Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 041034
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
234 AM PST Sun Dec 4 2016

.SYNOPSIS...
Temperatures will warm up today with breezy conditions ahead of the
next systems moving into the area. These first storms will bring
low end chances for showers Monday and Tuesday along with very
cold temperatures for Tuesday and Wednesday. Warmer and wetter
pattern sets up this week with increased potential for storm
systems to impact the region.

&&

.SHORT TERM...
No major changes made to the forecast through Wednesday. Storms for
Monday and Tuesday still on track with light snow showers possible
for areas mainly north of Interstate 80.

Temperatures will warm up into the mid 50s today as southwest flow
increases across the Sierra and western Nevada ahead of our first
storm. Generally wind gusts will be between 20 to 30 mph, but a few
locations could see brief gusts up to 40 mph today just ahead of the
cold front approaching the region. The main front will brush by the
northern portion of the region early Monday morning. Moisture is
still lacking with this initial cold front, but there will be enough
dynamics to produce light snow showers with it tonight through early
Monday morning for areas north of Interstate 80. Snow accumulations
are expected to be meager with up to an inch possible for some
areas. Best chances for snow will be east of the Sierra and in a
line running from northern Lassen to Pershing counties before the
front weakens and slides east.

Monday will generally be dry and cold with the majority of the snow
showers east of Fallon and Lovelock. A secondary front along with a
cold upper level low drops into the region Tuesday into Wednesday.
Forecaster confidence remains high for much colder air to inundate
the Sierra and western Nevada. Models are in decent agreement with
the timing of the front to start moving into northern Nevada
around 4AM Tuesday. The differences crop up with how the
deterministic models handle the precipitation as the front
progresses. The ECMWF holds strong with its more westward
trajectory, while the GFS and NAM show showers tapering from west
to east dramatically by Tuesday afternoon. Maintained the ongoing
forecast for light snow showers throughout the day on Tuesday with
limited accumulations. There is still a possibility for model
simulations to pick up on a more organized snow band as the event
approaches, so we will continue to monitor closely!

Bottom line: Widespread cold for early to midweek with light snow
showers Monday into Tuesday. -Edan

.LONG TERM...Wednesday through Saturday...
The focus for the long term forecast will be on the AR system for
Thursday/Friday. It is looking better organized on the models this
morning and the ensembles are also coming into a little better
agreement. It also looks to have two distinct portions, the warm
front Thursday then the cold front Thursday night into Friday. Until
it hits, Wednesday will be cold under the short wave ridge with
light east flow. Temps will be around 10 degrees below average for
highs.

Then the clouds start to arrive Wednesday night with precip
beginning with warm air advection shortly thereafter. Snow levels
will rise after the warm front moves through, but there is low
confidence on the timing of this occurring and how high they will
get. At this time, it appears they will start near the valley floors
Thursday morning then rise to near 7000 feet for I-80 south by
midnight Thursday night. Have gone with a large mixed layer for
precip at this time, but as it comes closer we should be able to
narrow it down some. Of note, it would not be surprising if Lake
Tahoe were to change over to rain before the Western NV valleys 2000
feet lower given the cold air damming ahead of the cold front.
Amounts look to be light though with the warm front.

Then the cold front arrives with snow levels falling back down to
near the valley floors sometime Friday behind it. Winds will also be
a bit breezy, but given the moisture tap a good downslope event is
not expected. The precip along the cold front is looking much better
with a moderate AR ahead of it. Precip amounts look higher this
morning and have adjusted them upward. How much snow falls depends
on the snow levels, but a foot or more could fall at pass level
above 7000 feet. Bottom line for this system, expect some travel
delays Thursday and Friday across the Sierra and Western NV due to
snowfall.

A break is expected Saturday before another system may arrive Sunday
into Monday depending on the model/ensemble member. That said, the
storm track will remain active into the west coast for a while.
However, it may remain just north of the Sierra and Western NV.

&&

.AVIATION...
VFR conditions into this evening with gusty west winds up to 25 kts
at terminals and 50 kts over the ridges. Mtn wave turbulence will
occur, but LLWS looks to be less than 20% and would most likely
affect KTVL/KTRK. Then areas of MVFR CIGS/VIS north of KSVE-KLOL
tonight in -SHSN. A break for Monday before more -SHSN possible
Monday night into Tuesday.

A larger storm is possible Thursday into Friday with CIG/VIS impacts
as well as some wind.

&&


.REV Watches/Warnings/Advisories...
NV...None.
CA...None.
&&

$$

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


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