MESOSCALE PRECIPITATION DISCUSSION 0123
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
653 PM EDT SAT JUN 14 2014
 
AREAS AFFECTED...SRN MN...WRN IA...SE SD...ERN NE 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 142229Z - 150414Z
 
SUMMARY...MODEL AGREEMENT IS STRONG IN PREDICTING A PROLONGED
PERIOD OF TRAINING ECHOES...AND SWATHS OF 1 TO 3 INCH...LOCALLY
GREATER...RAINFALL THROUGH 05Z. FLASH FLOODING IS
LIKELY...ESPECIALLY WHERE FLASH FLOOD GUIDANCE WAS PARTICULARLY
LOW ALONG THE IA/MN BORDER AND NORTHWARD INTO MN.

DISCUSSION...EARLY EVENING THUNDERSTORMS WILL BE CONCENTRATED
NORTH OF A SURFACE OUTFLOW BOUNDARY AND MID LEVEL CAP. INITIATION
OF NEAR-SURFACE BASED STORMS IS ALSO EXPECTED OVER NE...BUT
JUDGING BY SATELLITE AND HRRR RUNS THIS MAY WAIT FOR DEEPER ASCENT
TO ARRIVE FROM THE HIGH PLAINS. 

MEANWHILE THE RAP FORECASTS DEEP LAYER OMEGA TO INCREASE AND
PERSIST IN THE OUTLINED AREA AS DIFLUENT UPPER FLOW AND BROAD
FRONTOGENESIS DEVELOP. GIVEN THAT CELLS WILL BE ROOTED ALOFT AS
THEY LIFT NORTHWARD...UPSCALE GROWTH AND EASTWARD PROPAGATION MAY
BE DELAYED...RESULTING IN A PROLONGED PERIOD OF TRAINING FROM
SOUTHWEST TO NORTHEAST. MIXED LAYER CAPE OF 1500 J/KG NEAR THE
OUTFLOW BOUNDARY DECREASES GRADUALLY TO THE NORTH...BUT MUCAPE
VALUES WILL INCREASE TO AT LEAST 750 J/KG TOWARD CNTRL/ERN MN
THROUGH A COMBINATION OF STRENGTHENING LOW LEVEL WINDS AND DEEP
ASCENT. MODELS PREDICT PW VALUES UP TO 1.75 INCHES...BUT THIS MAY
FOLLOW THE CONVECTIVE OVERTURNING...WHILE INITIAL BACKGROUND
VALUES ARE CLOSER TO 1.50 INCHES. WITH SOME HAIL
INVOLVEMENT...EXPECT RAIN RATES UP TO 1.5 INCH/HR ON AVERAGE...BUT
LOCAL ACCUMULATIONS EXCEEDING 3 AND MAYBE 4 INCHES VIA TRAINING.

NORTHEAST NE AND AREAS FARTHER SOUTH IN IA WILL LIKELY BECOME MORE
OF A CONCERN BY LATE EVENING AS THE CAP ERODES IN THIS CAPE-RICH
ENVIRONMENT AND THE LOW LEVEL JET INCREASES TO 55 KT...YIELDING
HIGHLY ANOMALOUS MOISTURE FLUX...5 STANDARD DEVIATIONS...PER THE
GEFS STANDARD ANOMALIES.

BURKE

ATTN...WFO...MPX...DMX...FSD...OAX...

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

LAT...LON   45569481 44729593 43509691 42289787 41549743 41639573
            42639415 43439343 44229310 44869303 45269319 45579370
            45719428 45569481