A series of eastern Pacific winter storm pulses, occasionally aided by induction of warmer sub-tropical moisture, caused a variety of hazardous winter conditions that disrupted holiday travel and commerce over the Sierra and western NV.
Every event with a place to put it; 13 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS REV wrote it up.
A series of eastern Pacific winter storm pulses, occasionally aided by induction of warmer sub-tropical moisture, caused a variety of hazardous winter conditions that disrupted holiday travel and commerce over the Sierra and western NV.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Reno, NV wrote its last area forecast discussion before the first event at Dec 21, 3:13 PM PST, 8 hours 47 minutes earlier.
Area Forecast Discussion
National Weather Service Reno NV
313 PM PST Tue Dec 21 2021
...MAJOR TRAVEL DISRUPTIONS THROUGH THE HOLIDAY WEEKEND...
.SYNOPSIS...
Stormy weather returns tonight with rain and snow, mainly for the
Sierra and northeast California. Be prepared for major travel
disruptions and delays in the Sierra, especially by Thursday.
Snow will continue in the Sierra through most of the holiday
weekend with chances for accumulating snow down into western
Nevada valleys by Christmas Day.
&&
.SHORT TERM...
The main message remains the same, "Travel across the Sierra will
be difficult to impossible at times through the holiday weekend".
What has changed with this first system is a slower infiltration
of cold air and precipitation as the initial trough elongates as
it moves into northern California with a split evident at 500 mb.
Snow levels may start low as precipitation moves in with cold air
still trapped in many valleys. However, tonight into tomorrow,
slightly more southerly flow may push snow levels as high as
7000-7500 feet.
Snow is forecast to move into NE California around 7-9 pm, and may
not begin to impact Donner Summit/Carson Pass until around 2 or 3
AM. With this slower onset we have pushed back the onset of the
initial Winter Weather Advisory.
For this first system tonight through Wednesday night, rising
snow levels may only bring light snow to the lower elevations of
NE California and the Tahoe Basin with just a few inches or less
of accumulation with lower level accumulations more likely tonight
during the precipitation onset. Above about 7000' we should still
see around foot or so of new snow. Snow levels are currently
expected to peak Wednesday afternoon, descending with a slow
lowering process Wednesday night.
In western Nevada, expect breezy winds tomorrow with rain showers
becoming increasingly likely Wednesday afternoon through Thursday
as the storm moves inland. -Zach
.LONG TERM...Thursday night through the first week of 2022...
* FORECAST CHANGES -- Colder air arrival has been delayed 18-24
hours with snow levels not near lower valley floors until Friday
or Friday night.
* Unsettled conditions will impact much of the West through the
holiday weekend. Check your flight status routinely and keep an
eye on road conditions by checking with CALTRANS and NDOT.
* Periods of most concern in long term -- Thursday night (mainly
Sierra), Christmas or Christmas Night (Sat-Sat night), then
possibly Monday. Potential for heavier snowfall may produce the
most impactful and hazardous travel conditions.
* SIERRA and NORTHEAST CA PASSES -- Major travel impacts with very
long travel times and possibly periodic road closures. While
snowfall rates may lessen Friday, snow-covered roads will likely
continue to create travel issues. Heavier snow returns over the
weekend.
* WRN NV VALLEYS and FOOTHILLS -- Largest shift in forecast
thinking. Rain or a rain/snow mix (above 5500-6500 feet) with
minimal impact through Thursday. Snow levels drop on Friday or
Friday night (Christmas Eve) with increasing potential for
travel disruption due to snow for the Christmas weekend.
Overview:
Anomalous ridge parked over the Bering Sea and Gulf of Alaska will
keep a large-scale trough anchored near the West Coast through the
next 7 days and likely into early 2022. This setup will facilitate
rounds of cold, continental air diving southward into the West. This
will also allow some subtropical moisture to slide under the ridge
into the West Coast through the holiday weekend.
* THURSDAY NIGHT THROUGH FRIDAY NIGHT (CHRISTMAS EVE) *
- With a major model shift in the past day, warmer southwest flow
aloft looks to dominate for up to another whole day, with enough
colder air finally filtering in Friday and Friday night to
drive snow levels to lower valley floors. Snow level still are
expected to remain low enough to affect all Sierra and
northeast California passes; however, it could delay meaningful
snow accumulations between 5500-6500 feet in the Sierra until
later Thursday evening. The Sierra and mountain communities
look to transition to light to occasionally moderate snow
showers on Christmas Eve as upper forcing temporarily wanes.
However, western Nevada valleys may have to be patient for
notable snowfall accumulations until the weekend with the next,
colder disturbance.
* CHRISTMAS WEEKEND *
- Another round of snow will be possible for the weekend as a
colder shortwave drops into CA and NV. That wave is aligned
very well in simulations, giving confidence in another
round of snow in the Sierra on Christmas along with
increased chances for western NV valleys. The Sierra could
pick up another 1-3 feet of snowfall. For western NV, it's
too early to comment on exact amounts (very sensitive to
location of forcing for sustained snow) but we can say that
travel disruptions are becoming increasingly likely even
'down here'.
* NEXT WEEK INTO THE FIRST WEEK OF 2022 *
- Another wave with snowfall at all elevations is possible
around next Monday as cold systems continue to drop down
from the north. Of particular note will be a moderate chance
for below to well below average temperatures into 2022 with
the cold continental flow filtering in and being reinforced
periodically behind disturbances. In areas with more than a
couple inches of snowfall on the ground, very cold lows
(below zero if there are clear skies and calm conditions)
with highs below freezing will be possible down to the lower
valleys. -Snyder
&&
.AVIATION...
LLWS and moderate turbulence due to mountain waves for all
terminals will persist through the afternoon and into the evening.
Tonight, a series of systems will approach the area, bringing rounds
of heavy mountain snow. Visibilities will be diminished greatly with
mountain obscuration likely and periods of LIFR/IFR for KTRK and
KTVL around 06Z and through the night. For the valleys and terminals
such as KRNO, KCXP, and KMEV, light to moderate precipitation could
be in the form of rain/snow transitions at times.
Flight conditions will include icing issues and wind gusts that will
create moderate to severe turbulence and LLWS. Late Friday, snow
levels will drop to valley floors, bringing increased chances of
snow to all terminals.
HRICH
&&
.REV Watches/Warnings/Advisories...
NV...Winter Weather Advisory from 2 AM Wednesday to 4 AM PST Thursday
NVZ002.
Winter Storm Warning from 4 AM Thursday to 4 PM PST Sunday
NVZ002.
CA...Winter Weather Advisory from 10 PM this evening to 4 AM PST
Thursday above 5000 feet in CAZ071.
Winter Storm Warning from 4 AM Thursday to 4 PM PST Sunday
CAZ071.
Winter Storm Warning from 4 PM Wednesday to 4 PM PST Sunday
CAZ073.
Winter Weather Advisory from 2 AM Wednesday to 4 AM PST Thursday
CAZ072.
Winter Storm Warning from 4 AM Thursday to 4 PM PST Sunday
CAZ072.
&&
For more information from the National Weather Service visit...
http://weather.gov/renoThe national radar mosaic for the moment the first event began.
6 heavy snow, 4 winter storm, 3 high wind, 2 flood, 1 heavy rain. Local standard time, as filed.
Trained spotter and the public reported an estimated accumulation of 0.01 of freezing precipitation 3.0 mi E of Verdi, greater areas of the city of Reno, and 1.0 E of Spanish Springs in Washoe County.
COCORAHS station (nv-ly-15) 3.4 mi NE of Dayton,NV reported 1.52 of heavy rain.
Road Closed (Road Hazard) - on US-6 in both directions between SR-360/Mina-Basalt Cutoff Rd and the California State-line in Mineral County Nevada.
Trained spotters and the public reported heavy snowfall amounts up to 19 1.0 mi NNW of Incline Village as well as 22 at the MT. Rose Ski Base.
Trained weather spotter reported minor flooding along Pyramid Highway and Eagle Canyon Dr.
NDOT closed I-80 and Rock Blvd underpass due to minor flooding.
NDOT road crew personnel reported heavy snow that fell between 10AM to 11PM with storm total snow estimated between 1'-2' along US Highway 6 to Montgomery Pass in Mineral County.
The Reno 88D radar on Virginia Peak had been without commercial power for roughly 4 days. A visit to the site by electronics staff via snowcat on Christmas Day accessed there was ample generator fuel for about 5 additional days. WFO Reno continued to work with NV Energy on getting commercial service restored, including reaching out to their emergency manager.
Trained weather spotter reported a 24 hr snowfall total of 8 of new 3.0 mi WSW of Gardnerville Ranch, NV.
Official NWS OBS reported 24hr heavy snowfall amounts of 9 at the NWS Reno Office while the public reported 24hr heavy snowfall amounts of 23 at the MT. Rose Ski Base and 32 at the Diamond Peak Ski Base.
The following information was included in High Impact Event report issued 12/26/2021 and 12/27/2021.
Interstate-80 was closed through at least mid-day Monday when the conditions were re-evaluated. Based on the heavy snow forecast Interstate remained closed until Tuesday with no specific estimated opening time. Virtually all trans-Sierra routes are closed due to snow and/or wind impacts - this is also unusual to have so many routes disrupted this long. Caltrans received email briefings from both WFO Reno and WFO Sacramento.
Southwest Airlines, the largest carrier in Reno, had cancelled all flights today and tonight (12/26/2021), due to wind concerns. Coordination with Reno Airport operations on snow and wind trends.
Accident involving 20-cars on Interstate 580 between Reno and Carson City with at least 6 injuries requiring hospitalization. Blowing slow occurring at the time of accident.
Highway 395 in the Eastern Sierra closed for prolonged periods, due to measured wind gusts near the highway of 85 to 98 mph, blowing snow, and low visibility. This is a major route between LA, Mammoth, and Reno.
All ski areas in the Tahoe region were closed due to dangerous conditions and high winds. Massive impacts likely to people on holiday who may now be stranded at these resorts possibly into Monday and Tuesday.
Several avalanche reports in the Eastern Sierra but no damage or injuries reported. One occurred near Alpine Meadows closing the only road in and out of the ski area.|An avalanche occurred in the Tahoe area, closing CA 89 which is the main route from Tahoe to I-80. This along with the continued hazardous snowfall and winds, had resulted in the closure of all ski areas in the Tahoe-Truckee region through Monday (12/27/2021).
Mesonet station (NV021) 2.0 mi SW of Gardnerville(NV DOT) reported wind gust of 65 mph.
Mesonet station (WLKNV) 6.1 mi NW of Hawthorne (NV DOT) reported wind gust of 61 mph.
The public reported 24hr heavy snowfall amounts of 18 at the Diamond Peak Ski Base and 30 at the MT. Rose Ski Base.
Mesonet station (WASNV) 3.2 mi S of Washoe City(NV DOT) reported wind gust of 66 mph.
Local newspaper reported via social media that Genoa, NV received 9.5 of new snow.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Nevada in 2021Every state in 2021This day in weather historyWarnings in Nevada, December 2021
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 992647, 992684, 991416, 992688, 992670, 992671, 992660, 992668, 992677, 992691, 992664, 992673, 992672, 992692, 992675, 992680.