOLLOWED
BY ADDITIONAL STRATIFORM RAIN AND EMBEDDED THUNDER
OVERNIGHT...OWING TO STOUT 850 MB INFLOW NORTH OF A RESERVOIR OF
MODERATELY UNSTABLE BUT CAPPED AIR.

OF GREATEST CONCERN IS THE WESTERN PORTION OF THIS AREA WHERE
ANTECEDENT RAINFALL OCCURRED IN RECENT DAYS AND WHERE THE MODEL
FLASH FLOOD SIGNAL IS GREATEST. RAP FORECASTS MID LEVEL ASCENT
BEING SUSTAINED AT AND BECOMING PHASED WITH THE LOW LEVEL JET AS
IT STRENGTHENS TO 50-PLUS KT BY 04Z. THOUGH CAPE/SHEAR
COMBINATIONS FAVOR SEVERE STORM MODES AND PROPAGATION...THE
FORCING MECHANISMS FAVOR OCCASIONAL QUASI-STATIONARY INITIATION
POINTS FOR NEW UPDRAFTS. ONE SUCH POINT SOUTH OF KFSD HAS PRODUCED
A BROAD SWATH OF RADAR-ESTIMATED RAINFALL OVER 5 INCHES. BASED ON
THE FEW OBSERVATIONS THUS FAR...AND CORRECTING FOR THE
ENVIRONMENT...WOULD EXPECT SOME ACCUMULATIONS APPROACHING 2 INCHES
PER HOUR AND EVENT TOTALS EXCEEDING 5 INCHES IN A MORE ISOLATED
FASHION THAN INDICATED BY DUAL POL ESTIMATES...BUT NONETHELESS
CAPABLE OF PRODUCING HIGHER END FLASH FLOODING. 

THE SORT OF STORM BEHAVIOR MAY DEVELOP ESE INTO NE/IA THIS EVENING
PER RECENT HRRR RUNS AND THE 12Z CANADIAN GEM REGIONAL MODEL WHICH
INDICATED MULTIPLE HEAVY SWATHS BASED ON COLD POOLS EMANATING FROM
THE MCS NORTH OF THE WARM FRONT AND THE SFC-BASED INITIATION
FARTHER SOUTH. WE MAY SEE A TRANSITION OF THE ORGANIZED FLOOD
THREAT TOWARD THE EAST AFTER 06Z WHEN MODELS SUGGEST THE
CONVECTION FEEDS BACK ONTO A SYNOPTIC SCALE SHORTWAVE HEADING
DOWNSTREAM.

BURKE

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

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

LAT...LON   42579061 42918986 43528984 44139080 44289285 44119462
            43689676 43149793 42579797 41809719 41519592 41739433
            42219257 42409135 42579061