MESOSCALE PRECIPITATION DISCUSSION 0124
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1026 PM EDT SAT JUN 14 2014
 
AREAS AFFECTED...ERN NE...WRN IA...NW MO...SE SD 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 150224Z - 150724Z
 
SUMMARY...MODERATE INSTABILITY AND STRONGLY FOCUSED LOW LEVEL
INFLOW WILL YIELD EXCESSIVE RAINFALL IN A SHORT TIME OVER PARTS OF
NE/IA. THE HRRR HAS SHOWN A CONSISTENT SIGNAL FOR PARTICULARLY
HEAVY RAINS THROUGH 07Z DURING THE PEAK PHASING OF THE LOW LEVEL
JET WITH MID LEVEL FORCING FOR VERTICAL MOTION.

DISCUSSION...SURFACE BASED CONVECTION IS LIKELY TO REMAIN FOCUSED
INITIALLY OVER NORTHEAST NE AND ADJACENT PORTIONS OF SD/IA.
ACCOUNTING FOR LONG RANGE FROM KFSD AND KOAX ALONG WITH DUAL POL
HANDLING HAIL IMPERFECTLY...CONSERVATIVE ESTIMATES SUGGEST RAIN
RATES NEAR 2.5 INCHES/HR AT TIMES. BRIEFLY HEAVIER RATES ARE
POSSIBLE...NOTING THE REPORT OF 1.99 INCHES IN 30 MINUTES OUT OF
SIOUX CITY IA VIA WFO SIOUX FALLS. CONVECTION FARTHER SOUTH HAD
SHOWN MORE DISCRETE CHARACTER...BUT IS LIKELY TO GROW UPSCALE
BETWEEN 02-05Z AS THE LOW LEVEL JET INTENSIFIES AND MID LEVEL
ASCENT INCREASES FROM THE WEST...THUS BREACHING THE CAP IN A MORE
ORGANIZED FASHION.

THE FLEDGLING MCS IN NORTHEAST NE WAS LAYING OUT AN EAST-WEST
BOUNDARY AS OF 0215Z...CAPABLE OF INTERCEPTING THE 850 INFLOW AND
LEADING TO TRAINING OF CELLS. THESE WILL CARRY A SEVERE WEATHER
THREAT PER SPC...BUT ALSO VERY HEAVY RAIN. NUMEROUS CONSECUTIVE
RUNS OF THE HRRR FORECAST THE EMPHASIS TO SHIFT WITH TIME TOWARD A
NEWLY DEVELOPING MCS NEAR I-80 BETWEEN HASTINGS AND OMAHA.
ESPECIALLY CONCERNING ARE THE POCKETS OF 5+ INCHES OF RAIN THAT
APPEARED IN SEVERAL RUNS. THIS SEEMS VERY PLAUSIBLE AS A 50-60 KT
LLJ WILL YIELD 850 MB MOISTURE TRANSPORT 5 DEVIATIONS ABOVE
AVERAGE VIA THE GEFS ANOMALIES...WHILE BACKING MID LEVEL WINDS
AHEAD OF THE UPPER SHORTWAVE YIELD BACKING CELL MOTIONS AND
REDEVELOPMENT UPWIND OF ANY ADVANCING MCS.

BURKE

ATTN...WFO...DMX...EAX...FSD...OAX...GID...

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

LAT...LON   43029509 43009628 42559741 41559821 40939854 40309859
            40049757 40199578 40849462 41449418 42359411 42809450
            43029509