High Wind in California, January 22, 2023

Area Forecast Discussion
National Weather Service Reno NV
241 AM PST Sun Jan 22 2023

.SYNOPSIS...

A cold front will bring increasing winds, especially to ridgetops
today, with strong and gusty east winds developing this afternoon
through Monday behind the front. Gusty winds along with frigid
wind chills will impact outdoor recreation across the high Sierra.
High pressure will then return mid to late week with a slow warming
trend, but with continued cold mornings. Valley inversions will
bring a return potential for air quality impacts.

&&

.SHORT TERM (Through Monday Night)...

Main change tonight was to bump ridge winds up along the Sierra of
Mono County through Monday and extend the lake wind advisory for
Lake Tahoe until Noon Monday.

A slider system will drop southward through the Great Basin today
and into AZ tonight and Monday. This will drag a backdoor cold
front through the area today with gusty west-northwest winds
shifting to northeast later this afternoon and tonight. Winds will
be quite strong as a northeasterly 130 KT jet impinges upon the
Sierra and thermal/pressure gradients tighten on the back side of
the upper low. 600-700 MB winds increase to 50-60 KT by this
evening and remain there through Monday morning. Ridge winds will
gust to 100+ mph at times, and with the cold temperatures, wind
chills will be quite cold tonight through Monday morning for the
Sierra backcountry, as low as -25 to -35F. If you have plans to be
in the high Sierra, be prepared for the extreme cold. Winds on
Lake Tahoe will also bring choppy conditions. For Pyramid Lake,
northwest winds will remain mostly below advisory levels, but some
chop is still expected.

Otherwise, this front will be a dry one with only a few flurries
along the eastern Sierra later today into this evening. Very cold
temperatures will settle into the region with highs struggling to
reach freezing for many areas today and Monday. By Monday night,
as winds finally settle down, clear and dry conditions will bring
a very frigid night with colder Sierra valleys once again seeing
lows drop well below zero. Also, stratus/freezing fog may begin to
return, especially to the Mono Basin, as inversions strengthen.

Hohmann

.LONG TERM (Tuesday through Sunday)...

At the start of the period, longwave ridging looks to rebuild behind
the inside slider with mostly tranquil conditions through the
remainder of the work week. Light easterly winds will be in place
thanks to the west-east pressure gradient. In the mountains,
temperatures will generally be near average. In the lower elevations
where inversions are likely to develop, temperatures will remain
cold, relatively speaking. Conditions will be favorable for
freezing fog, low stratus, and possible degraded air quality in
the valleys. The exception will be on Thursday where some guidance
wants to retrograde a trough through SoCal on the south side of a
high pressure located over OR. In this scenario, a brief period
of gusty easterly ridgetop winds to 50-70 mph and better
mixing/ventilation in the low levels may help to limit air quality
concerns.

While models keep any chance of atmospheric rivers at bay until at
least the beginning of next month, we could still see some active
weather next weekend... Cluster analysis valid next Saturday reveals
approximately 50% of ensemble members hinting at a westward shift of
the longwave ridge, compared to the multi-model mean. This will
place W NV and NE CA in a more favorable trajectory that would allow
it to be impacted by equatorward moving area of low pressure and
affiliated moisture coming out of B.C. This scenario is supported
mostly by the Canadian and European ensemble systems, with the GEFS
leaning towards a less amplified regime and ridging remaining over
our area, keeping the storm track over eastern Nevada to Four
Corners region. With the operational GFS even showing at least some
QPF passing through the region, and ECMWF being much wetter, have
taken the national blend's guidance and bumped it up slightly to
include at least the mention of snow showers in the mountains
Saturday night through Sunday. Not surprisingly, this would bring an
uptick in ridgetop winds as well. In any case, it's highly dependent
on whether we see that westward shift of the ridge and amplification
of the trough or not. Something to keep an eye on if you have plans
in the mountains next weekend (like I do).

-Dustin

&&

.AVIATION...

* A cold front will move through western NV and eastern Sierra
  this morning with gusty northwest flow at ridge level or near
  FL100, shifting to the northeast this afternoon and remaining
  quite strong through Monday. Ridge level winds will generally
  see gusts into the 40-55 kt range in western NV and close to 90
  kts near the Sierra crest. Surface winds will increase to
  northwest or north 10-15 mph today with some gusts 20-25 kts,
  highest gusts along the eastern Sierra of Mono County and points
  east into Mineral County (KMMH-KHTH). Moderate turbulence and
  periods of LLWS at Sierra airports will create bumpy flying
  conditions through Monday.

* Some low clouds may bank against the eastern Sierra between
  KMEV-KMMH this afternoon and evening with a few snow flurries.
  Some terrain obscurement is possible during this time.

* High pressure returns much of the week Tue-Fri with valley
  inversions and the possibility of low stratus and freezing fog
  returning to some Sierra valleys.

Hohmann

&&

.REV Watches/Warnings/Advisories...
NV...Lake Wind Advisory from 1 PM this afternoon to noon PST Monday
     for Lake Tahoe in NVZ002.

CA...Lake Wind Advisory from 1 PM this afternoon to noon PST Monday
     for Lake Tahoe in CAZ072.

&&