MESOSCALE PRECIPITATION DISCUSSION 0500
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1156 AM EDT FRI SEP 18 2015
 
AREAS AFFECTED...SERN KANSAS INTO SRN IOWA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 181551Z - 182100Z
 
SUMMARY...TRAINING OF HEAVY RAINFALL FROM SERN KANSAS INTO SRN
IOWA APPEARS LIKELY INTO MID-AFTERNOON WITH POSSIBLE FLASH
FLOODING. RAINFALL RATES OF 1-2 IN/HR ARE EXPECTED WITH 6 HOUR
TOTALS OF 3-4 INCHES.

DISCUSSION...AS OF 15Z...TRENDS IN REGIONAL RADAR IMAGERY SHOWED
INCREASING CONVECTION FROM WRN OKLAHOMA INTO SERN NEBRASKA AND SRN
IOWA. ACTIVITY LOCATED SOUTH OF A STATIONARY BOUNDARY...ANALYZED
FROM E-CNTRL KANSAS INTO SERN IOWA...APPEARS TO BE TIED TO BROAD
ISENTROPIC LIFT EXTENDING BACK INTO NWRN TEXAS. AN OUTFLOW
BOUNDARY TIED TO THE KANSAS CONVECTION MAY CONTINUE TO BE A FOCUS
FOR ADDITIONAL THUNDERSTORMS INTO THE EARLY AFTERNOON GIVEN THE
GROWING TEMPERATURE GRADIENT ACROSS THE BOUNDARY AND CONTINUED
FOCUS OF LOW LEVEL MOISTURE. THE ACTIVITY DEVELOPING FROM ERN
NEBRASKA INTO SRN IOWA IS MORE DIRECTLY TIED TO ASCENT AHEAD OF AN
APPROACHING MID-LEVEL SHORTWAVE CURRENTLY MOVING INTO WRN SOUTH
DAKOTA/NEBRASKA. AN ANOMALOUS MOISTURE AXIS EXTENDED SW TO NE
ACROSS THE MPD THREAT AREA...AS REFERENCED IN RECENT SAB SPENES
MESSAGE FROM 1448Z...IS NOT FORECAST TO MOVE THROUGH MID-AFTERNOON.

A WELL DEFINED FRONTAL WAVE OVER CNTRL KANSAS AT 15Z IS EXPECTED
TO MOVE TO THE IOWA/MISSOURI BORDER BY 21Z. THE BEST LOW LEVEL
INFLOW...BETWEEN 850-700 MB...OF 30-40 KTS WILL LIKELY FOLLOW
AHEAD OF THE SURFACE LOW HELPING DRIVE THE BEST POTENTIAL FOR
TRAINING WITH UNIDIRECTIONAL FLOW THROUGHOUT THE CLOUD BEARING
LAYER. IN ADDITION...INCREASED UPPER DIFFLUENCE/DIVERGENCE SHOULD
START TO APPROACH SRN IOWA AND NRN MISSOURI BY 20Z AHEAD OF THE
APPROACHING SHORTWAVE MOVING INTO THE CNTRL/NRN PLAINS. THERE ARE
UNCERTAINTIES WITH THE AMOUNT OF AVAILABLE INSTABILITY TU SUPPORT
HEAVIER RAINFALL RATES BY EARLY AFTERNOON NEAR THE IOWA
BORDER...BUT THE ENTIRE MPD THREAT AREA SEEMS TO HAVE HAVE A FLASH
FLOOD THREAT THROUGH AT LEAST 21Z.

RECENT HI-RES MODEL RUNS HAVE BEEN POOR AT CONVECTIVE EVOLUTION
THIS MORNING SO CONFIDENCE IN THE FLASH FLOOD THREAT IS ONLY
MODERATE.

OTTO

ATTN...WFO...DMX...DVN...EAX...ICT...ILX...LSX...OAX...SGF...
TOP...

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

LAT...LON   41219334 41049142 40549070 40079078 39109220 
            38069417 37329528 37159663 37279713 37839749 
            38949674 40109545 41119493