Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 172224
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
324 PM PDT Tue Oct 17 2017

.SYNOPSIS...

Warm days and dry conditions will persist through early Thursday.
A modest system will bring gusty winds Thursday and Thursday
night, with light valley rain and mountain snow Thursday night
into Friday, mainly in the Sierra and north of Interstate 80.
Warmer and drier conditions are expected for the weekend and into
next week.

&&

.SHORT TERM...

Main forecast changes:

- Raised winds considerably Thursday and Thursday night, especially
  north of Highway 50.
- Trimmed POP for portions of western and west-central NV as well
  as Mono County Thursday night and Friday morning.

Tranquil weather under a ridge of high pressure is on track through
Thursday morning. Some light haze, with a modest reduction in air
quality, could remain around portions of eastern CA and western
NV through tomorrow as flow aloft brings in some smoke particulates
from northern CA fires.

Low pressure will approach the Pacific Northwest coast Thursday and
push a cold front into northern California, with the front pushing
through most of the region by Friday morning as the low moves
into the far Northwest CONUS. This will bring gusty winds to the
region, especially near and north of Highway 50. Simulated
soundings indicate mixing (and moisture) to just above 700 mb
from around I-80 south, with mixing up to 600 mb across northern
Washoe and Lassen Counties closer to the low`s cold pool. Winds at
the top of the mixed layer are simulated to reach 50-60 kts ahead
of the front, which should translate to wind gusts up to 60 mph in
the foothills along and west of Highway 395/I-580 from the
Antelope Valley northward to Susanville. For valleys (generally
along and north of Highway 50) wind gusts 40-50 mph are reasonable
by late Thursday afternoon and early Thursday evening given the
winds in the mixed layer, with another brief shot of strong gusts
with FROPA. With all this in mind, wind advisories have been
issued for northeast CA and far western/northwestern NV.

As far as precipitation, the system is a a glancing blow and
moisture looks fairly shallow (only to ~700 mb from I-80 south) so
precipitation looks generally light with strong shadowing in the
lee of the Sierra. Amounts in the lee of the Sierra are expected
to remain 0.05" or less, with up to a few tenths north of I-80
near the crest. Snow levels will be falling with the front and the
main precipitation is expected overnight into Friday morning;
therefore, a light snowfall is possible Thursday night over
Donner Summit and into northeast CA above about 5500 feet
(including portions of Hwys 44/36). If you are traveling in those
areas Thursday night or early Friday, pay attention to the latest
forecasts as some delays are possible. -Snyder

&&

.LONG TERM...Saturday through Tuesday...

The long term forecast turns much quieter as models are in very
good agreement with building in a strong ridge of high pressure.
This means valley inversions will become strong with temperatures
similar for Sierra and lower valleys. Despite the strong ridge,
highs are expected to top out near or slightly above average (+5
degrees) for valleys given the lack of mixing under the ridge.
-Snyder

&&

.AVIATION...

VFR conditions with generally light winds (under ~8 kts) for
valleys through Thursday morning.

Winds will increase Thursday afternoon into Thursday night as a
cold front approaches. Some LLWS is possible Thursday night in
valley areas where winds drop off to less than 10 kts, with
turbulence above valley floors a given as sustained Sierra ridge
winds exceed 40 kts. Some MVFR CIGS are possible in the Sierra
with -RA at terminals after 06Z Friday night. ??/Snyder

&&

.FIRE WEATHER...

Poor humidity recovery on mid-slopes and ridges expected again
tonight before moisture increases ahead of an incoming low pressure
system on Thursday. Strong and gusty winds are expected late
Thursday into Thursday night with critical conditions possible for
the Eastern Sierra for portions of Alpine and Mono counties.
Relative humidity could fall into the 10 to 15% range Thursday
afternoon with wind gusts reaching 35 mph in Mono County. The
peak winds with this storm are expected Thursday evening and
overnight.

Stronger winds are expected farther north across the Tahoe Basin and
roughly north of Highway 50 through western Nevada. Winds will
increase late morning with valley locations seeing a 3-6 hour period
of wind gusts in the 40 to 50 mph range early Thursday evening.
Winds will remain strong overnight and into Friday morning mainly
across foothills and mountain areas where wind gusts up to 60 mph
will possible with ridgetops seeing gusts near 100 mph. A secondary
increase in wind gusts are possible as a cold front moves through
Thursday night.

Increased moisture is expected across these areas but the magnitude
of the gusts may still present some concerns for carrying fire in
lighter fuels late Thursday afternoon and early evening. Localized
wetting rains will be possible Friday morning in the Sierra north of
Lake Tahoe to the Oregon Border. Fuentes

&&

.REV Watches/Warnings/Advisories...
NV...Wind Advisory from 3 PM Thursday to 5 AM PDT Friday NVZ005.

     Lake Wind Advisory from 11 AM Thursday to 5 AM PDT Friday for
     Lake Tahoe in NVZ002.

     Wind Advisory from 3 PM Thursday to 5 AM PDT Friday NVZ003.

     Lake Wind Advisory from 11 AM to 8 PM PDT Thursday for Pyramid
     Lake in NVZ004.

CA...Wind Advisory from 3 PM Thursday to 5 AM PDT Friday CAZ070-071.

     Fire Weather Watch from Thursday afternoon through late Thursday
     night CAZ273.

     Lake Wind Advisory from 11 AM Thursday to 5 AM PDT Friday for
     Lake Tahoe in CAZ072.

&&

$$

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


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