MESOSCALE PRECIPITATION DISCUSSION 0378
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
704 AM EDT WED SEP 17 2014
 
AREAS AFFECTED...WESTERN MO & NORTHWEST AR 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 171104Z - 171604Z
 
SUMMARY...A BROADENING BAND OF BACKBUILDING AND TRAINING
THUNDERSTORMS ARE EXPECTED TO DROP 2-4" OF RAIN IN A SHORT TIME
FRAME.  FLASH FLOODING IS CONSIDERED POSSIBLE HERE.

DISCUSSION...THUNDERSTORMS HAVE DEVELOPED OVER THE PAST FEW HOURS
WITHIN A WARM ADVECTION REGIME, FOCUSED JUST POLEWARD OF A
STATIONARY FRONT DUE TO SOME CIN ALONG THE BOUNDARY.  INFLOW AT
850 HPA IS MODERATELY BROAD AND ON THE ORDER OF 25-30 KTS ACROSS
THE REGION.  MOST UNSTABLE CAPE VALUES OF 1000-2000 J/KG LIE
UPSTREAM ACROSS EASTERN KS AS WELL AS SOUTHWEST MO.  PRECIPITABLE
WATER VALUES ARE JUST OVER 1.5" PER RECENT RAP GUIDANCE, WHICH
SUPPORTS HOURLY RAIN RATES UP TO 2".  THE CONDITIONS HAVE BEEN MET
FOR THE WET MULTICELL ENVIRONMENT.

THE FORECAST IS FOR THE BAND TO EXTEND FARTHER SOUTHEAST WITH
TIME, POSSIBLY INTO NORTHWESTERN AR, AS THE MAGNITUDE OF THE 850
HPA INFLOW REMAINS CONSTANT WHILE SLOWLY SHIFTING SOUTHWARD PER
RECENT RAP GUIDANCE.  CAPE VALUES SHOULD BE SUFFICIENT TO MAINTAIN
CONVECTION WELL INTO THE MORNING.  PROPAGATION TO THE SOUTHEAST
WITH TIME COULD CAUSE A PERIOD OF TRAINING CONVECTION OVER THE
NEXT SEVERAL HOURS DUE TO CELL BACKBUILDING.  OUR HYPOTHESIS IS
THAT MIXING CAUSED BY DAYTIME HEATING COULD DISRUPT THIS ACTIVITY
BY 16Z, BUT IT COULD PERSIST LONGER.  THE MESOSCALE GUIDANCE
ADVERTISES LOCAL AMOUNTS OF 2-4" IN THIS REGION, CLOSE TO THE
THREE HOUR FLASH FLOOD GUIDANCE VALUES, THOUGH THEIR PLACEMENT
SHOWS A BIT OF DISPERSION.  FLASH FLOODING IS CONSIDERED POSSIBLE
HERE.

ROTH

ATTN...WFO...EAX...LSX...LZK...MEG...SGF...TOP...TSA...

ATTN...RFC...ABRFC...LMRFC...MBRFC...

LAT...LON   39849437 38129219 36549117 35839213 36099360 
            37659480 39669552