Area Forecast Discussion
Issued by NWS Las Vegas, NV

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FXUS65 KVEF 191846 AAA
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
353 AM PST Thu Jan 19 2017

.SYNOPSIS...Widespread rain and mountain snow will spread across
the region today. A brief break is expected overnight before a
second system moves in Friday into Saturday. Yet another wet system
will move through Sunday and Monday.
&&

.UPDATE...Areas of light to occasional moderate rain slated to
continue moving east through southern Nevada/eastern California into
early evening/Mohave County late evening before tapering off ahead
of our second system which models indicate will produce even more
rain and mountain snow. Satellite show more breaks in clouds in our
far western zones so did cut back on cloud cover and POPs the rest
of today. Have not seen any lightning yet but models do indicate a
slight chance so kept the mention in the forecast.
&&

.PREV DISCUSSION...353 AM PST THU JAN 19 2017
.SHORT TERM...Today through Saturday.

The first band of precipitation that moved through last evening
produced little QPF across the region, however a second band is
currently moving across Inyo and San Bernardino counties this
morning. Rain has changed over to snow near Bishop, CA, where some
light accumulation is possible through this morning. This second
band is expected to produce a bit more QPF than the first, resulting
in the beginning of significant valley rain and mountain snow for
areas east of the Sierra (where 7-10 inches of snow have already
fallen at several SNOTEL sites). A few areas will see some gusty
winds of 20-35 mph late this afternoon and evening as this storm
exits to the east.

A break is expected this evening and overnight before a second storm
system moves into the region Friday. Guidance continues to indicate
that this storm will produce more QPF than the first, with snow
levels between 4000-5000 feet. Therefore all winter weather
highlights remain in place. I did update the highlights to reflect
combined snowfall totals for both systems. Please see those products
for additional details (RNOWSWVEF). Winds are expected to be
somewhat stronger with this system as well, gusting 35-45 mph
across portions of the Mojave Desert. A wind advisory may be needed
for Friday, mainly for the western half of San Bernardino County.

Precipitation with the second band is expected to diminish Friday
night through Saturday morning.

.LONG TERM...Saturday Night through Wednesday.

One final wave will bring another round of widespread rain and
mountain snow to the region Sunday and Sunday night, with showers
lingering into Monday.  There remains uncertainty in the amount of
precipitation expected with this system, but it has the potential to
be as wet if not wetter than the storm system that precedes it
Friday/Friday night. In addition, large and robust nature of the
trough will make for powerful dynamics to force locally heavy
precipitation and bring down snow levels below some local passes.
Mountain Springs on US-157 and Mountain Pass on the I-15 will need
to be watched closely both Sunday morning and early Monday morning
for potential travel impacts. In addition, another 6-12 inches of
snow can be expected in the above 5500 feet in the Spring Mountains.
Higher elevations east of Kingman may be impacted as well.   Aside
from increasing PoPs and tweaking QPF, overall I made few major
changes to the extended period.

After Monday, a large ridge will attempt to build into the West
Coast with a dry northwest flow taking over our region. Temperatures
will remain cool, with north breezes especially down the Colorado
River, but otherwise will be generally dry.
&&

.AVIATION...For McCarran...Light rain showers possible into early
evening with CIGs possibly lowering 4-5k feet. There will be a
slight chance of embedded thunderstorms in the showers. CIG and
precipitation conditions will begin to improve later this afternoon,
however southwest winds gusting 15-20kts are possible. Winds should
relax some this evening and may briefly take on a west to northwest
direction before settling back to the southwest. Another round of
rain and low CIGs is expected to arrive by mid-day Friday.

For the rest of southern Nevada...northwest Arizona...and southeast
California...Widespread rain and mountain snow showers are expected
across eastern California, northwest Arizona and southern Nevada.
This will also bring low CIGs and VSBYs to the region, generally in
the 4-5kft range and VSBYs 3-5 miles. This first weather system is
expected to move east of the area by this evening. However another
round is expected Friday and Friday night. A few areas will see wind
gusts 15-25kts with both waves.
&&

.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
rain and snow amounts as well as any weather-related impacts or
damage.
&&

$$

Update...Pierce

Short Term/Aviation...Wolcott
Long Term.............Outler

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