High Wind and Winter Weather in California, February 20, 2021

Area Forecast Discussion
National Weather Service Reno NV
250 PM PST Fri Feb 19 2021

.SYNOPSIS...

A fast-moving storm system will move over the Sierra and western
Nevada into Saturday bringing light mountain snow, valley rain and
snow showers, and breezy conditions. Warmer and drier conditions
are expected Sunday and Monday. Unsettled weather returns for the
middle of next week into the following weekend with colder
temperatures and periodic chances for snow.

&&

.SHORT TERM...

As the region waits for stronger forcing with the cold front
tonight, any showers this afternoon have been reliant on
orographic ascent up the west side of the Sierra. Thus, the only
precipitation noted is some very light snow or a mix of rain and
snow (snow level around 6500-7000 feet in northeast CA) near the
Sierra crest with roads just wet (even Mt Rose Hwy). Wind-wise,
they have been fairly well-behaved with maximum gusts so far
mainly in the expected 30-45 mph range in eastern California and
far western NV, with much lower speeds out in west-central NV
(including Lovelock, Fallon, and Hawthorne).

As the cold front approaches this evening and overnight, winds
should peak along the Sierra Front down into the eastern Sierra
along Highway 395 with gusts to 45-55 mph, possibly briefly to 60
mph, in wind-prone areas and at the mouths of canyons.

Precipitation-wise, the front blasts through and we are not
expecting heavy amounts of snow; however, there could be a couple
hours of heavier snowfall rates (perhaps 2" per hour) after
midnight near the crest from Alpine County north and west of
Susanville on Hwys 36 and 44. Across the rest of northeast CA and
for northwest NV, and Mono County near the crest, up to 2 inches
may fall (locally 2-4 inches). Some light accumulation is also
possible late tonight east of KNFL-KLOL, possibly impacting I-80
east of Lovelock and Highway 50 east of Fallon. Very little if any
precipitation is anticipated from the Sierra Front southward into
Mineral/Lyon counties and Mono County away from the crest. While
not a lot of snow, roads will be slick and hazardous where snow
does fall given the mainly overnight timing.

Temperatures will be cooler Saturday behind the front with brisk
northwest winds. Then it turns a bit milder Sunday with lighter
winds. -Snyder/X

.LONG TERM...Monday through the remainder of February...

Not much change in the extended with a couple of cold front
passages for mid-late week and maybe some snow showers for the
end of the week into the final weekend of February. Here are the
highlights:

* Monday: This is the day to get outside if you like mild spring-
  like temperatures, because it won't be this warm again until
  sometime in March. Expect light winds, sparse cloud cover and
  highs in the 50s to near 60 degrees.

* Tuesday - Wednesday: A dry cold front passage is most likely
  during the daytime hours on Tuesday, bringing an increase in
  north winds and several degrees of cooling especially north of
  US-50. The timing still could occur anytime from late morning to
  the evening, but ensemble trends appear to lean toward the
  earlier/quicker time frame. Wednesday still looks brisk and
  chilly, and while a few flurries can't be fully ruled out,
  conditions should be dry overall.

* Thursday - Next Weekend: After a short break between weather
  systems and a slight bounce back in temps on Thursday (along
  with potential for gusty west winds), medium-high confidence for
  notable cooling (highs only 30s Sierra-40s lower valleys) and a
  chance for snow showers at times Thursday night into Saturday.
  Currently it looks like a minimal-minor snow event with fast
  moving shortwaves dropping in from the north, although there are
  a handful of ensemble members that indicate more of a slider
  scenario that could bring more notable accumulations to some
  areas. Preliminary blended guidance indicates about a 10-15%
  probability of 4 or more inches around the Tahoe Basin and 2 or
  more inches for the Reno-Carson vicinity next Friday-Saturday.

MJD

&&

.AVIATION...

Breezy ahead of a frontal passage (FROPA) which is due by late
evening for northeast CA and western NV (by ~06Z/10 PM), and after
midnight for southern Mono and Mineral counties. Peak gusts to 35
kts expected at area terminals from the SW-W. A wind shear layer
near or a bit below Sierra ridge level has been observed and will
continue until after FROPA, with pockets of LLWS also possible.
Mtn wave turbulence can be expected to continue into Saturday
morning before tapering off as flow aloft turns northerly. Lighter
winds can be expected later Saturday through Sunday.

As for clouds and precipitation, widespread MVFR to occasional
IFR 06-15Z Sat in northeast CA and the Sierra with -SN/SN. Mainly
VFR in western NV with little if any precip. -Snyder/X

&&

.REV Watches/Warnings/Advisories...
NV...Lake Wind Advisory until 7 PM PST this evening for Pyramid Lake
     in NVZ004.

     Lake Wind Advisory until 7 AM PST Saturday for Lake Tahoe in
     NVZ002.

CA...Lake Wind Advisory until 7 AM PST Saturday for Lake Tahoe in
     CAZ072.

&&

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