Area Forecast Discussion
Issued by NWS Las Vegas, NV

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FXUS65 KVEF 211145

Area Forecast Discussion
National Weather Service Las Vegas NV
344 AM PST Tue Feb 21 2017

.SYNOPSIS...A storm system over central and northern California will
bring high elevation snow to the southern Sierra Nevada and White
Mountains through Tuesday morning. This system will bring strong
winds to the southern Great Basin zones Tuesday followed by
scattered showers and cooler temperatures Wednesday. This will lead
to a weather pattern change with cool and unsettled weather through
the weekend.

.SHORT TERM...through Thursday night.

Early morning satellite shows broad upper trough over the eastern
Pacific. Several disturbances embedded within the trough with
freckled cloudiness highlighting pockets of cold air aloft. Along
southern edge of upper trough plume of warm...moist air continues to
stream in across central California/Tahoe Basin. Models agree
orographic lift on the west side of the southern Sierra Nevada will
weaken throughout the day with snow accumulations along the eastern
Sierra Slopes lessening. Will allow the Winter Weather Advisory to
run its course through 10 am this morning. Automated sensors from
Rock Creek Lakes south to South Lake and Big Pine Creek showed
between 10 and 14 inches of new snow between 3 am and 6 pm Monday.

The trough is progged to move inland across the Great Basin Wednesday
and Thursday. Still some differences between models regarding how
much precip will break out in the southern Great Basin. Still looks
like the best chance on Wednesday will be near/along the cold front
draped across central Nye and northern Lincoln Counties. Precip
along the frontal band looks to weaken as it moves through Clark
County Wednesday evening but can not rule out a few showers in the
mountains and possibly northeast Clark County. On Thursday a slight
chance of showers remains in the forecast for northern Lincoln

Windy the next two days with a Wind Advisory for much of southern
Nevada today. Did extend the timing for the Spring Mountain/Red Rock
Canyon as it looks like winds will last through the night. Probably
need another Wind Advisory for parts of San Bernardino County
Wednesday/Wednesday night. Will allow day shift one more chance to
evaluate the timing and areal coverage.

Temperatures will be around 12 degrees cooler on Thursday than

.LONG TERM...Friday through Monday.

Another wet period appears to be taking shape in the longer term as
models are now suggesting that troughing will develop further west
off the pacific coast and move inland over the weekend. This deep
troughing offshore will allow for two separate weather features to
merge over the open ocean, providing a deeper pacific moisture tap
into the California coastline which will then penetrate inland as
the trough moves ashore.   Expect increasing clouds on Saturday with
rain and snow breaking out across the Sierra and Owens Valley, with
rain and mountain snow chances spreading across the entire region
Sunday or Sunday night.  The trough then looks to linger across the
west through midweek. This will result in a cool and showery weather
pattern for much of the region through early next week.

While the details are still coming together, the potential is there
for another round of significant precipitation in the Owens Valley.
Generally lighter rain looks like a good bet elsewhere, but soggy
conditions could still impact weekend plans pretty much anywhere in
the region.  We will continue to monitor this period in upcoming
shifts and gradually ramp up the precipitation chances if it
continues to evolve as it appears now.

.AVIATION...For McCarran...South to southeast winds occasionally
gusting 15-20 kts into mid-morning. Gusty south winds are expected
to develop by this afternoon with gusts 20-30 kts at times. A few
clouds will be around 6 kft agl but overall CIGS will be above 15
kft. Areas of mechanical turbulence should be expected near the
mountains through Tuesday night.

For the rest of southern Nevada...northwest Arizona...and southeast
California...Can not rule out a light shower in the vcnty of KBIH
this morning along with lower CIGS. CIGS looks to improve by late
afternoon. Gusty south-southwest winds over 35 kts will be fairly
widespread across the southern Sierra and southern Great Basin this
afternoon. Parts of San Bernardino County will see west-northwest
wind gusts over 35 kts Wednesday afternoon and night.

.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating


Short Term/Aviation...Pierce
Long Term...Outler

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