Heavy Snow and High Wind in Nevada, December 1 to 6, 2022

Area Forecast Discussion
National Weather Service Reno NV
252 AM PST Thu Dec 1 2022

.SYNOPSIS...

A potent winter storm will bring gusty winds and heavy mountain
snow today, with rain changing to snow in lower elevations
this afternoon and producing impacts for the evening commute.
After a break in the active weather Friday into early Saturday,
another storm will bring additional snow with travel impacts from
Saturday afternoon through Monday morning.

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.SHORT TERM...

* CHANGES: Slightly lower snow totals for western NV. Otherwise,
  amounts in the Sierra look to be on track.

* SIERRA SNOWFALL: In simplest terms, travel in the warning areas
  is highly discouraged today. Once the snow gets going during the
  early morning from Tahoe northward and late morning in Mono
  county, persistent snowfall rates of 1-2"/hour are expected for
  up to 12 hours, with short bursts of enhanced 3-4"/hour rates
  possible around the time of cold front passage. Expect poor
  visibility with whiteout conditions and snow accumulating faster
  than it can be cleared. As the storm exits a bit more quickly,
  the tapering to scattered snow shower bands is expected during
  the early evening (4-7 PM) from Tahoe northward and late evening
  (7-11 PM) for Mono County, with only light additional snowfall
  after midnight in the eastern Sierra mainly south of Tioga Pass.

* LOWER ELEVATION RAIN/SNOW: For advisory areas of northwest and
  far western NV near and above 5000 feet, mostly snow is expected
  as the snow levels come down rather quickly with the cold front
  passage. For areas well north of I-80, the bulk of the snow will
  occur from daybreak through early afternoon, while for the main
  I-80/US-50 corridors the heaviest precip rates are anticipated
  during the afternoon. Farther south and east, into Mineral/Lyon
  counties, the heaviest precip is expected from near sunset
  through this evening. For areas below 5000 feet where the precip
  is more likely to start as rain, it is a bit trickier and will
  depend on how quickly snow levels fall before precipitation
  tapers off behind the cold front. WPC QPF guidance and national
  blended snow amounts have decreased a bit from previous runs.
  There appears to be enough moisture in place after the
  changeover to snow with snowfall rates sufficiently heavy to
  produce accumulations on paved surfaces even during the daytime
  hours-- similar to the snow event around Reno on November 8th.
  However, the front is accelerating and may limit the duration of
  heaviest snowfall rates. Most lower elevation sites will have a
  1-2 hour window when most of the snow will accumulate, before
  activity tapers off during the evening. The latest forecast
  indicates widespread 0.5-1" amounts for lowest elevations near
  and south of I-80 with 2-6" across far northwest NV/Surprise
  Valley and western NV foothills with a 25% chance of 2" around
  town in Reno and 50% chance of 2" at Carson City/Minden should
  some of the heavier scenarios work out. Best to go ahead and
  anticipate/prepare for slick winter travel conditions during
  the evening commute across the main urban areas.

* TEMPERATURES: A couple of very cold mornings are on tap Friday
  and Saturday with temperatures falling into teens to low 20s and
  some single digit above/below zero readings expected given
  clearing skies and fresh snow on the ground. Temperatures will
  struggle to get out of the 30s Friday.

MJD/Hohmann

.LONG TERM...Saturday onward...

Saturday morning, an upper low off the California coast will
begin to work inland, bringing impacts to the Sierra and western
Nevada. The current track brings the center of circulation onshore
near southern California late Saturday morning. With the long
residence time over the Pacific Ocean and slow progress onshore
the moisture associated with this system will be enhanced,
bringing the potential for higher snow amounts than the previous
system. Snowfall rates may be lower in comparison to the current
storm, but this storm looks to linger over the region longer. For
now, the system appears to continue to affect the Sierra and
western Nevada through Monday morning. The trajectory of the storm
appears to keep the western Nevada valleys somewhat shadowed, but
with a colder airmass, any precipitation falling would be frozen.

Ensembles reflect a 75-85% probability of a foot of snow along the
Sierra crest, with a 30-40% potential for up to 2 feet of snow to
accumulate on some peaks. In western Nevada, probabilities of an
inch of snow accumulations range 40-50%, and for 2 inches the
chances drop to 25-30%. The main message for the snow associated
with this low pressure is that it will be capable of snow for at
least a couple of days.

South-southwest winds look to amplify into Saturday morning,
bringing gusts as high as 80+ mph to the Sierra crest. Outdoor
recreation will be hampered for Saturday into Sunday, if you
consider the winds alone. Valleys east of the crest may see gusts
approach 30-35 mph for wind prone areas.

The long-lived storm will come to conclusion Monday, and the deep
diving low will carry with it some cold temperatures. It is
December, after all. Sierra communities will see daytime highs
hanging around the freezing mark, while the crest will barely make
it past the mid-twenties for highs. Western Nevada valley highs will
take a dive into the mid to upper 30s. Overnight lows along the
crest could struggle to reach 5-10 degrees, while Sierra valleys
could do a bit better with the low to mid teens. Looking down into
the lower valleys, upper teens to low 20s are in store.  HRICH

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.AVIATION...

A winter storm will bring heavy snow accumulations to the Sierra
today with some accumulation possible for lower elevations by
late this afternoon as snow levels fall. After a quick break on
Friday to Saturday AM, another potent winter storm will approach
the area and bring another round of snowfall to the Sierra and
western NV.

* Expect strong/gusty southwest winds along with LLWS and
  turbulence. Winds will be strongest through 18Z today with
  occasional gusts at or above 40 knots (80+ kts across Sierra
  ridges). Winds/LLWS will gradually back off as heavy snow ensues
  in the Sierra and behind the front (from north to south) this
  afternoon/early evening across lower elevations. The LLWS and
  brisk northwest winds will persist a bit longer (06-09Z Friday)
  in the eastern Sierra of Mono County including KMMH.

* Snow will produce IFR/LIFR conditions for the Sierra terminals
  as snow rates increase and vsbys decrease. Heaviest snowfall
  rates with substantial runway accumulations look to be in the
  16Z-24Z Thursday time frame for KTVL/KTRK and 22Z-06Z at KMMH as
  a heavier band of snowfall pushes through the area; rates of 2"
  per hour will be common with a peak of 3-4" per hour possible
  along the front. For western NV terminals, a rain/snow mix as
  early as 15Z Thu will transition to all snow during the
  afternoon hours with periods of MVFR/IFR conditions. Snow totals
  for lower elevations have decreased slightly for western NV with
  accumulations 0.5-1" more likely for lower valley airports.
  However there is a 25% chance for 2" at RNO and 50% chance for
  2" at MEV/CXP.

Hohmann

&&

.REV Watches/Warnings/Advisories...
NV...Winter Weather Advisory until 4 AM PST Friday NVZ005.

     Winter Storm Warning until 4 AM PST Friday NVZ002.

     Wind Advisory from 10 AM this morning to 7 PM PST this evening
     NVZ001-004.

     Wind Advisory until 1 PM PST this afternoon NVZ003.

     Winter Weather Advisory from 1 PM this afternoon to 4 AM PST
     Friday NVZ003.

CA...Winter Weather Advisory until 4 AM PST Friday CAZ070.

     Winter Storm Warning until 4 AM PST Friday CAZ071.

     Winter Storm Warning until 4 AM PST Friday CAZ072.

     Winter Storm Warning until 10 AM PST Friday CAZ073.

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