MESOSCALE PRECIPITATION DISCUSSION 0753
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
913 PM EDT TUE OCT 25 2016
 
AREAS AFFECTED...NRN IA/SRN MN 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 260112Z - 260712Z
 
SUMMARY...FLASH FLOODING IS EXPECTED TO DEVELOP ACROSS THE MN/IA
BORDER WITH A PEAK IN THE 04-07Z TIME FRAME. RAINFALL RATES OF 1
TO 1.5 IN/HR SHOULD CONTRIBUTE TO 3-4 INCH MAXIMUM RAINFALL TOTALS
THROUGH 07Z WITH THE FLASH FLOOD THREAT POSSIBLY EXTENDING BEYOND
07Z.

DISCUSSION...WATER VAPOR SATELLITE IMAGERY AS OF 01Z SHOWED A
MID-UPPER LEVEL SHORTWAVE LOCATED OVER CNTRL SD/NE...MOVING TOWARD
THE EAST. REGIONAL RADAR IMAGERY SHOWED A NW-SE AXIS OF ELEVATED
CONVECTION OCCURRING 150-200 MILES NORTHEAST OF A SURFACE WARM
FRONT CROSSING THE MID-MISSOURI RIVER VALLEY...OR JUST AHEAD OF AN
850 MB WARM FRONT BISECTING IOWA FROM NW TO SE. THE 00Z SOUNDING
FROM DVN SHOWED POOR LAPSE RATES ABOVE AN INVERSION LOCATED NEAR
800 MB...BUT THE OAX SOUNDING SHOWED 8 C/KM IN THE 700-500 MB
LAYER. THIS WAS CONTRIBUTING TO AN ESTIMATED MUCAPE BETWEEN 500
AND 1500 J/KG OVER ERN NE...WITHIN THE BEST AXIS OF 850 MB WINDS
OF 30-40 KTS CONFIRMED BY AREA VAD WIND PLOTS. 

WHILE PRECIPITABLE WATER VALUES OF ONLY 1.25 INCHES WERE GREATEST
OVER OMA...GIVEN THE TIME OF YEAR...THESE VALUES EQUATE TO
STANDARDIZED ANOMALIES OF +2 TO +3. AS THE AFOREMENTIONED
SHORTWAVE APPROACHES IN THE 04-07Z TIME FRAME...INCREASED LOW
LEVEL FLOW WILL HELP TO TRANSPORT MOISTURE NORTHWARD IN THE
PRESENCE OF INCREASING UPPER DIFFLUENCE. 

WHILE RECENT HI-RES MODELS SEEM TO A HAVE A DECENT HANDLE ON THIS
SETUP...THEY HAVE BEEN UNDERDONE WITH ONGOING RAINFALL COVERAGE
OVER THE CNTRL IA/MN BORDER. GIVEN THE EXPECTED INCREASE IN
FAVORABLE PARAMETERS LATER TONIGHT...MODELS MAY BE UNDERPLAYING
THE MAGNITUDE OF THE EVENT. ALTHOUGH LIMITING FACTORS ARE WEAK
INSTABILITY AND SOMEWHAT LIMITED MOISTURE...RAINFALL RATES TO 1 TO
1.5 IN/HR ARE EXPECTED. WHERE UNIDIRECTIONAL FLOW SETS UP TRAINING
ECHOES...FLASH FLOODING WILL BE POSSIBLE.

OTTO

ATTN...WFO...ARX...DMX...FSD...MPX...

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

LAT...LON   44489339 43829179 43209114 42789175 42869322 
            43479539 44379544