Flash Flood Guidance
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000
AWUS01 KWNH 301108
FFGMPD
MOZ000-ARZ000-301500-

MESOSCALE PRECIPITATION DISCUSSION 0473
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
707 AM EDT SUN AUG 30 2015

AREAS AFFECTED...SOUTHWEST MO...NORTHWEST AR

CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY

VALID 301100Z - 301500Z

SUMMARY...PERSISTENT CLUSTER OF VERY HEAVY SHOWERS AND
THUNDERSTORMS ALONG THE MO/AR BORDER WILL CONTINUE TO FAVOR
SHORT-TERM FLASH FLOODING CONCERNS.

DISCUSSION...A CLUSTER OF NEARLY STATIONARY SHOWERS AND
THUNDERSTORMS IS PRODUCING VERY HEAVY RAINS OVER ESPECIALLY
EASTERN TANEY COUNTY IN MO...AND ADJACENT BOON COUNTY IN AR. THE
ACTIVITY IS FOCUSED JUST AHEAD OF A FRONTAL ZONE AND NORTHEAST OF
A WEAK WAVE OF LOW PRESSURE. WV IMAGERY INDICATES A WEAK SHORTWAVE
TROUGH ALSO DIGGING SOUTH INTO  SOUTHEAST KS/NORTHEAST OK AND
SOUTHWEST MO AND THIS PROVIDING A CONCENTRATED AREA OF DEEPER
LAYER FORCING TO PROMOTE CONVECTIVE DEVELOPMENT. ALSO FAVORING THE
CONVECTIVE DEVELOPMENT IS A POOL OF MODERATE INSTABILITY ORIENTED
ALONG THE BOUNDARY IN A MOSTLY ELEVATED FASHION...AND WITH SOME
VERY MODEST 850 MB SPEED CONVERGENCE.

THE HIRES MODELS DO NOT HAVE A STRONG HANDLE ON THIS CONCENTRATED
AREA OF CONVECTION...WITH THE ARW/NMMB/NSSL-WRF AND LATEST RUN OF
THE HRRR SHOWING POOR CONVECTIVE ORGANIZATION AND A VERY SCATTERED
NATURE TO THE ACTIVITY ALONG THE BOUNDARY THROUGH THE MID-MORNING
HOURS. THE NMMB DID DEPICT SOME LOCALLY INTENSE CORES OVER PARTS
OF SOUTHWEST MO...BUT THE CURRENT ACTIVITY IS EAST OF THE NMMB
PLACEMENT.

THERE IS ENOUGH SUPPORT IN SATELLITE IMAGERY WITH CLOUD TOPS STILL
COOLING SOMEWHAT...THAT CONVECTION WILL PERSIST FOR A FEW MORE
HOURS BEFORE THEN WEAKENING TOWARD 15Z. THIS WILL BE SUPPORTED BY
THE AFOREMENTIONED SHORTWAVE DYNAMICS AND SURFACE WAVE. EXPECT
RAINFALL RATES TO APPROACH 2 INCHES/HR....WITH STORM TOTALS ACROSS
THE THREAT AREA LOCALLY EXCEEDING 5 INCHES GIVEN THE VERY SLOW
CELL MOTION AND DEEP POOL OF MOISTURE ALREADY IN PLACE OVER THE
REGION AS CONFIRMED BY GPS-DERIVED PWATS OF 1.7 TO 1.8 INCHES.
FLASH FLOODING IS LIKELY TO CONTINUE BASED ON THE SET-UP. WILL
CONTINUE TO MONITOR.

ORRISON

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

ATTN...WFO...LZK...SGF...TSA...

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

LAT...LON   37489265 37179192 36379251 35969378 36229434
            36719410



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