Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 032231
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
231 PM PST Sat Dec 3 2016

.SYNOPSIS...

Temperatures will warm on Sunday with breezy conditions ahead of
the next systems moving into the area Monday and Tuesday. These
systems will bring low end chances for showers Monday and Tuesday
along with very cold temperatures for Tuesday and Wednesday. A
warmer and wetter pattern sets up by the end of the week.

&&

.SHORT TERM...

Southwest winds will begin to increase Sunday and will likely be
strong enough to scour most valley inversions with high
temperatures jumping above normal. These winds are increasing
ahead of a cold front, so this warmth will be short-lived. This
initial surface front has trended weaker with a fairly shallow
depth to the colder air, therefore the initial cooldown will not
be as great as previously forecast. The moisture along the front
will be an extremely narrow band with significant drying right
behind the front. The frontal dynamics will help with shower
development, but don`t expect much in the way of accumulation due
to the limited moisture. Showers will be hit or miss with the
places that see snow only receiving a trace up to an inch. The
current trajectory will likely put the best chances in central and
eastern Nevada rather than the Sierra.

The stronger secondary front and associated cold upper trough will
push into the region from the north Tuesday into Wednesday.
Deterministic forecast models and ensembles are in good agreement
in a major cool down, but still differ in the placement of the
stronger wave on the backside of the low, which has implications
on precipitation potential. Have kept the forecast trended toward
the more consistent EC which has an inside slider track. This
keeps chances for light snow showers in the forecast throughout
the day on Tuesday. Again, moisture is limited so totals will be
light, generally a trace up to a couple inches. However, if a more
organized snow band sets up, there is a possibility for locally
higher amounts. -Dawn

.LONG TERM...Wednesday through Saturday...

There weren`t too many changes made to the existing forecast. Models
still have the idea of a break in precipitation for Wednesday with
cold temperatures Wednesday and an approaching weak-to-moderate AR
for the end of the week. While there are some timing differences
between the EC and GFS, both are beginning to show two distinct
waves with more of a middling trajectory towards the southern
Cascades. Even though this isn`t the most favorable position for
heavy snow in the Sierra, a decent plume of moisture is expected to
move through the region with periods of spill-over into Western
Nevada.

Model timing for the initial wave has sped up by about 12 hours from
previous runs with precip moving into the Northern Sierra by
Thursday afternoon. However, have kept timing of onset unchanged to
late Thursday evening into Friday since this is the first trend to
an earlier onset. If subsequent runs favor the trend of an earlier
onset, the forecast will be adjusted.

Snow levels remain a large question, especially considering the
unseasonably cold air mass that is expected to be over the region
with warmer flow aloft. This scenario often leads to a mixed bag of
precipitation where some valleys mix out while cold air remains
locked in others. With cold-air damming in the past, Western Nevada
valleys have remained cold with all snow while Sierra valleys mixed
out with rain occurring. It is sufficient to say that confidence is
low on precipitation type and timing of expected snow level
changes. Also, precipitation totals are quite indeterminate at
this time considering the uncertainties mentioned above. What can
be said with a degree of confidence: there will likely be periods
of travel impacts in, around, and outside of the Sierra from late
Thursday into the weekend. Boyd

&&

.AVIATION...

VFR conditions with lighter east winds today and tonight. Some west
winds gusting to 25 kts Sunday in the valleys and up to 50 kts on
the ridges with some mtn wave turbulence ahead of the next cold
front. At this time, do not expect significant LLWS. Some snow
showers are possible at the terminals Monday afternoon into
Tuesday.

&&

.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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