Area Forecast Discussion
Issued by NWS Las Vegas, NV

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FXUS65 KVEF 250421 AAA

Area Forecast Discussion
National Weather Service Las Vegas NV
920 PM PDT SAT SEP 24 2016

.SYNOPSIS...Mostly clear skies and a warming trend can be expected
through Monday. Northerly winds will be strong and gusty at
times...especially down the Colorado River Valley on Sunday. An
upper level low moving up from the south will provide a slight
chance of showers across northwest Arizona and southern Nevada on
Tuesday and Wednesday.

.UPDATE...North-South surface pressure gradient is
tightening across the area tonight. Latest gradient between Ely and
Needles running around 12 mb. The increasing gradient is developing
between a strong ridge building in across California/northern Great
Basin and a low developing over Arizona/northwest Mexico. Strongest
winds Sunday will be down the Colorado River Valley between Lake
Mohave and Needles. Based on latest guidance will be issuing a Wind
Advisory for that stretch of the river. Looks breezy at times
elsewhere. No other changes expect the addition of the advisory.

.AVIATION...For McCarran...Possible northeast winds up to 10kts
after 06z this evening shifting more northwest between 10z and 12z
Sunday morning. Stronger/gustier northeast winds begin to develop
after 16z Sunday with gusts up to 25kts possible through late
afternoon before starting to subside in the early evening.
Mostly clear skies through the period.

For the rest of southern Nevada...northwest Arizona...and southeast
California...North to northeast winds will start to increase down
the Colorado River Valley tonight, peaking Sunday morning through
the afternoon hours before starting to relax in the early evening.
Wind gusts between 35-40kts possible at KIFP and KEED. Elsewhere
strongest north to northeast winds will occur Sunday morning through
late afternoon with gusts of 20-30kts at times. Mostly clear skies
through the period.

.Discussion...Tonight through Saturday.

A strong upper ridge of high pressure will build into California and
then northern Nevada tonight through Monday. Meanwhile, a closed
upper low will develop across northwest Mexico and Baja. This
pattern will lead to dry conditions along with locally breezy north
to northeast winds. The strongest winds are expected down the
Colorado River Valley on Sunday where gusts to 30 mph will be common
at times between Laughlin/Bullhead City and Needles. Gusts around 35
mph are possible but mainly isolated to the Laughlin/Bullhead City
area. At this time I expect winds on Lakes Mead, Mohave and Havasu
to remain below Lake Wind Advisory levels but boaters should plan
for rough water. By Tuesday, the closed upper low will start to head
north, bringing moisture up into the area. At this point it looks
like showers/thunderstorms will be possible over much of Mohave and
Clark Counties and far eastern San Bernardino County by Tuesday
afternoon. Precipitation chances continue will spread north across
southern Nevada Tuesday night and Wednesday as the low weakens and
moves into southern Nevada and southwest Utah. A Pacific trough
approaching the coast Thursday will start to push the weakening low
and associated moisture east of the area but there may be just
enough residual moisture and instability for a slight chance of
thunderstorms over eastern Lincoln and northern Mohave Counties. The
Pacific trough is forecast to creep slowly east Friday and Saturday
with a likely increase in southwest winds over the forecast area.
While some models develop precipitation over the eastern part of the
forecast area, the layer RH progs show pretty dry air and
instability looks weak to non-existent, so I kept precipitation out
of the forecast. Overall, temperatures through the period look to be
close to normal.

.SPOTTER INFORMATION STATEMENT...No significant weather is expected
today. Gusty north winds are expected down the Colorado River Valley
on Sunday. Spotters are encouraged to report according to standard
operating procedures.




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