Area Forecast Discussion
Issued by NWS Reno, NV

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000
FXUS65 KREV 221027
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
227 AM PST Mon Jan 22 2018

.SYNOPSIS...

A weak disturbance will bring very light snow for parts of eastern
California this morning. A stronger and colder storm is expected
late Wednesday into Thursday, bringing windy conditions and more
snow to the Sierra and possibly to lower elevations, with travel
impacts expected. Generally drier conditions then return for next
weekend with mild temperatures.

&&

.SHORT TERM...

Weak shortwave with shallow moisture will keep areas of very
light snow going across the eastern Sierra, northeast CA and far
northwest NV this morning, with precip decreasing this afternoon.
Additional accumulations in these areas will generally be less
than 1 inch, with locally up to 2 inches possible. Very little to
no precipitation is expected for western NV south of Gerlach, and
the eastern half of Mono County.

From tonight through Tuesday night, flat ridging will keep overall
dry conditions across the region with mainly light winds except
for some increasing ridge level winds by Tuesday night. Cloud
cover will be most widespread north of I-80 while temperatures
edge upward into the lower 50s for most valleys along and south of
I-80.

The main weather event this week will be a fast moving and cold
storm system bringing a period of strong winds primarily Wednesday
afternoon and evening, followed by a round of moderate to heavy
precipitation (mainly snow) Wednesday night. Anyone planning
travel over the Sierra late Wednesday into Thursday morning should
expect slick winter conditions, while western NV could also see
some light snow accumulations affecting the Thursday morning
commute.

Current projections for Wednesday`s winds support peak gusts of
45-55 mph for lower elevations, with possible gusts up to 70 mph
for wind prone areas of far western NV. Sierra ridge gusts may
surpass 100 mph with forecast 700 mb flow of 50-60 kt. This looks
to be a similar to last Thursday`s wind event, with a relatively
short period (3 hours or less) for these maximum wind speeds.

As has been the case with recent storm systems, the short
duration of the heaviest precip will again be the limiting factor
to total snow amounts Wednesday night into early Thursday,
although snowfall rates could briefly peak at 2-3" per hour for
the eastern Sierra. With a colder start, snowfall amounts between
5500-7000 feet in eastern CA including lake level around Tahoe (and
also above 7000 feet for Mono County) have a better chance of
reaching the 6-12 inch range, while up to 18 inches are possible
above 7000 feet from Tahoe northward. East of the Sierra, amounts
will be far less but there is a possibility for a couple inches
below 5000 feet in northeast CA and far western NV including the
urban areas, with up to 6 inches for foothills above 5000 feet.
MJD

.LONG TERM...Thursday through next weekend...

The area will be underneath a cold upper trough Thursday with
model soundings indicating unstable conditions. Models have been
consistently showing snow showers regenerating Thursday afternoon,
especially from the Tahoe Basin northward. Some of these snow
showers could be heavy and produce local amounts to several inches
Thursday afternoon/evening. Snow showers will be more isolated to
scattered elsewhere with light accumulations possible once the
sun angle gets low enough. Hazardous driving conditions will
persist in the Sierra and northeast CA, while spotty slick
conditions could develop in lower elevations where snow showers
occur after sundown and close to the Thursday evening commute.
It will remain blustery and cold Thursday with high temperatures
in the lower 30s near the Sierra and upper 30s to mid 40s in
western NV.

The upper trough will begin to exit Friday with snow showers
retreating to the north and ending in most areas. High pressure
will then build into the southwest U.S. and bring a dry and milder
pattern as we go through next weekend. The ridge will be rather
flat as shortwave energy moves through the Pacific Northwest.
There could be a few light showers near the Oregon border but the
bulk of the precipitation will remain north across Oregon/Idaho.
Temperatures will remain quite cool Friday before trending back up
to near or slightly above normal by Sunday. Some guidance sources
have temperatures pushing 60 degrees in lower valleys, although
extensive cloud cover may be a mitigating factor. Hohmann

&&

.AVIATION...

Light snow showers may briefly reduce cigs/vsbys in the Tahoe Basin
this morning with some light accumulation possible at KTRK/KTVL.
Otherwise VFR conditions will prevail today. Gusty ridge winds to 50-
55 kts this morning may result in some turbulence but these winds
are expected to decrease during the afternoon as 700 mb flow
decreases to 15-20 kts.

Some patchy freezing fog is possible for Sierra valleys late tonight
and Tuesday morning as skies clear. Otherwise conditions will be
quiet for aviation Tuesday. A strong cold and fast moving storm
will bring gusty winds and turbulence/possible LLWS Wednesday,
followed by a good chance of accumulating snow Wednesday night into
Thursday. Snow accumulation is likely for Sierra terminals while
confidence is lower for snowfall accumulation amounts at lower
elevation sites. Right now, due to the fast movement of the cold
front, accumulations for western NV airports are expected to
remain 2 inches or less. Hohmann

&&


.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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