000
FXUS65 KREV 212234
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
234 PM PST Wed Feb 21 2018

.SYNOPSIS...

Below average temperatures will dominate through at least next
week as low pressure remains over the West. A series of systems
will bring the threat for snow, with the first on Thursday
bringing a widespread light to moderate snowfall. Most areas will
see a break Friday through the weekend, with another system
expected Monday into Tuesday of next week.

&&

.SHORT TERM...

SUMMARY OF IMPACTS THROUGH THURSDAY NIGHT:

* Burst of snow (periods with snowfall rates up to 2 inches/hour
  possible) for the western Nevada morning commute Thursday.
  RAPIDLY DETERIORATING CONDITIONS EXPECTED.

* Local snowfall amounts to 6 inches in lake-effect snow bands
  south and southeast of Lake Tahoe and Pyramid Lake, including
  Douglas and El Dorado Counties and between the Tahoe-Reno
  Industrial Center and Fernley.

* Possible evening commute issues due to flash freezing of wet
  afternoon-evening roads.

* Wind chills to -20F in the high Sierra Thursday.


Simulations continue to bring a strong front through northeast
California and western Nevada tomorrow morning, affecting
Susanville to Gerlach before sunrise and the I-80 and Highway 50
corridors around rush hour. Areas in Mono and Mineral Counties
should expect to see snow developing by around mid-morning
Thursday.

With remarkable forcing, deep moisture, and slightly unstable
conditions (very cold system), a burst of moderate to briefly
heavy snowfall can be expected within an hour or two on either
side of the frontal passage...especially north of Walker Lake to
Coleville line and along/east of Highway 395. The burst of snow is
expected to bring rapidly deteriorating commute conditions and,
with the much higher volume of travel, possible major headaches
and lengthy commute times. While snow may be developing by around
5 AM in the Reno-Sparks area, if you can get out ahead of the
main commute time you could reduce your chance of a terrible
commute to work (less volume of traffic).

Farther south including Hawthorne and Bridgeport, more uncertainty
comes into play impact-wise as some simulations weaken the
frontal forcing with less chance for moderate to heavy snow. In
addition, the front is arriving into the daylight hours so if snow
winds up lighter roads may stay just briefly slushy or wet.

After a possible break in snow an hour or two after the cold
frontal passage, scattered to numerous snow showers are expected
to re-develop for the afternoon and early evening as the core of
the inside slider/upper low moves overhead. In addition, simulated
soundings support the possibility for lake effect snow bands to
the south and southeast of Lake Tahoe and Pyramid Lake, with
medium confidence for another several inches of snowfall in
portions of Douglas and El Dorado Counties, as well as between
the Tahoe-Reno Industrial Center and Fernley (including I-80).
Elsewhere, snow showers are more likely to remain light Thursday
afternoon and evening. With the late February sun heating roads to
well above the air temperature, snow showers will need to be
persistent and at least moderate in intensity to cause road issues
after about 9-10 AM Thursday. Therefore, impacts to travel could
diminish rapidly by late Thursday morning outside of lake effect
snow areas.

Precipitation tapers off on Friday. Another wave is expected to
move over northern and eastern Nevada on Saturday. This could
bring a few light snow showers south to about Highway 50 by
Saturday night; however, the main forcing for snow showers is well
east of the region so snowfall amounts should remain minimal,
especially from I-80 south. -Snyder

.LONG TERM...Sunday through Wednesday...

Unsettled weather continues next week as a series of shortwave
troughs descend from the Gulf of Alaska and across the western U.S.
The first trough looks to impact the northern Sierra and western
Nevada in the Monday-Tuesday timeframe and would provide another
reinforcing shot of cold air and snowfall along a fast moving cold
front.

The latest trends and largest ensemble spreads have shown a more
offshore trajectory with this low. This may yield some higher
moisture content with the storm but it is still maintaining enough
cold air to drop snow levels to all valley floors. Confidence in the
low`s trajectory and timing is still low to moderate at this time,
but that is typical with these types of waves and confidence should
increase heading into the weekend. At this point, travel across
the Sierra and western Nevada looks good through Sunday but the
chances for winter driving conditions from accumulating snowfall
are increasing starting early Monday morning. Additional systems
providing reinforcing shots of cold air and snowfall by midweek
into next weekend are possible. Fuentes

&&

.AVIATION...

The next storm system/cold front moves into the region tonight
into Thursday morning, bringing widespread light to moderate snow
to the region, including the lower elevations in northeast CA and
western Nevada. Breezy winds along the front, along with moderate
snow will bring periods of MVFR/IFR CIG/VIS and widespread terrain
obscuration to area terminals, especially north of KO57 (Bridgeport)
and KHTH.

After a break for a few hours after the frontal passage,
additional snow showers will develop in the afternoon and evening
Thursday, although pinpointing where the heavier snow showers and
major reductions to CIGS/VIS will be is of low confidence. The
only exception will be south and southeast of Pyramid Lake and
Lake Tahoe where lake effect snow bands could develop.

Storm total snow amounts for KTRK-KTVL will be around 3-6 inches,
with about 1-3 inches expected for KRNO-KCXP, and up to 2-3 inches
for KMMH. Snow accumulations are also likely for KNFL-KLOL with
up to 1-2 inches possible. -Snyder/Hoon

&&

.REV Watches/Warnings/Advisories...
NV...Winter Weather Advisory from 12 AM Thursday to 7 PM PST
     Thursday NVZ005.

     Winter Weather Advisory from 7 AM Thursday to 4 AM PST Friday
     NVZ001.

     Winter Weather Advisory from 4 AM to 10 PM PST Thursday NVZ002.

     Winter Weather Advisory from 4 AM to 10 PM PST Thursday
     NVZ003-004.

CA...Winter Weather Advisory from 12 AM Thursday to 7 PM PST
     Thursday CAZ070-071.

     Winter Weather Advisory from 7 AM Thursday to 4 AM PST Friday
     CAZ073.

     Winter Weather Advisory from 4 AM to 10 PM PST Thursday CAZ072.

&&

$$

For more information from the National Weather Service visit...
http://weather.gov/reno

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