Winter Storm Watch 3, NWS Reno, NV

Area Forecast Discussion
National Weather Service Reno NV
213 AM PST Tue Feb 27 2018

.SYNOPSIS...

The active weather pattern will persist this week with below
average temperatures and chances for snow. A strong winter storm
with gusty winds and snow will impact travel in the Sierra and
western Nevada Thursday through Saturday. Significant snow is
almost a guarantee for the Sierra while snowfall in lower
elevations could be heavy at times as well.

&&

.DISCUSSION...
Most of the snow showers have ended as of early this morning, but
plan on taking it slow and leaving plenty of time for the morning
commute. Roads will likely be icy and slick for both the Sierra
and western Nevada this morning. Snow showers will continue for
portions of Mono county, mainly from Bridgeport southward with
additional light accumulations possible. Breezy east winds may
produce choppy conditions on Lake Tahoe through mid morning, so
take caution and wait for conditions to improve before venturing
out onto lake waters. Otherwise, a light northeast flow will keep
temperatures chilly today with drier conditions for all areas
north of Highway 50.

Wednesday will be the last relatively quiet day before the next
storm blasts into the region. Cloud cover will be increasing through
the day and breezy conditions will develop by the afternoon ahead of
the next storm. For the most part, Wednesday will be a great day to
prepare for the next storm.

Bottom line: The next system is a major winter storm that will bring
gusty winds, heavy snow to the Sierra, and even accumulating snow
to the valleys of northeast California and western Nevada. We
strongly advise that people prepare for hazardous winter weather
conditions, highway closures, and very long travel delays. This
storm is the most impressive that we have seen this season.

If you have been patiently waiting to read about snow totals in feet
instead of inches, then this storm will be your best chance for that
this season. The major winter storm will move into the region late
Wednesday night and stick around through Saturday. Forecaster
confidence is high for major impacts in the Sierra (and likely in
western NV as well) due to this winter storm.

Simulations have been in impeccable agreement over the past 5 days
with dropping a deep and cold low pressure system just off the Pac
NW coast. The position of the low is a known favorable position for
heavy snow in the Sierra and western Nevada. Cold polar air will be
paired with the dynamics of the low and substantial Pacific moisture
that will be directed into the Sierra with a very strong Pacific
jet. This setup would be a significant snowpack producer for the
Sierra, and would lessen the snow drought but not completely
eliminate it.

WINDS: Strong gusty winds will develop along the US-395 and I-580
corridor on Thursday ahead of and along the cold front with wind
gusts between 50-60 mph possible. Sierra winds will be typical of
a strong winter storm with gusts approaching 100 mph on the
Sierra ridges. Once the cold front pushes through Thursday
afternoon, winds should dampen for lower valleys and foothills but
winds will continue in the Sierra and likely produce localized
blowing snow and limited visibility throughout the storm.

PRECIPITATION: As the cold front pushes down on Thursday, we will
start to see precipitation spillover into the valleys of
northeastern CA and western NV. Although snow levels will
temporarily bump up to near 4500 feet (rain/snow mix for valleys),
the snow levels will plummet to all valley floors Thursday night
behind the front. The initial wave on Thursday appears to be the
heaviest period of snow for the Sierra, although this storm will
continue through Friday and Saturday as additional shortwaves rotate
through the trough. Plan on multiple rounds of moderate to heavy
snow in the Sierra and northeast CA, and even for northern Nevada.
Late Thursday night into Friday will be the critical day for western
Nevada with snow levels down at all valley floors. Model guidance
shows impressive amounts of snow for the Sierra as well as the Reno-
Sparks-Carson City areas for Friday with widespread travel impacts
expected.

STORM TOTALS: Snow amounts for Thursday-Friday-Saturday will be
around 3 to 5 feet in the High Sierra above 7000 feet, with a couple
feet of snow around the 6000 ft elevation, including Lake Tahoe.
Several inches of snow are expected for the valleys of western
Nevada with localized higher amounts up to a foot for elevations
above 5000 feet in the foothills. -Edan

&&

.AVIATION...

An upper low along the central CA coast will continue to drop
south and away from the area today. Light snow and low clouds will
continue to bank along the eastern Sierra from Alpine to Mono
County this morning with terrain obscuration and light
accumulating snow for the KMMH terminal. Low clouds and flurries
may continue as far north as Highway 50 as well through midday.
As the low moves south, snow should diminish from north to south
with low clouds gradually lifting and breaking up later in the
afternoon and early evening. Otherwise a general northeast flow
will prevail today with winds gradually diminishing along the
Sierra crest.

A very strong storm is forecast for Thursday-Saturday, bringing
periods of hazardous winds and turbulence, along with significant
snowfall. Hohmann

&&

.REV Watches/Warnings/Advisories...
NV...Winter Storm Watch from late Wednesday night through Saturday
     morning NVZ002.

     Winter Storm Watch from Thursday afternoon through Saturday
     morning NVZ003-005.

CA...Winter Storm Watch from late Wednesday night through Saturday
     morning CAZ071>073.

     Winter Storm Watch from Thursday afternoon through Saturday
     morning CAZ070.

     Winter Weather Advisory until 7 AM PST this morning CAZ073.

&&

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