Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 131013
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
313 AM PDT Fri Oct 13 2017

.SYNOPSIS...

Below average temperatures are on tap through Saturday as a trough
moves over the West. Strong easterly winds are likely at the
northern Sierra crest late tonight and Saturday morning as strong
surface high pressure builds into the Great Basin. Warmer
temperatures and dry conditions are expected early next week, with
the potential for cooler, wetter, and windier weather late week.

&&

.SHORT TERM...

Low pressure currently near the Washington coast will drop into
eastern Oregon by this evening. With the upper forcing remaining
near or north of the Oregon-Idaho-Nevada border, showers should
remain restricted mainly to Humboldt County and points east, with
just a few light showers working into far northern Washoe County
by this evening.

Although most of northeast CA and western/west-central NV will
avoid precipitation with the upper low, the low will push a shot
of cool air into valleys, with little temperature change for the
high Sierra given a fairly shallow push of colder air (deeper cold
air over northern and eastern NV). The push of cooler air into
the western Great Basin is expected to stack the thermal gradient
across the Sierra sufficiently to bring a short period of stronger
winds to the northern Sierra crest. While nothing remarkable for
the area, winds are expected to gust to between 60-80 mph over the
Tahoe crest between about midnight and mid-morning Saturday.

For valleys in western NV, there could be a short period with
winds gusting to 20-30 mph this evening and overnight as the
surface high builds in. This will cause some chop on Pyramid Lake,
especially with northerly flow, but will occur mainly near or
after sunset when the lake is closed to the public. Therefore, no
lake wind advisory is expected at this time.

Saturday will bring cool air with highs 10-15 degrees below average
(mainly 50s in the valleys). Sunday, highs rebound to near or
slightly below average as a strong ridge builds in aloft. With
light flow under the ridge, lower valley inversions are simulated
to remain rather strong with limited mixing depth. This is
expected to bring similar high temperatures for Sierra valleys and
lower valleys on Sunday (60s). -Snyder

.LONG TERM...Monday through next week...

Monday, a ridge of high pressure over the Great Basin is expected
to persist one last day, providing near average temperatures to
the west NV/east Sierra region along with light winds. By Tuesday,
the ridge shifts east and a dry zonal flow aloft is expected to
set up. Thus, expect Tuesday afternoon temperatures to again be
around average along with westerly afternoon breezes in the lee
of the Sierra.

For midweek, computer guidance still shows a change to a more
energetic weather pattern over north CA/NV as a jet aloft drops
south out of the Pacific Northwest. Computer guidance may be
converging on a Wednesday night/Thursday arrival of the storm for
the northeast CA/east Sierra/west NV region. The best chances for
precipitation through the end of the week look to be mainly north
of Highway 50. Impacts by Wednesday night/Thursday could be strong
winds with dry humidities east of the Sierra crest and possible
moderate rain in the Sierra from the Tahoe Basin northward. By the
end of the week snow levels could lower significantly, especially
north of I-80. Hopefully forecast confidence will increase over
the next couple of days, so these potential threats can then be
described with more detail. JCM

&&

.AVIATION...

Expect increasing northwesterly surface winds this afternoon due to
a cold frontal passage. The strongest winds will be north of I-80
where surface gusts are likely to reach 20-25 kts. There may also be
a brief period of low level wind shear this evening as post-frontal
surface winds trend to northerly while low-level winds aloft remain
westerly 25-35 kts. By Saturday, easterly flow returns with gusts
across Sierra ridges possibly reaching 50-65 kts. JCM

&&


.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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