Area Forecast Discussion
Issued by NWS Reno, NV

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182
FXUS65 KREV 272231
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
231 PM PST Sun Nov 27 2016

.SYNOPSIS...

Another round of lighter snow is expected late tonight into
Monday morning as a system brushes by over northeast Nevada. Much
colder air settles over the region through the week. Additional
light snow is possible Wednesday night and Thursday along with a
reinforcing shot of cold air.

&&

.SHORT TERM...

The next system is mainly one of warm air advection and will move
south across the basin and range later tonight into early Monday.
Models have been fairly consistent with this feature over the past
couple of days...placing the best forcing and moisture over the
eastern part of the forecast area. The forcing is actually better
with this wave than the previous storm in western Nevada...but
the moisture is far less impressive. Snowfall of up to an inch
should be common east of Highway 95 with a few spots in far
eastern Churchill and Pershing counties receiving as much as 4
inches. A couple of inches is also possible over far northern
Washoe County above 5000 feet. A couple of inches is possible at
lake level in the Tahoe basin and above 7000 feet in Mono County
with slightly higher totals near the crest. This storm is moving
through just before or during the morning commute. We considered
an advisory just for that reason but have opted for a Special
Weather Statement. Travel can become hazardous with less than an
inch of snow so we will try to get the word as efficiently as
possible with graphics and statements and leave the advisories to
more widespread 1-2+ inch events.

Winds should become gusty behind this system. A 150 knot jet
oriented north to south and strong pressure gradient behind the
wave could lead to very strong winds in the Surprise Valley and
northern Washoe County where some minor downslope enhancement is
also possible. Gusts in excess of 60 mph are possible there before
daybreak Monday so we have issued a High Wind Warning to replace
the High Wind Watch. Farther south gusty winds are also possible
in the Tahoe Basin and along the Sierra Front. Gusts to near 45
mph are possible briefly Monday morning after the snow ends; a
few wind prone locations may reach up to 55 mph. Lake Wind
Advisories are in effect for Lake tahoe late tonight into early
Monday and Pyramid lake during the day Monday for increasing
west-northwest winds.

We get a brief break Monday night into early Wednesday as
ridging starts to develop. This will bring much colder lows to
the valleys and develop valley inversions. Gusty northeast winds
are likely over the Sierra Crest Tuesday morning. Valley
inversions should get scoured out by late Wednesday ahead of
another fast moving short wave trough.

This wave will bring another round of precipitation to the region
Wednesday night...but the fast movement and lack of moisture
should keep snowfall to a minimum. 20

.LONG TERM...

A cold upper trough with an inland trajectory will provide another
reinforcing shot of cold air Thursday as a back door cold front
pushes across western Nevada. Light snow showers will be possible to
valley floors mainly across Pershing, Churchill, and Mineral
counties Thursday afternoon with light upslope forced snow showers
along the eastern Sierra in Mono County. Did not increase
precipitation chances appreciably as ensemble spreads are fairly
large and global models have trended to not dig the trough as far
westward as previous runs.

As the the trough swings through the region, the backside jet will
introduce strong northeast winds aloft which will produce gusty
winds along the Sierra and potentially along the west slopes. These
winds have the best potential of mixing to lower elevations by
Friday morning where gusty winds from the more uncommon east
direction may produce choppy conditions from mid-lake to west shores
on Tahoe through early Friday afternoon. The backside jet will
quickly drop south through Mono County by Saturday morning with
ridges beginning to settle down as upper level ridging builds
through the remainder of the weekend.

Ridging will allow higher elevations to warm faster than valley
locations through Sunday as inversions strengthen under the building
ridge. Temperatures will return to seasonable values by the end of
the weekend with highs in the upper 40s to near 50 across Sierra
valleys and western Nevada.  There is a potential for another low
pressure system to approach far northeast California and northwest
Nevada Sunday night into Monday but there is quite a bit of model
discrepancy and model spread at this time and will maintain just low
end chances for precipitation. Fuentes

&&

.AVIATION...

A shortwave trough will bring another round of light snow and gusty
winds through Monday morning.

The next round of snow showers will approach the I-80 corridor
roughly between 10pm and midnight tonight with the bulk of the snow
showers pushing south of KRNO, KCXP, KTRK, KTVL by 4-5am Monday
morning. Accumulations look light and looking generally at trace to
less than an inch for KRNO and KCXP with 1-2" possible for Sierra
terminals KTRK and KTVL. Locations farther east such as KNFL and
KLOL may see a bit better chances to see up to an inch of snowfall
through Monday morning. Timing for snow at KMMH looks to be
generally in the 2am-6am timeframe with generally less than 1 inch
expected.

The other operational impact will be strong and gusty winds as winds
on the backside of the trough start ramping up across the ridges
late this afternoon and evening before peaking early Monday morning.
This pattern will likely set up a concern for low-level wind shear
and turbulence along the Sierra. This setup would provide sustained
winds near Sierra ridgetop (10,000`) level near 60kts with times of
calm winds at valley floors. These calm winds at the surface may see
sudden breaks where mixing of the higher winds aloft will create
sudden peaks and lulls in the valleys with winds gusts of 40-45
knots possible KRNO, CXP, KTRK, KTVL Monday morning as early as 3-
4am. Gusty conditions for these terminals should begin to diminish
by late Monday morning. KMMH will also see gusty winds in the 30-
35kt range Monday morning. Fuentes

&&

.REV Watches/Warnings/Advisories...
NV...Lake Wind Advisory from 6 AM to 6 PM PST Monday for Pyramid
     Lake in NVZ004.

     High Wind Warning from 1 AM to 10 AM PST Monday NVZ005.

     Lake Wind Advisory from 1 AM to 10 AM PST Monday for Lake Tahoe
     in NVZ002.

CA...High Wind Warning from 1 AM to 10 AM PST Monday CAZ070.

     Lake Wind Advisory from 1 AM to 10 AM PST Monday for Lake Tahoe
     in CAZ072.

&&

$$

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



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