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Area Forecast Discussion
National Weather Service Reno NV
306 PM PDT Sat Oct 22 2016


Breezy conditions will develop across the region Sunday and Monday
as low pressure approaches the West Coast. The low will bring light
to moderate rain to the northern Sierra and northeast California
Monday afternoon into Tuesday. There is potential for more widespread
rain with high elevation snow late Thursday into the weekend.
However, forecast confidence in those scenarios remains low.


.Short Term (through Tuesday)...

Primary focus is on wind and rain potential with incoming Pac NW
storm Sunday through Tuesday. Overall impacts from precipitation
in our region are low, however wind impacts will be moderate.

* Pressure gradient plus increased flow aloft will result in
  enhanced southerly winds Sunday and Monday. Direction will favor
  north-south oriented valleys. Sunday's winds will focus more in
  areas south of Highway 50, where lower elevations of Mono County
  will see critical fire weather conditions. Gusts 30-40 mph will
  be common. Monday the strong winds will be more widespread due
  to ideal phasing of the gradient and flow aloft. Gusts 35-45 mph
  areawide with higher winds north of a Susanville to Gerlach
  line. Typical impacts both days from breezy winds -- tricky
  travel for high profile vehicles, rough water on lakes, and
  turbulence for aviators.

* This storm looks to be heavily shadowed with a south flow so
  the most meaningful precipitation will be in the Sierra from
  Tahoe northward to western Lassen County where 0.5 to 1" of rain
  is projected from Monday afternoon through Tuesday. A few stray
  showers are possible elsewhere in the Sierra and W Nev on Monday
  but amounts will be quite light. With snow levels above most
  passes, we expect impacts to be mainly areas of heavy rain and
  reduced visibility slowing traffic in the N Sierra.


.Long Term (Tuesday Night onward)...

Tuesday night through Wednesday night, flow aloft pivots to a
more southerly direction as the eastern Pacific trough reloads
with a disturbance/low off the California coast. This will bring
precip-free conditions for the eastern Sierra and western Nevada.
Temperatures will remain relatively mild with most spots outside
of colder Sierra valleys remaining above freezing overnight.

Thursday and Friday, the 12Z ECMWF has thrown a wrench in the
works as it ejects the upper low a solid 12-18 hours faster than
its 00Z run and the GFS. Also, uncertainty arises regarding
precipitation placement due to location discrepancies with a deep
moisture feed ahead of the disturbance. Currently, the area of
most precipitation uncertainty Thursday into Friday appears to be
far western NV. If the moisture tap goes into central NV and the
negative-tilt upper low moves into northwest CA, then portions of
western NV may be get the short end of the stick precipitation-
wise. With all this in mind, POP was not changed much Thursday and
Friday as we await a clearer picture.

Turning to next Friday night and Saturday, the last two runs of
the EC and GFS actually come back in line to a large degree as the
region sees a lull before the next trough moves ashore. This most
likely means a break in any substantial precipitation with
continued mild temperatures with no colder air to speak of behind
Friday's trough. Snyder



With VFR conditions expected through at least Monday morning for
northeast CA, the eastern Sierra and western NV the main concern
will be wind.

Wind gusts 25-35 kts are expected Sunday and Monday afternoon and
evening for Sierra and far western Nevada terminals, highest in
north-south valleys (including KRNO/KTVL). A few higher gusts to
40 kts are possible in and near the Sierra foothills, most likely
on Monday. Out in west-central NV, gusts are expected to top out
in the 25-30 kts range.

As far as turbulence and shear, winds aloft will not be overly
favorable (more south than west) Sunday for mountain wave
turbulence. However, winds will turn more westerly Monday bringing
the potential for stronger turbulence in the lee of the Sierra.
Mechanical/mixing turbulence will be a given each afternoon
through Monday. There will also be a chance for a shear layer
(mainly speed shear) over Sierra and far western NV terminals
within 2,000 feet AGL Monday morning (until mixing destroys the
layer). Snyder


.REV Watches/Warnings/Advisories...
NV...Wind Advisory from 11 AM to 8 PM PDT Monday NVZ005.

     Lake Wind Advisory from 11 AM to 8 PM PDT Sunday for Lake Tahoe 
     in NVZ002.

     Lake Wind Advisory from 11 AM to 8 PM PDT Monday NVZ002.

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

     Lake Wind Advisory from 11 AM to 8 PM PDT Monday NVZ004.

CA...Wind Advisory from 11 AM to 8 PM PDT Monday CAZ070-071.

     Red Flag Warning from 11 AM to 6 PM PDT Sunday CAZ273.

     Lake Wind Advisory from 11 AM to 8 PM PDT Sunday for Lake Tahoe 
     in CAZ072.

     Lake Wind Advisory from 11 AM to 8 PM PDT Monday CAZ072.



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