High Wind in California, January 13 to 14, 2020

Area Forecast Discussion
National Weather Service Reno NV
306 PM PST Mon Jan 13 2020

.SYNOPSIS...
Active week continues with a series of weak to moderate winter
storms. Snow and wind impacts will be accompanying each of these
storms starting tonight. Light to moderate snow is expected for
the Sierra and northeast California, while strong winds impact
much of western Nevada. The strongest of the storms moves in
Wednesday night through Thursday with heavy mountain snow and more
strong winds. A drier period is setting up for next week.

&&

.SHORT TERM...

No big changes to the forecast today. Primary concerns remain the
same this afternoon, including strong winds and some snow.

The next storm pushes in tonight brining snow to the Sierra and
northeastern CA and strong winds to much of the region. Let's take a
look at some of the details. As of 2pm, Cedar and Fredonyer Passes
on northeastern California were already snow-covered and several
wind sites are reporting gusts between 45-55 mph this afternoon.
This is just the beginning of this storm.

WINDS: Hang onto your hats and steering wheels as strong winds will
produce dangerous crosswinds, severe turbulence, and areas of
blowing snow for mountain areas. High wind warnings are in place for
much of the Highway 395-Interstate 580 corridor, with wind gusts 50-
65 mph forecast. Wind prone locations may experience wind gusts up
to 80 mph during this wind event. Lift operations may also be
impacted during this storm, so check the conditions before you head
out.

  *Plan for travel impacts, including aviation turbulence and
restrictions for high profile vehicles.
  *Secure outdoor items, and monitor fences and gates so that
critters/pets don't escape.

Winds will drop off noticeably late Tuesday into Wednesday morning
before ramping up again ahead of the next stronger storm. See the
long term discussion for those details.

SNOW: Roads in the Sierra will be slick with accumulations generally
2 to 5 inches for Sierra valleys and 6 to 10 inches in the higher
Sierra and over passes. South of Highway 50 snow is forecast to be
much less, as the system weakens as it moves through the region.
Travel may be difficult with winds whipping snow and lowering
visibility to less than half a mile. For lower western NV valleys,
the snow potential will also be pretty low. Don't be surprised if
you experience some snow flurries, but accumulations will likely be
zero or a dusting. -Edan

.Long Term...Wednesday and Beyond.

The main event snow storm is still forecast for Wednesday night into
Thursday. Changes were made today to slow the start of the event and
raise snow levels in the lee of the Sierra. Reno remains in the
boom/bust zone due to a large range of snow level and spillover
precipitation scenarios.

Wednesday still looks like a good travel day over the Sierra with
a solid break between precipitation events. Model simulations
have continued to slow the onset of precipitation into the Sierra
with estimates of onset along 8-12 pm Wednesday night for Donner
Summit and the northern Sierra, and about 6 hours later in Mono
County.

The upper-level low pressure is also showing signs of splitting
as the system approaches as the system to occludes offshore. The
other aspect of the storm is that it does move through the region
rapidly which will limit the overall snow totals. That being said
1-2' along the Sierra crest still looks like a good bet. Snowfall
in western Nevada, as per usual, is a much bigger challenge.

How much spillover precipitation will make it over the Sierra and
what will snow levels be? As the system begins to show signs of
splitting and strong southerly flow near the surface ahead of the
cold front points towards less spillover and higher snow levels.
Nevada is also on the warm side of the jet until the front comes
through during the day Thursday. Continued to nudge down the QPF
amounts for western Nevada, and raised the snow levels somewhat
dramatically. The reasoning for snow level changes is: 1) Models
often over estimate the speed at of cold air moving across the
Sierra. 2) Models tend to over estimate the wet-bulbing effect.
Virginia City and the foot hills could still see a decent
accumulation, but we'll have to see how the next round of guidance
comes in and whether the splitting trend continues.

Winds along the crest could again be quite strong as 700 mb winds
increase to 50-60kts early Thursday morning. Surface winds aren't
expected to be as strong as the Monday night event, but occasional
strong gusty winds and substantial wind shear near the surface
could still be significant aviation hazard.

The best chances to see snow in Reno looks to be at the beginning
of the event overnight Wednesday when wet-bulbing effect should
be the strongest before warm southerly flow takes hold. Another
window for snow in Reno would be behind the front late Thursday,
when colder air would likely be in place and convective snow
showers are possible, but they would be sporadic.

Friday looks like another good travel day with another break in
precipitation expected as the storm track moves north, though some
convective snow showers can't be completely ruled out. A very
weak system could moves through over the weekend with some light
snow showers around the central Sierra on Saturday night. After
that, it looks like we'll see a break in the precipitation for at
least the first part of next week. -Zach

&&

.AVIATION...
Gusty winds will become strong overnight into Thursday morning as
model simulations indicate downslope winds surfacing across western
Nevada, downwind of the Sierra. Aviators and airport operations
should plan for very strong cross winds, severe turbulence and low
level wind shear over the next 18-24 hours. KRNO in particular has
been in a weak rotor for much of the day with directions varying
from calm to NE/E, but finally switched S/SW winds around 21z.

As this storm pushes through there will be chances for snow with a
dusting possible for western Nevada terminals and 2-4" of
accumulation possible in the northern Sierra and northeast
California, including KTRK/KTVL. Lesser totals up to 1" are possible
for KMMH.

Wednesday will be a brief reprieve before the strongest storm in the
series moves in Wednesday night into Thursday bringing heavy snow
and another round of strong winds, turbulence and wind shear. Check
out the long term section for additional details and forecaster
confidence. -Dawn/Edan

&&

.REV Watches/Warnings/Advisories...
NV...Winter Weather Advisory from 4 PM this afternoon to 4 AM PST
     Tuesday NVZ005.

     Lake Wind Advisory until 7 PM PST this evening for Lake Tahoe in
     NVZ002.

     Lake Wind Advisory from 10 AM to 7 PM PST Tuesday for Lake Tahoe
     in NVZ002.

     Winter Weather Advisory from 7 PM this evening to 10 AM PST
     Tuesday NVZ002.

     Winter Storm Watch from late Wednesday night through Thursday
     evening NVZ002.

     High Wind Warning from 10 PM this evening to 10 AM PST Tuesday
     NVZ003.

     Lake Wind Advisory from 4 PM this afternoon to 4 PM PST Tuesday
     for Pyramid Lake in NVZ004.

CA...Winter Weather Advisory from 4 PM this afternoon to 4 AM PST
     Tuesday CAZ070-071.

     Winter Storm Watch from Wednesday evening through Thursday
     afternoon CAZ071.

     High Wind Warning from 10 PM this evening to 1 PM PST Tuesday
     CAZ073.

     Winter Storm Watch from late Wednesday night through late
     Thursday night CAZ073.

     Lake Wind Advisory until 7 PM PST this evening for Lake Tahoe in
     CAZ072.

     Lake Wind Advisory from 10 AM to 7 PM PST Tuesday for Lake Tahoe
     in CAZ072.

     Winter Weather Advisory from 7 PM this evening to 10 AM PST
     Tuesday CAZ072.

     Winter Storm Watch from late Wednesday night through Thursday
     evening CAZ072.

&&

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