MESOSCALE PRECIPITATION DISCUSSION 0336
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
715 PM EDT SUN AUG 31 2014
 
AREAS AFFECTED...SERN NEBRASKA / KANSAS INTO NWRN MISSOURI AND
IOWA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 312314Z - 010514Z
 
SUMMARY...THE THREAT FOR FLASH FLOODING WILL INCREASE PAST THROUGH
05Z WITH REPEATING CELL MOTIONS POSSIBLY ALLOWING 3-6 INCHES IN
SOME LOCATIONS WITH 1-2 IN/HR RAINFALL RATES FROM CNTRL AND ERN
KANSAS. FARTHER NORTH...PROGRESSIVE STORM MOTIONS WITH HIGH
RAINFALL RATES SHOULD ALLOW FOR A LOWER END FLASH FLOOD THREAT.

DISCUSSION...23Z SURFACE OBSERVATIONS PLACED A PROGRESSIVE COLD
FRONT ACROSS ERN NEBRASKA INTO NRN AND WRN KANSAS WITH A 1001 MB
WAVE 40 MI W OF OMA. EXTENDING SEWD FROM THE LOW WAS A
DIFFERENTIAL HEATING BOUNDARY WITH SURFACE TEMPERATURES IN THE
MID-UPPER 90S ACROSS CNTRL AND ERN KANSAS WHILE DEWPOINTS
GENERALLY LESS THAN 70 F. THIS INITIALLY DRY LOW LEVEL LAYER
SHOULD ALLOW FOR AN OUTFLOW BOUNDARY TO SET UP ACROSS CNTRL/ERN
KANSAS FROM A LINE OF STORMS CURRENTLY IN PLACE AHEAD OF THE COLD
FRONT. SHORT TERM RAP/HRRR FORECASTS SHOW 850 MB FLOW INCREASING
TO NEAR 50 KTS BY 03Z ACROSS ERN KANSAS WITH SOME VEERING TOWARD
THE SOUTHWEST. 

HI-RES MODEL GUIDANCE HAS BEEN UNANIMOUS IN A HEAVY RAIN SIGNAL
OVERNIGHT BUT SOME DIFFERENCES IN PLACEMENT EXIST WITH SOME
SHOWING A GREATER FOCUS INTO IOWA VERSUS OTHERS IN KANSAS...SUCH
AS THE HRRR. IT IS EXPECTED THAT THE GREATER THREAT WILL BE ACROSS
KANSAS AS REPEATING CELLS ARE EXPECTED TO DEVELOP OVERNIGHT WITH
AN INCREASED MAGNITUDE OF THE LOW LEVEL JET WHICH WILL ADVECT IN
PWATS BETWEEN 1.5 TO 2.0 INCHES FROM THE SOUTH ATOP A CONVECTIVELY
INDUCED BOUNDARY. MEANWHILE...STORMS TO THE NORTH ACROSS IOWA
SHOULD EXHIBIT RAINFALL RATES OF 1-2 IN/HR BUT STAY MOSTLY
PROGRESSIVE WITH A LOWER END THREAT FOR FLASH FLOODING ACROSS THE
NRN PORTION OF THE THREAT AREA.

OTTO

ATTN...WFO...DMX...EAX...FSD...OAX...TOP...ICT...GID...DDC...

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

LAT...LON   38509444 37949611 38019817 38049911 38649931 39369853
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            40699292 38509444