Area Forecast Discussion
Issued by NWS Las Vegas, NV

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FXUS65 KVEF 191100
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
300 AM PST Fri Jan 19 2018

.SYNOPSIS...A Pacific storm system will bring strong winds and
precipitation to the area today and Saturday. Rain and mountain
snow will spread across much of the region Friday night into
Saturday, with the heaviest snow expected above 5000 feet in
Lincoln county. Snow showers with some light accumulations are
possible below 5000 feet in Nye, Lincoln, Clark and Mohave
counties as much cooler temperatures arrive with a cold front
Friday night and Saturday. Cool and dry conditions are expected on
Sunday with temperatures slowly moderating by early next week.
&&

.SHORT TERM...Today through Sunday night.

An approaching shortwave trough will lead to strong winds, mostly
cloudy skies, and a significant cool down over the next two days.
This system has started to pivot eastward this morning and will
continue on a progressive eastward track, passing over southern
Nevada on Saturday.

As the storm advances toward the region today, a belt of gusty
south to southwest winds will develop ahead of a cold front this
afternoon, with wind speeds between 15-25 and gusts 25-40 mph
possible. There may be some localized spots that meet wind
advisory criteria, but most of the region should stay below
thresholds. A cold front will sweep through the area this evening
and make it through the entire region by Saturday morning. Post-
frontal winds have trended up over the past few model runs, but
still look to be below advisory criteria. However, there will be
a brief period tonight where portions of Nye, Esmeralda Counties,
and the Owens Valley may reach advisory level winds in response
to a tightening surface gradient. Confidence on 40+ mph winds is
too low to warrant an advisory. Breezy post-frontal winds will
stick around through most of Saturday and taper off Sunday.

Chances of precipitation will increase today through Saturday,
mainly across Inyo, Esmeralda, central Nye, Lincoln, northeast
Clark and Mohave Counties. Models have trended slower with the
onset of precipitation, so chance PoPs were pushed back across
the northern zones by 6 hours. There will likely be two main bands
of precipitation with this system: (1) along and ahead of the
cold front and (2) precipitation wrapping around the backside of
the low. Precipitation is expected primarily tonight into Saturday
morning across the northern zones, with a few showers lingering
in Mohave County Saturday afternoon. High elevation snow
accumulations are still forecast to be the highest across Lincoln
County, with 3-8 inches above 5000` and localized amounts of 10-14
inches in higher elevations. A Winter Storm Waring is in effect
for tonight through Saturday morning for elevations above 5000` in
Lincoln County. Blowing snow will be likely with gusty post-
frontal winds. A few inches of new snow above 7000` will also be
possible in the Spring and Sheep mountains, though as mentioned
the heaviest precip will be focused to the north.

Temperatures will drop 5-8 degrees below normal Saturday after the
cold frontal passage. This will be the coldest of temperatures
2018 thus far. Overnight lows in Las Vegas will fall into the mid
to low 30s Saturday and Sunday night.

The system will exist to the east Saturday night and shortwave
ridging will quickly build in behind. Quiet, cool conditions are
expected Sunday.

.LONG TERM...Monday through Thursday. Two storm systems are expected
to affect the region during this period as progressive westerly flow
continues. First weak system will pass by Monday, with most precip
chances remaining north of our CWA. Flat ridging is expected
Tuesday, then the flow will start to buckle more southwesterly
Wednesday ahead of the next, stronger system for Wednesday night and
Thursday. At this time, it appears that precip chances will be
limited to the southern Great Basin, with gusty winds for the Mojave
Desert. Temperatures should be within a few degrees of late January
normals, with Thursday likely to be the warmest day due to
increasing winds and mixing ahead of the incoming storm system.
&&

.AVIATION...For McCarran...Gusty southwest winds will increase later
this morning between 16z-19z, with speeds between 10-15 kts
increasing to 15-20 kts in the afternoon. Peak gusts of 35 kts are
possible and are expected primarily during the afternoon/early
evening, but gustiness will continue through Saturday morning. A
front will shift wind to northwest Saturday morning between 13z-16z.
Confidence is low on the precise time of the wind shift. After the
shift, winds will likely remain gusty through Satudray evening.
CIGs should remain above 20 kft prior to the frontal passage, then
drop below 10 kft as the front passes.

For the rest of southern Nevada, northwest Arizona and southeast
California....Gusty south/southwest winds will develop this morning
ahead of a cold front that will sweep across the area tonight-
Saturday morning and shift winds to the north/northwest. Wind speeds
between 10-25 kts with gusts 25-35 kts are expected today. Slightly
stronger gusts are expected behind the front, with gusts up to 40
kts possible. Dry conditions are expected at all sites, except KBIH
where there is a chance of light rain this evening. CIGs generally
remain above  15 kft today with broken to scattered skies. With
potential shower activity tonight at KBIH, CIGs below 5 kft may be
possible.
&&

.SPOTTER INFORMATION STATEMENT...A storm system will bring gusty
winds and increase precipitation across the northern counties this
weekend. Spotters are encouraged to report any significant
weather or impacts according to standard operating procedures. &&

$$

SHORT TERM/AVIATION...Boothe
LONG TERM.............Morgan

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