Snow Squall Warning 2, NWS Reno, NV

Area Forecast Discussion
National Weather Service Reno NV
208 PM PST Wed Jan 10 2024

.SYNOPSIS...

A cold front will bring continued strong winds and periods of
heavy snow to the region through this evening. Expect rough travel
through Thursday morning. Much improved weather is forecast
Thursday afternoon through Friday mid-day, though temperatures
will be rather chilly. Our next storm moves in Friday evening into
Saturday with mountain snow and valley rain/snow showers.
Conditions next week are trending drier with a slow warming trend.

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.DISCUSSION...

* No major changes to the forecast and messaging for our ongoing
  winter storm with widespread strong winds and bands of heavy
  snow through this evening. Going to be rough travel for many.
  Radar & wind observations are lining up more or less with the
  latest high-res guidance.

* We're mainly concerned about potential boom scenarios where
  snowfall rates of 1-2"/hour in W Nevada from through 9 PM could
  yield some impressive totals and hit warning criteria in some
  areas. HREF really hitting areas east of Susanville to
  Winnemucca along with Fernley-Fallon-Hawthorne-Yerington areas
  for excess of 6".

* Reno-Carson still have potential for 4"+ with NBM showing 60%
  odds of that level for some of the Sierra Front. HREF showing
  high probability for 2-3"/hour in the Sierra including around
  Donner Pass through 8 PM and Tioga-Mammoth areas 6 PM to
  Midnight. Blowing snow will be a factor, producing low
  visibility. Can't rule out thundersnow even in W Nevada with
  steep lapse rates in FV3/HRRR.

* Cold & dry airmass moves in rapidly by daybreak tomorrow.
  However travel for the AM commute will be sketchy with snow and
  ice slow to melt on untreated roads/walkways. Quiet weather
  with upper ridge Thursday into Friday mid-day.

* Next storm has shown a little more spice in latest simulations
  for Friday evening into Saturday with the NBM 75-90th percentile
  "boom" scenarios showing 2-3 feet of snow for Sierra crest. A
  touch warmer storm with rain-snow lines anywhere from
  5500-7000', so travel impacts for ski traffic Friday evening
  into Saturday will be considerable. Light rain showers and
  breezy winds for W Nevada valleys are a good bet especially for
  Saturday.

* Next week, even starting Sunday, is trending drier with
  gradually warming temperatures in latest NBM guidance. That
  being said, there's still a signal for a potential storm
  Tuesday-Wednesday next week. Nothing big by January standards:
  light-moderate mountain snow, light rain showers and breezy
  winds in valleys.

-Chris

&&

.AVIATION...

* Rough day and night ahead for flying in the region with
  impressive cold front bringing widespread strong W/NW winds and
  turbulence/shear, along with periods of heavy snow including W
  Nevada airfields. Periods of IFR/LIFR conditions in snow squalls
  are likely based on latest HRRR/HREF guidance, especially
  between 23z-04z, including RNO/CXP/MEV/NFL/HTH. Runway
  accumulations a good bet, with snowfall rates potentially
  1-2"/hour at times.

* Thursday is looking much better with a high pressure ridge
  working in aloft along with lighter winds. Drier air should also
  result in mainly scattered clouds. Cold air will help keep non-
  treated surfaces snowy and icy into Thursday.

-Chris

&&

.AVALANCHE...

* Ongoing winter storm continues, with impressive snowfall rates
  likely in the Sierra, 2-3"/hour along the crest and even into
  Tahoe basin and E Sierra communities at times. Enough
  atmospheric instability present for thundersnow/lightning. This
  along with strong winds will make for dangerous whiteout
  conditions. Sierra crest gusts over 100 mph certain, with gusts
  into the 40s/50s possible for mountain valleys at times.

* SWE projections for this storm did tick up over past 24 hours
  worth of models. Now showing 1.5-2" along crest west of Tahoe,
  0.5-1" along east side of Tahoe and for the crest areas in Mono
  Co. Snow density will be low, lots of blowing, with ratios
  14-20:1 in the mountains.

* Well below normal temperatures Thursday will rebound Friday
  ahead of our next storm which is trending more interesting
  snow-wise for Friday evening through Saturday.

* Still lots of variability with that storm, as NBM 25th
  percentile is showing barely a few inches of snow along the
  crest while 75th percentile has 2-2.5 feet! "Best guess" on SWE
  is 1-2" along crest, with 0.5-1" for east side mountains.
  Warmer storm with snow lines 5500-7000' and snow ratios closer
  to "average" 10-12:1. Hard to call on the winds with the model
  variability, but probably safe to assume another round of strong
  gusts on Sierra ridges Friday afternoon into Saturday with NBM
  showing 70%+ gusts 60 MPH or higher.

-Chris

&&

.REV Watches/Warnings/Advisories...
NV...Winter Weather Advisory until 10 PM PST this evening NVZ003>005.

     Winter Storm Warning until 1 AM PST Thursday NVZ002.

     Winter Weather Advisory until 1 AM PST Thursday NVZ001.

CA...Winter Weather Advisory until 10 PM PST this evening CAZ070-071.

     Winter Storm Warning until 1 AM PST Thursday CAZ072.

     Winter Weather Advisory until 4 AM PST Thursday CAZ073.

&&