MESOSCALE PRECIPITATION DISCUSSION 0332
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
853 PM EDT THU AUG 28 2014
 
AREAS AFFECTED...PORTIONS OF IA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 290052Z - 290652Z
 
SUMMARY...THUNDERSTORMS HAVE BEEN RECENTLY DEVELOPING ACROSS
SOUTHWEST IA, WHICH ARE EXPECTED TO EXPAND IN COVERAGE AN
INTENSITY.  RAINFALL RATES UP TO 2.5" AN HOUR ARE POSSIBLE, WHICH
COULD LEAD TO FLASH FLOODING.

DISCUSSION...THUNDERSTORMS HAVE BEGUN TO DEVELOP NEAR THE
INTERSECTION OF AN OUTFLOW BOUNDARY WITH A STATIONARY FRONT, NEAR
AND NORTHEAST OF A SURFACE LOW PER THE 00Z OBSERVATIONS.  THE
LATEST SPC MESOANALYSIS INDICATES CAPE VALUES IN THE 3000-4000
J/KG RANGE IN AN AREA OF 850 HPA INFLOW OF AROUND 30 KTS.  THE
LOW-LEVEL FLOW HAS STARTED TO SLOWLY BACK DUE TO A SHORTWAVE
MOVING BY TO THE WEST ACROSS NE WHICH IS BEGINNING TO TAP INFLOW
FROM THE UNSTABLE WARM SECTOR NEAR THE KS/MO BORDER.  WET BULB
ZEROES FROM AREA SOUNDINGS ARE ROUGHLY 12,500 FEET HIGH, IMPLYING
WARM RAIN PROCESSES COULD BE AT WORK OVERNIGHT.  WHEN COMBINED
WITH PRECIPITABLE WATER VALUES OF ~2", THE STAGE HAS BEEN SET FOR
THE WET MULTICELL ENVIRONMENT.

THE FORECAST IS FOR THE CONVECTION TO CONTINUE MOVING
EAST-NORTHEAST TO NORTHEAST ACROSS IA, AS 850 HPA INCREASES AND
BROADENS STATEWIDE OVER THE NEXT SEVERAL HOURS, WHICH COULD CAUSE
BACKBUILDING/TRAINING OF CONVECTION.  CONVECTION IS EXPECTED TO BE
INCREASINGLY ELEVATED IN NATURE, TRAVELING ALONG AN AXIS OF
MOISTURE ASSOCIATED WITHIN THE PARENT CYCLONE'S WARM CONVEYOR
BELT.  THE MESOSCALE QPF GUIDANCE IS UNANIMOUS IS SHOWING LOCAL
AMOUNTS OF 2-4", WHICH COULD CAUSE FLASH FLOODING, PARTICULARLY
ACROSS SATURATED AREAS OF SOUTHERN IA.  FLASH FLOODING IS
CONSIDERED POSSIBLE.

ROTH

ATTN...WFO...DVN...ARX...DMX...EAX...FSD...OAX...

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

LAT...LON   42219089 41109251 40539418 40439519 40819581 41649585
            42549511 43259366 43469143 42219089