Lake Wind Advisory 63, NWS Reno, NV

Area Forecast Discussion
National Weather Service Reno NV
351 AM PST Fri Nov 25 2016

.SYNOPSIS...
Dry weather continues through Saturday morning with seasonable
temperatures. The next system will impact the region this weekend
with gusty winds Friday afternoon and Saturday for eastern CA and
far western NV. The next round of Sierra snowfall is expected
Saturday afternoon and evening with a colder system providing
chances for snowfall in western NV valleys Sunday.

&&

.SHORT TERM...
Main changes to push back wind advisory starting times until late
tonight or Saturday morning and slightly bump up POP/QPF Saturday
night and Sunday morning. The main features through the weekend
will be breezy conditions later today through Saturday ahead of a
weak disturbance followed by a much wetter and more significant
disturbance/slider for Saturday night and Sunday morning.

WINDS:
Winds over the Sierra ridges have increased to 30 to 45 mph with
gusts up to around 60 mph as low pressure well off the California
coast begins to work in our direction. This is enough of an
increase that the Lake Tahoe area has seen the onset of mixing
with 10-20 mph on the lake and some winds in the 5-15 mph range
for Meyers and the Martis Valley (near Truckee). For lower
valleys, winds have remained fairly light so far with the
exception of the Surprise Valley (10-15 mph).

For the rest of today, winds aloft are not shown to increase much
more and clouds will be on the increase. Think clouds will keep
mixing down somewhat for lower valleys and winds aloft do not
look sufficient to bring widespread gusts over 45 mph. Therefore,
the wind advisory was pushed back to late tonight and Saturday as
the thermal gradient begins to tighten (and winds aloft increase)
with the incoming trough nearing the California coast tomorrow.
For tomorrow, deep southerly flow should encourage the strongest
winds in north-south facing valleys including Reno-Sparks, the
Surprise Valley and near South Lake Tahoe...with some downslope
potential (perpendicular flow over ridges there) along highway 395
in Lassen County from Janesville to Doyle.

PRECIPITATION/SNOW:
The first disturbance diving into the base of the northeast
Pacific trough still looks to elongate/split fairly significantly
as it moves into California on Saturday. This should keep any
precipitation that gets to the Sierra or northeast CA by Saturday
afternoon and evening on the light side with minimal spillover
into western NV. Still, light snow could possibly mess with travel
over northern Sierra passes by Saturday evening so be prepared if
you must travel then.

The main event in the short term comes late Saturday night and
Sunday as simulations are coming in good alignment for a slider-
type system. It is looking like a hybrid slider as models show
potential for some injection of Pacific moisture as the system's
cold pool spends some time over the extreme eastern Pacific before
moving into northern CA early Sunday. The moisture should allow
for a period of moderate snowfall in the Sierra. Out in western
Nevada, the system is plenty cold enough to bring an increasing
potential for several inches of snowfall by Sunday morning. As is
usual with slider systems, who gets the heaviest snowfall bands in
western NV is quite uncertain but simulations seem to indicate a
widespread swath of light snow early Sunday. There could also be
some lake effect snow to the south of Pyramid and Walker Lakes,
as well as Lake Tahoe, as 700 mb temps below -10C could bring
enough instability for convective snow showers off the lakes.

TEMPERATURES:
Temperatures near seasonal normals through Saturday will abruptly
fall off for Sunday with highs around 10 degrees below average.
Temperatures are expected to stay considerably below average
through next week with persistent northerly flow aloft. Snyder

.LONG TERM...Sunday night through Thursday...

A cold northerly flow will begin the week as this weekends trough
shifts east. A period of warm advection will be underway Sunday
night into Monday morning before tapering to snow showers
in the afternoon. The overnight timing of this snowfall will raise
the potential for a couple of inches of additional snowfall with
slick roadways definitely a possibility for the Monday morning
commute including lower valleys. Snow showers should diminish
by evening with only a slight chance Monday night, although some
lake effect snow may persist on the downwind sides of lakes.
Brisk northwest winds will develop especially across the Surprise
Valley, northwest NV into the Basin and Range Monday with strong
ridge winds gusting over 70 mph persisting into early Tuesday
morning as the flow turns north to northeast.

A weak shortwave ridge will move across the area Tuesday for drier
conditions and lighter winds. Mixing and ventilation will be at
their weakest Tuesday under inversions. For Wed-Thu, models continue
to drop a cold trough southward into the Great Basin with chances of
snow showers and colder temperatures. There are some timing
differences with the cold front and associated snow chances so we
made few changes to the general low chances in the ongoing forecast.
Temperatures are likely to fall well below average as 700MB temps
cool to -12 to -15C by Thursday under a cold north flow aloft. This
will put high temperatures in the 30s to lower 40s areawide. Hohmann

&&

.AVIATION...

Strong south flow ahead of east Pacific trough will keep the risk
for turbulence along the Sierra and western NV. Ridge winds will
gust 70-85 kts with surface gusts generally 30-35 kts through
tonight. As the trough moves east on Saturday, gradients will
tighten across the area with gusts increasing to 35-45kt and
becoming more widespread. Snow will reach the Sierra Crest Sat
aftn/eve and then spread into western NV late Saturday night into
Sunday morning. Snowfall amounts will range 4 to 12 inches along the
Sierra with up to 3 inches for lower elevations. Hohmann

&&

.REV Watches/Warnings/Advisories...
NV...Wind Advisory from 10 PM this evening to 4 PM PST Saturday
     NVZ005.

     Wind Advisory from 4 AM to 4 PM PST Saturday NVZ003.

     Lake Wind Advisory from 10 AM this morning to 4 AM PST Saturday
     for Lake Tahoe in NVZ002.

     Wind Advisory from 4 AM to 4 PM PST Saturday NVZ002.

     Lake Wind Advisory from 10 AM this morning to 6 PM PST this
     evening for Pyramid Lake in NVZ004.

CA...Wind Advisory from 10 PM this evening to 4 PM PST Saturday
     CAZ070-071.

     Wind Advisory from 4 AM to 4 PM PST Saturday CAZ073.

     Lake Wind Advisory from 10 AM this morning to 4 AM PST Saturday
     for Lake Tahoe in CAZ072.

     Wind Advisory from 4 AM to 4 PM PST Saturday CAZ072.

&&

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