Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 172307
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
307 PM PST Thu Jan 17 2019

.SYNOPSIS...

Winter storm continues to bring snow, rain and gusty winds through
this evening, which could bring a messy evening commute along the
Highway 395 corridor while Sierra roads will be impassible at
times. Drier conditions return Friday, but a warm front may bring
light snow mainly north of I-80. After a dry and mild Saturday, a
fast moving storm system brings one more round of rain, snow and
gusty winds for Sunday. Dry weather is then expected next week.

&&

.SHORT TERM...

No major changes to the forecast. We did increase QPF and snow
amounts for the Sierra and western Nevada though the rest of this
afternoon and evening. A major winter storm continues to affect
the Sierra through this evening with heavy snow and gusty winds.

We are under an unstable air mass as the trough moves over our
area, causing convective snow showers to push over the Sierra and
into northeast California and western Nevada. Heavy snow continues
to fall in the Sierra around Tahoe and Mammoth, with additional
accumulations through this evening. Snow yesterday and last night
had a very heavy abundant water content. This snow was actually
very beneficial to the snowpack. We are now seeing snow pack
numbers in the Sierra around 110-120% of normal. Additional snow
amounts through this evening will help to increase those as well,
with up to 6-12 inches additional snow possible above 7000 feet
along the Sierra Crest. The Winter Storm Warnings for the Sierra
remain in effect through 4 AM Friday.

Snow levels have been hovering around 5000 ft today, although
snow has had trouble sticking below 6000 ft. That being said, we
will see snow begin to stick in the lower elevations this evening
as the sun goes down. Additional snowfall amounts of up to a
couple inches are possible above 5000 ft around the Reno-Carson
areas, with a light dusting (generally less than one inch)
possible down to the valley floors. Be prepared for potentially
deteriorating and slick conditions during the evening commute. The
Winter Weather Advisory for the Reno-Carson-Minden area remains in
effect through 7 PM this evening.

Gusty winds continue this evening over Mineral County with gusts
up to 50 mph. Wind advisory remains in effect there until 7 PM,
then diminishing overnight. The winter storm in the Sierra begins
to diminish tonight, but by Friday a warm front will move into
northern CA and far northwestern NV. A couple inches of additional
snowfall may be possible Friday evening in the northern Sierra,
northeastern CA, and into far northwestern Nevada. Friday night,
snow levels will raise up to near 6500-7000 ft as the warm front
moves over the area. -Hoon

.LONG TERM...Sunday through next week...

Changes: Another round of increasing pops, winds, and QPF for
Sunday`s system.

A fast-moving wave is projected to move southeastward from off the
Oregon coast through the region Sunday. This wave is appearing more
dynamic than previous runs were showing, with stronger forcing
evident along and ahead of the frontal boundary. Subsequently,
moisture and precipitation chances were increased further.

Currently, the expected evolution of the system is that it will
move into the Sierra early Sunday with precipitation spreading
over western Nevada during the day. While western Nevada initially
appears somewhat shadowed, there will be an appreciable period of
spillover as the boundary approaches in the afternoon. Snow
levels and timing of the wave support mostly rain for western
Nevada valleys, with snow levels dropping to around 5000 feet as
the wave passes. Forcing parameters could allow for a brief period
of snow to reach valley floors along the boundary itself.
Preliminary snow totals are generally around 1 foot of snow above
7000 feet along the Sierra crest, a few inches possible after a
rain/snow transition around Lake Tahoe, and an inch or so down to
5000 feet. Not an impressive amount, but enough to likely cause
some travel impacts over Sierra passes.

Winds will be gusty, generally around 40 mph, along the Sierra Front
ahead of the boundary through Sunday afternoon. Ridge top gusts
around 100 mph will cause some mountain wave activity and
turbulence over and around the Sierra.

Otherwise, general troughiness will remain along the Nevada interior
with potential for weak slider-like systems moving through the
remainder of the week, bringing breezy winds and minimal amounts
of precipitation. There are no big signals at this time in terms
of moisture after the Sunday system for the next week. Boyd

&&

.AVIATION...

Snow will continue for Sierra terminals through this evening with
periods of heavy snow expected to bring significant accumulating
snow to KTRK/KTVL/KMMH. Sierra sites will likely remain below
minimums through this evening before snow begins to taper to showers
overnight and conditions improve late tonight and early Friday.
Latest model simulations indicate some light snow possible Friday
afternoon and evening for the Tahoe basin northward with lowering
CIGS/VSBYS and light accumulating snow.

For lower elevations, gusty winds will bring periods of moderate
turbulence and LLWS this afternoon as ridge level winds continue to
gust over 100 kts and south-southwest surface winds increase to 20-
25 kts with gusts 30-40 kts. The next wave is moving into the Sierra
at this time and will continue to bring a more steady rain (snow
mainly above 5000 feet) this afternoon especially for KRNO and
KCXP. CIGS have lowered enough to obscure higher terrain and rain
could briefly change over to snow before tapering this evening.
Accumulation should generally be 1/2 inch or less and mainly on
unpaved surfaces.

Another storm will roll in on Sunday, not as potent as this one, but
still capable of producing some moderate snow accumulations at
Sierra terminals and turbulence for all areas. Hohmann/Boyd

&&

.REV Watches/Warnings/Advisories...
NV...Winter Storm Warning until 4 AM PST Friday NVZ002.

     Wind Advisory until 7 PM PST this evening NVZ001.

     Winter Weather Advisory until 7 PM PST this evening NVZ003.

CA...Winter Storm Warning until 4 AM PST Friday CAZ071.

     Winter Storm Warning until 4 AM PST Friday CAZ073.

     Winter Storm Warning until 4 AM PST Friday CAZ072.

&&

$$

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


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