Strong low pressure over the northeast Pacific on the 9th moved southeast slowly, reaching northern California on the 12th. This brought exceptional snowfall and a period of blizzard conditions to the Sierra with considerable impacts.

Heavy Snow in MONO, CALIFORNIA
From 09-JAN-17 18:00:00 to 12-JAN-17 16:00:00 (PST-8)
Crop damage: 0.00K
Reported by: COOP Observer

SNOTEL-estimated snowfall totals of 3 to 5 feet fell between the 9th and 12th in the high Sierra and Sweetwater Range, with 4 to 5 inches of water equivalent (SWE) for several SNOTEL sites. At the high end, the Leavitt Lake SNOTEL recorded 10 inches of SWE, with 12 inches at the Mammoth Mountain ski area. Snowfall of 83 inches was measured at the Mammoth Mountain Ski area. Along and east of Highway 395, snowfall totals ranged from 12 to 20 inches.

Heavy Snow in LASSEN/EASTERN PLUMAS/EASTERN SIERRA, CALIFORNIA
From 09-JAN-17 15:00:00 to 12-JAN-17 18:00:00 (PST-8)
Crop damage: 0.00K
Reported by: COOP Observer

The Portola cooperative observer reported 34 inches of snowfall from the 9th through the 12th. A CoCoRAHS site 5 miles west-northwest of Susanville reported 24 inches on the 9th before snow changed to rain (at about midnight on the 10th). Rain or a rain/snow mix changed back to all snow in lower elevations by the evening of the 11th. The Grizzly Ridge HADS at 6900 feet likely received at least 4 or 5 feet of snowfall based on sub-freezing temperatures and precipitation amounts near 8 inches.

High Wind in SURPRISE VALLEY, CALIFORNIA
From 10-JAN-17 11:30:00 to 10-JAN-17 12:30:00 (PST-8)
Magnitude: 52.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: RAWS

Wind gust measured at the Surprise Valley RAWS between 1130PST and 1230PST.

Blizzard in MONO, CALIFORNIA
From 10-JAN-17 13:00:00 to 11-JAN-17 07:00:00 (PST-8)
Crop damage: 0.00K
Reported by: Department of Highways

Highway 395 was shut down through all of Mono County for low visibility/blizzard conditions. Winds were gusting to between 35 and 58 mph in some spots along Highway 395 during the snowfall event, including near Bridgeport and the Mammoth airport.

Heavy Snow in GREATER LAKE TAHOE AREA, CALIFORNIA
From 09-JAN-17 17:00:00 to 12-JAN-17 22:00:00 (PST-8)
Crop damage: 0.00K
Reported by: COOP Observer

Snowfall totals between the 9th and 12th were quite significant. Between the 9th and 12th, 6 to 10 feet of snow fell at ski areas near the Sierra crest, with 3 to 3.5 feet in the Tahoe City and Truckee areas, and 2 to 3 feet in the South Lake Tahoe area. During the evening of the 12th, two trees fell on three cars on CA route 89 near Squaw Valley, resulting in one death. A tree fell into a home in Kings Beach on the 11th, resulting in major damage. Numerous power outages were noted.

Avalanche in GREATER LAKE TAHOE AREA, CALIFORNIA
From 10-JAN-17 10:55:00 to 10-JAN-17 10:55:00 (PST-8)
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Several avalanches were reported in an avalanche-prone area of Alpine Meadows, with 12 to 14 homes affected (minor damage). One controlled avalanche hit at least several houses. A NWS meteorologist who lives in the area noted that a couple homes had damage to their garage doors due to the weight of the snow.

Blizzard in GREATER LAKE TAHOE AREA, CALIFORNIA
From 10-JAN-17 05:00:00 to 11-JAN-17 05:00:00 (PST-8)
Crop damage: 0.00K
Reported by: Department of Highways

All major travel routes through the Tahoe Basin were shut down for more than 24 hours due to poor visibility. Interstate 80 was closed at 2256PST on the 9th due to zero visibility, with the closure lasting through 1300PST on the 11th. With heavy snow and blizzard conditions moving over the rest of the area by early afternoon on the 10th, CA route 267 (Brockway Summit) was closed around 1300PST. Highway 50 was also shut down.