Flash Flood Guidance
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000
AWUS01 KWNH 200412
FFGMPD
KSZ000-NEZ000-201011-

MESOSCALE PRECIPITATION DISCUSSION 0707
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1211 AM EDT SUN AUG 20 2017

AREAS AFFECTED...CENTRAL AND EASTERN NEBRASKA

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

VALID 200411Z - 201011Z

SUMMARY...TRAINING/BACK-BUILDING CONVECTION IS EXPECTED TO
CONTINUE FOR AT LEAST A FEW MORE HOURS...PRODUCING ADDITIONAL
HEAVY RAINFALL AMOUNTS.  FLASH FLOODING IS POSSIBLE.

DISCUSSION...A LOW LEVEL JET INCREASING TO 30-40 KTS CONTINUES TO
SUPPORT A DEEPENING MOISTURE POOL ALONG AND NORTH OF A
QUASI-STATIONARY BOUNDARY EXTENDING FROM SOUTHEASTERN INTO CENTRAL
NEBRASKA.  LATEST SPC MESO ANALYSIS SHOWS PWS OF 1.3-1.5 ACROSS
MUCH OF THE HIGHLIGHTED AREA...WITH THE 02 UTC RAP SHOWING A
FURTHER INCREASE OVER THE NEXT FEW HOURS.  WITH THE LOSS OF
DAYTIME HEATING...CONVECTIVE INHIBITION HAS INCREASED ACROSS THE
REGION...HOWEVER MUCAPE VALUES REMAIN 2000-3000 J/KG ACROSS MUCH
OF CENTRAL NEBRASKA.  WEAK MID LEVEL ENERGY AND FAVORABLE UPPER
JET FORCING ARE EXPECTED TO CONTRIBUTE TO THE LARGER SCALE LIFT
ACROSS THE REGION...SUPPORTING ADDITIONAL STORM DEVELOPMENT OVER
THE NEXT FEW HOURS.  AS THE EVENING PROGRESSES...VEERING LOW LEVEL
WINDS SHOULD SUPPORT FORWARD PROPAGATION OF STORMS DURING THE
EARLY MORNING HOURS...HOWEVER ADDITIONAL TRAINING IS POSSIBLE AS
THE MEAN FLOW BEGINS TO PARALLEL THE SURFACE BOUNDARY.

THE HI-RES GUIDANCE HAS NOT PERFORMED OVERLY WELL ACROSS THIS
AREA...WITH EVEN RECENT RUNS OF THE HRRR NOT APPEARING TO HAVE A
VERY GOOD HANDLE ON THE CURRENT CONDITIONS.  THE EXPERIMENTAL HRRR
SEEMS TO HAVE A LITTLE BETTER HANDLE AND IS SHOWING LOCAL AMOUNTS
OF 2-3 INCHES FOR THE 6-HR PERIOD ENDING AT 10 UTC.

PEREIRA

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

ATTN...WFO...GID...LBF...OAX...TOP...

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

LAT...LON   42099952 42039745 41419598 39979586 40129685
            40369873 40979958 41509986


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