Flash Flood Guidance
Issued by NWS

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000
AWUS01 KWNH 041541
FFGMPD
ILZ000-MOZ000-IAZ000-041930-

MESOSCALE PRECIPITATION DISCUSSION 0421
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1140 AM EDT TUE AUG 04 2015

AREAS AFFECTED...NORTHERN MO...FAR SOUTHERN IA

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 041539Z - 041930Z

SUMMARY...HEAVY RAINFALL OVER PARTS OF FAR SOUTHERN NEB INTO
NORTHERN MO SHOULD LINGER INTO THE EARLY AFTERNOON BEFORE
GRADUALLY BE TAPERING OFF.

DISCUSSION...OVERALL CONVECTION HAS BEEN WEAKENING ACROSS THE AREA
DURING THE MORNING BUT A NARROW AREA OF SHOWERS AND THUNDERSTORMS
HAS MANAGED TO PERSIST FROM FAR SOUTHERN IA INTO NORTHERN MO
THROUGH 1515Z.  12Z UPPER AIR SHOWED THIS TO BE ROUGHLY COINCIDENT
WITH THE AXIS OF HIGHEST PRECIPITABLE WATER VALUES.

ONE HOUR RAFL AMOUNTS DERIVED FROM AREA 88D RADARS WERE ON THE
ORDER OF 1.5 TO 2 INCHES PER HOUR ACROSS THE NORTHERN TIER OF
COUNTIES IN MISSOURI.  FLASH FLOOD GUIDANCE HERE WAS ON THE ORDER
OF 2 TO 2.5 INCHES PER 3 HOURS...HAVING LOWERED AS A RESULT OF
MODERATE TO HEAVY RAINFALL OVERNIGHT. THE LOWER FFG VALUES WILL
MAKE IT EASIER FOR FOR RAFL TO EXCEED FFG IN THIS AREA.
ELSEWHERE...FFG VALUES WERE ON THE ORDER OF 2 TO 2.5 INCHES PER 3
HOURS.

CONSIDERING THAT IR SATELLITE IMAGERY STILL SHOWED COLD CLOUD TOPS
STRADDLING THE IA/MO BORDER AS OF 15Z...THINK THAT LOCALIZED
MODERATE TO HEAVY RAINFALL WILL CONTINUE HERE IN THE SHORT TERM
WITH A RESULTING THREAT OF FLASH FLOODING.

HOWEVER...CONVECTIVE ALLOWING HI RES MODELS STILL SUGGEST THAT THE
LONGER TERM TREND IS FOR CONVECTION TO WEAKEN AS THE HIGHEST
PRECIPITABLE WATER VALUES BEGIN TO BE SHUNTED TO THE SOUTH OF THE
AREA.

FOR THOSE REASONS...EXPECTATIONS ARE THAT FLASH FLOOD THREAT WILL
LINGER INTO THE AFTERNOON FOLLOWED BY A DIMINISHING THREAT.

BANN

...PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...DMX...DVN...EAX...LSX...

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

LAT...LON   40989464 40939346 40689208 39769127 39179156
            39799361 39919406 40229487 40669489 40879484




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