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.

Heavy Snow in LASSEN/EASTERN PLUMAS/EASTERN SIERRA, CALIFORNIA
From 22-DEC-21 08:00:00 to 23-DEC-21 15:30:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter located 6.0 mi SSE of Susanville, CA in Lassen County reported  3.5��� of wet snow at an elevation of 4800���.

Winter Storm in GREATER LAKE TAHOE AREA, CALIFORNIA
From 25-DEC-21 12:00:00 to 26-DEC-21 12:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

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).

High Wind in MONO, CALIFORNIA
From 23-DEC-21 07:00:00 to 23-DEC-21 08:00:00 (PST-8)
Magnitude: 92.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Mesonet station (MTH03) located 1.7 mi S of Mammoth Mountain Ski summit reported a wind gust of 106 mph.

Heavy Rain in MONO, CALIFORNIA
From 22-DEC-21 08:00:00 to 23-DEC-21 08:00:00 (PST-8)
Location: MONO LAKE
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

CO-OP Observer, COCORAHS station (CA-MN-6), and mesonet sites reported heavy rain ranging from 0.55���-0.65��� in Lee Vining and up to 2.00��� at mesonet site (CRVC 1) 1.0 mi SSW of Crestview, CA.

Heavy Rain in MONO, CALIFORNIA
From 23-DEC-21 08:00:00 to 24-DEC-21 08:00:00 (PST-8)
Location: BRIDGEPORT
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

COCORAHS station (CA-MN-5),  AWOS, and mesonet sites reported heavy rain ranging from 0.72��� at Benton, CA (BETC1),  to 1.16��� from AWOS located  at USMC  MWTC Bridgeport, and 2.47��� at the  mesonet site (CRVC1) located 1.0 mi SSW of Crestview, CA.

Heavy Snow in MONO, CALIFORNIA
From 23-DEC-21 08:00:00 to 24-DEC-21 08:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

The public reported 24hr heavy snowfall amounts ranging 31���-40��� at Mammoth Mountain Ski Base.

Heavy Snow in MONO, CALIFORNIA
From 24-DEC-21 08:00:00 to 25-DEC-21 08:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

The public reported 24hr heavy snowfall amounts of 10��� at Mammoth Mountain Ski Base and June Mountain Ski Base.

High Wind in MONO, CALIFORNIA
From 25-DEC-21 05:56:00 to 26-DEC-21 06:30:00 (PST-8)
Magnitude: 85.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Mesonet station (MTH03) located 1.7 mi S of Mammoth Mountain Ski summit and Mesonet station (SE089) located 1.3 mi SW of Conway Summit both reported a wind gusts of 98 mph.

Heavy Snow in MONO, CALIFORNIA
From 26-DEC-21 08:00:00 to 27-DEC-21 08:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

The public reported 24hr heavy snowfall amounts 14��� at Mammoth Mountain Ski Base and 22��� at June Mountain Ski Base.

Heavy Snow in MONO, CALIFORNIA
From 21-DEC-21 08:00:00 to 28-DEC-21 08:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

The public reported a 7 day storm total snow amount of 83��� at Mammoth Mountain Ski Base and 78��� at June Mountain Ski Base.

Heavy Snow in GREATER LAKE TAHOE AREA, CALIFORNIA
From 21-DEC-21 08:00:00 to 28-DEC-21 08:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

The public reported a 7 day storm total snow amount of 78��� at Heavenly Ski Base.

High Wind in LASSEN/EASTERN PLUMAS/EASTERN SIERRA, CALIFORNIA
From 25-DEC-21 04:00:00 to 26-DEC-21 05:00:00 (PST-8)
Magnitude: 57.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Mesonet station (TADC1) located 4.0 mi WNW of Truckee, CA reported wind gust of 66 mph.

Heavy Snow in GREATER LAKE TAHOE AREA, CALIFORNIA
From 21-DEC-21 08:00:00 to 28-DEC-21 08:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

The public reported a 7 day storm total snow amount of 132��� 1.0 mi SSW of the Northstar Ski Base.

Heavy Snow in LASSEN/EASTERN PLUMAS/EASTERN SIERRA, CALIFORNIA
From 25-DEC-21 08:00:00 to 26-DEC-21 08:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter located 5.0 mi WNW of Susanville, CA reported 24hr heavy snowfall amount of 25��� with current snow depth of 37���.

Heavy Rain in SIERRA, CALIFORNIA
From 22-DEC-21 17:00:00 to 23-DEC-21 17:00:00 (PST-8)
Location: PEAVINE
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

CO-OP Observer station (VERC1) located 2.0 mi W of Verdi, NV (or 2.0 mi SSE of Dog Valley, CA) reported heavy rain amount of 2.07���.

Heavy Rain in PLUMAS, CALIFORNIA
From 23-DEC-21 15:00:00 to 24-DEC-21 15:00:00 (PST-8)
Location: CROMBERG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Mesonet stations located 3.0 mi SSE of Frenchman Lake and 5.0 mi NNE of Cromberg reported heavy rain amounts of 1.24��� and 1.74��� respectively.

Heavy Rain in EL DORADO, CALIFORNIA
From 23-DEC-21 07:00:00 to 24-DEC-21 07:00:00 (PST-8)
Location: MEYERS
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

COCORAHS station (CA-ED-20) located 4.9 mi SW of South Lake Tahoe, CA (or 2.0 mi NW Meyers, CA) reported heavy rain amount of 1.8���.

Heavy Rain in NEVADA, CALIFORNIA
From 23-DEC-21 07:00:00 to 24-DEC-21 07:00:00 (PST-8)
Location: (TRK)TRUCKEE/TAHOE A
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

COCORAHS Station (CA-NV-51) located 1.6 mi N of Truckee, CA reported heavy rain amount of 2.45���.

Heavy Rain in EL DORADO, CALIFORNIA
From 22-DEC-21 08:00:00 to 23-DEC-21 08:00:00 (PST-8)
Location: MEYERS
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Mesonet stations located at various locations around Meyers, CA reported heavy rain amounts ranging 2.0��� to 3.0��� from Fallen Leaf Lake to Lake Baron, CA.

Heavy Snow in GREATER LAKE TAHOE AREA, CALIFORNIA
From 22-DEC-21 07:00:00 to 27-DEC-21 09:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

According to the U.C. Berkeley Central Sierra Snow Lab, Lake Tahoe has seen a record-breaking amount of snow in December - 214 inches.  The Sierra Snow Lab reported that the Dec 2021 snowfall was the third snowiest on record per tracking from the lab that started in 1970.