Avalanche and Heavy Snow in California, March 1, 2023

Area Forecast Discussion
National Weather Service Reno NV
225 PM PST Tue Feb 28 2023

.SYNOPSIS...

The final round of snow will continue to produce widespread travel
impacts into tonight, then diminish to lighter snow showers
overnight through Wednesday. Gusty winds will produce blowing snow
and blizzard conditions with sub-zero wind chills at times across
the Sierra. A short break in storm activity will close out this
week with snow chances returning this weekend.

&&

.SHORT TERM...through Wednesday Night...

The snow continues to pile up in impressive fashion for the
Sierra, as this week-long series of storms has produced 5-9 feet
of snowfall as of this morning in higher elevations, and 2-5 feet
for the Tahoe basin and portions of northeast CA. Season to date
totals are surpassing 500 inches in several sites near the Sierra
crest! The final chapter of this storm will roll through during
the remainder of today and tonight, with convectively-enhanced
snow bands generating another 1-2 feet in the areas currently
under a Blizzard Warning. Many major travel routes through the
Sierra remain closed, and travel is not recommended until roads
can be cleared and reopened, which could take a few days in some
cases--especially for Mono County.

Lower elevations will also be affected by this final push of snow
this evening, with 2-6" in the warning areas of northeast CA-far
western NV, and some foothill locations receiving up to 10". A few
locations such as I-580/US-395 south of Reno to Washoe Valley, and
parts of the Virginia City Highlands could surpass 1 foot of snow
where enhancement off Lake Tahoe also comes into play. Blowing
and drifting snow with gusty winds of 30-45 mph will also add to
the travel hazards which will affect the PM commute, especially
near and after sunset. For the advisory areas of northwest and
west central NV, snowfall will generally range from 1/2" to 3"
except higher amounts in areas above 5000 feet, with snow finally
reaching Mineral County by late tonight.

The snow will diminish from north to south overnight, with
scattered snow showers lingering through Wednesday mainly south of
US-50. Even though little additional accumulation is expected,
brisk north winds will keep the hazard of blowing snow which could
produce travel hazards on some wind-prone highway segments (such
as I-580 through Washoe Valley) that were previously cleared. As
cloud cover and surface winds diminish Wednesday night,
temperatures will plunge into the single digits and teens with
Sierra valleys dropping below zero, and mountain sites expecting
dangerously cold wind chills between -20 and -40 degrees. MJD

.LONG TERM...THURSDAY-NEXT WEEK...

The weather will quiet down momentarily Thursday and Friday before
the next series of storm systems arrives Saturday through early
next  week. Overall we will see lighter winds, drier conditions,
and high temperatures remaining 10-15 degrees below seasonal
averages during this stretch. Highs through Friday will remain in
the 30s and low 40s across the Sierra and western Nevada
respectively with lows in the teens and 20s.

The pattern will then return to an active phase beginning Saturday
as another upper level low develops off the Pacific Northwest.
This  low will remain nearly stationary while shedding a series
of shortwave troughs across California and Nevada this weekend
into early next week. Winds will begin to increase early Saturday
morning with 100+ mph ridgetop gusts by mid-morning. Winds will
begin to surface down in the valleys during the afternoon with
gusts around 40-50 mph possible mainly north of US-50.

These storms will also maintain a cold character with a period of
moderate to heavy snowfall in the Sierra possible Saturday
afternoon  into Sunday. Spillover snowfall will also be possible
for western Nevada valleys by Sunday morning. This wave is
expected to produce another round of winter weather impacts mainly
across the Sierra where an additional foot or two of snowfall is
possible. Behind this system, additional weaker and colder waves
will push through and provide more snowfall of a showery/scattered
nature. While details in regards to timing and precipitation
amounts with these waves are lower confidence this far out, higher
confidence exists with the development of this large scale
pattern. As such, plan for the potential of additional winter
impacts through much of next week. Fuentes

&&

.AVIATION...

* Widespread significant impacts to aviation will continue through
  early Wednesday morning. Plan on mountain wave turbulence, LLWS,
  periods of IFR conditions or worse, and gusty winds until the
  storm exits early Wednesday.

* Blizzard conditions will continue across Sierra terminals with
  heavy snow and blowing snow leading to near-zero visibility and
  drifting snow. Feet of snowfall are expected through the
  entirety of the storm. SW wind gusts of 30-40 kts will be
  possible this evening before shifting to northwest behind the
  storm by 12z Wed.

* For western NV terminals, mostly off/on snow showers are
  forecast other than a heavier period of snowfall which is
  looking to move across late this afternoon and early evening
  (00-04z). This may yield 1 to 3 inches of snowfall for the
  KRNO/KCXP/KMEV terminals. SW wind gusts of 30-40 kts will be
  possible through this evening before shifting northwest behind
  the storm by 12z Wed. Blowing and drifting snow may lead to
  periodic decreases in visibility.

* Late Wednesday into Friday night will be the first decent break
  from the snow and wind. Another storm is lined up for the weekend
  with more rounds of snow and wind in the forecast. Fuentes/Edan

&&

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

     Blizzard Warning until 4 AM PST Wednesday NVZ002.

     Winter Weather Advisory until 4 AM PST Wednesday NVZ001.

     Winter Storm Warning until 4 AM PST Wednesday NVZ003.

     Winter Weather Advisory until 4 AM PST Wednesday NVZ004.

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

     Winter Storm Warning until 4 AM PST Wednesday CAZ071.

     Blizzard Warning until 4 AM PST Wednesday CAZ072.

     Blizzard Warning until 10 AM PST Wednesday CAZ073.

&&