A weather system brought winter weather to the Sierra Nevada and southern Cascades.  Reports of 52 to 66 inches of new snow were received. Low elevation snow also occurred with snow accumulation reported down to approximately 2,500 feet in elevation in the western foothills of the Sierra Nevada. Chain controls were in place on Interstate 80 and Highway 50 during the event. Traffic was also briefly closed to through traffic on I-80 for 34 minutes on the 13th due to downed powerlines. A rock slide also closed state route 70 at 3:30 am on the 13th. Highway 49 was closed during the event due to a down tree. Power outages were also reported across the region. Several counties also opened warming centers for the cold temperatures.

High Wind in MT SHASTA/WESTERN PLUMAS COUNTY, CALIFORNIA
From 13-DEC-21 04:00:00 to 13-DEC-21 22:00:00 (PST-8)
Magnitude: 39.00 MG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Law enforcement reported that winds caused downed trees and power lines, which led to blocked lanes on roadways and hazardous driving conditions. Peak wind gusts for the zone reached from 35 to 45 mph.

High Wind in SHASTA LAKE/NORTH SHASTA COUNTY, CALIFORNIA
From 13-DEC-21 04:00:00 to 13-DEC-21 23:59:00 (PST-8)
Magnitude: 36.00 MG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Law enforcement reported that winds caused a downed power line. Peak wind gusts for the zone reached around 42 mph. Damage costs are estimated.

High Wind in MOTHERLODE/CAMPTONVILLE TO GROVELAND, CALIFORNIA
From 13-DEC-21 04:00:00 to 13-DEC-21 23:59:00 (PST-8)
Magnitude: 50.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Law enforcement reported that winds caused downed trees and power lines, which led to closed roadways, hazardous driving conditions and power outages. Peak wind gusts for the zone reached from 46 to 58 mph. Damage costs are estimated.

High Wind in CENTRAL SACRAMENTO VALLEY, CALIFORNIA
From 13-DEC-21 04:00:00 to 13-DEC-21 23:59:00 (PST-8)
Magnitude: 50.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Law enforcement reported that winds caused downed trees and power lines, which led to closed roadways, hazardous driving conditions and power outages. Peak wind gusts for the zone reached from 46 to 58 mph. Damage costs are estimated.

High Wind in SOUTHERN SACRAMENTO VALLEY, CALIFORNIA
From 13-DEC-21 04:00:00 to 13-DEC-21 22:00:00 (PST-8)
Magnitude: 49.00 MG
Property damage: 3.00K
Crop damage: 0.00K
Reported by: ASOS

High winds caused a significant amount of trees and powerlines to fall across the area causing widespread power outages leading to tens of thousands of people left without power, roadways were closed and blocked, and dangerous driving conditions were observed including a vehicle struck by a powerline. Peak wind gusts reported for the zone reached 47 to 56 mph. Damage costs are estimated.

High Wind in WEST SLOPE NORTHERN SIERRA NEVADA, CALIFORNIA
From 13-DEC-21 04:00:00 to 13-DEC-21 23:59:00 (PST-8)
Magnitude: 121.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

There were multiple reports of power outages across the Sierra high country after heavy snow and winds. Gusts across the high Sierra reached 112 to 139 mph. Interstate 80 was closed to traffic in both directions for a period of time due to down powerlines. Damage costs are estimated.

High Wind in CENTRAL SACRAMENTO VALLEY, CALIFORNIA
From 13-DEC-21 04:00:00 to 13-DEC-21 23:59:00 (PST-8)
Magnitude: 44.00 MG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Law enforcement reported that winds caused a broken power poll in the zone. Peak wind gusts in the zone reached 49 to 51 mph. Damage costs are estimated.

High Wind in NORTHERN SACRAMENTO VALLEY, CALIFORNIA
From 13-DEC-21 04:00:00 to 13-DEC-21 23:59:00 (PST-8)
Magnitude: 56.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Peak wind gusts for the zone reached 62 to 65 mph.

High Wind in NORTHEAST FOOTHILLS/SACRAMENTO VALLEY, CALIFORNIA
From 13-DEC-21 04:00:00 to 13-DEC-21 23:59:00 (PST-8)
Magnitude: 63.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Peak wind gusts for the zone reached 65 to 72 mph.

Winter Storm in MOTHERLODE/CAMPTONVILLE TO GROVELAND, CALIFORNIA
From 11-DEC-21 16:00:00 to 14-DEC-21 04:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

CoCoRaHS observers reported low elevation snow across the Motherlode during the storm.  6.6 miles ESE of Placerville at an elevation of 2587 feet saw 6 inch.
1.3 miles NNE of Grass Valley at an elevation of 2782 feet saw 5 inches.
1.7 miles SSE of Nevada City at an elevation of 3168 feet saw 2.0 inches.
3.93 miles E of Nevada City at an elevation of 3196 feet saw 4 inches.
1.6 miles SW of Twain Harte at an elevation of 3231 feet saw 7.5 inches.
1.6 miles SW of Tuolumne at an elevation of 2706 feet saw 0.5 of an inch.
1.2 miles N of Camino at an elevation of 3091 feet saw 8 inches.
River Pines at an elevation of 2033 feet saw 2.0 inches.
2 miles N of Tuolumne City at an elevation of 2915 feet saw 4 inches.
2.1 miles SW of Tuolumne at an elevation of 2706 feet saw 5 inches.
2.7 miles NNW of Pioneer at an elevation of 3412 feet saw 8.5 inches.
1.3 miles WSW of Challenge-Brownsville at an elevation of 2049 feet saw 2.5 inches.

High Wind in NORTHERN SAN JOAQUIN VALLEY, CALIFORNIA
From 13-DEC-21 04:00:00 to 13-DEC-21 23:59:00 (PST-8)
Magnitude: 52.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Law enforcement reported that winds caused downed trees which led to hazardous driving conditions across the zone. Peak wind gusts in the zone reached 52 to 60 mph.

Winter Storm in MOTHERLODE/CAMPTONVILLE TO GROVELAND, CALIFORNIA
From 11-DEC-21 16:00:00 to 14-DEC-21 04:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Law enforcement reported debris on roadway in the zone. Some large boulders as well as rocks and dirt led to blocked lanes on roadways and hazardous driving conditions.

Winter Storm in WEST SLOPE NORTHERN SIERRA NEVADA, CALIFORNIA
From 11-DEC-21 16:00:00 to 14-DEC-21 04:00:00 (PST-8)
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Department of Highways

Caltrans reported approximately 4.75 feet of new snow at their Kingvale location. Traffic was also briefly closed to through traffic on I-80 for 34 minutes on the 13th due to downed powerlines.

Winter Storm in NORTHEAST FOOTHILLS/SACRAMENTO VALLEY, CALIFORNIA
From 11-DEC-21 16:00:00 to 14-DEC-21 04:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

CoCoRaHS observers reported low elevation snow in Shingletown during the storm. 2.5 miles E of Shingletown at an elevation of 3643 feet saw 0.2 of an inch. 3.5 miles E of Shingletown at an elevation of 3643 feet saw 8.3 inches.

Flood in SACRAMENTO, CALIFORNIA
From 13-DEC-21 09:04:00 to 13-DEC-21 20:45:00 (PST-8)
Location: SACRAMENTO
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

Heavy rain and flooding was reported in Sacramento. Law enforcement reported numerous flooded off ramps and roads that lead to roadway closures  and car accidents.  Reported storm totals reached 2.6 to around 4 inches of rain.

Heavy Rain in NEVADA, CALIFORNIA
From 13-DEC-21 18:24:00 to 13-DEC-21 20:00:00 (PST-8)
Location: FRENCH CORRAL
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Two boulders blocked state route 49 near Nevada City, CA reported by CHP. Reported storm total rainfall amounts in the area were in excess of 3 inches.

Flood in SOLANO, CALIFORNIA
From 13-DEC-21 10:58:00 to 13-DEC-21 12:00:00 (PST-8)
Location: VACAVILLE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Lane flooded on I-80E at Alamo Dr. offramp. Reported storm total rainfall amounts in the area were in excess of 3 inches.

Flood in SUTTER, CALIFORNIA
From 13-DEC-21 15:45:00 to 13-DEC-21 17:00:00 (PST-8)
Location: EAST NICOLAUS
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

California highway patrol reported roadway flooding at the intersection of highway 70 E. Reported storm total rainfall amounts in the area were in excess of 3 inches.

Winter Storm in MT SHASTA/WESTERN PLUMAS COUNTY, CALIFORNIA
From 11-DEC-21 16:00:00 to 14-DEC-21 04:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Chester reported 17.5 inches of storm total snow.

Winter Storm in MT SHASTA/WESTERN PLUMAS COUNTY, CALIFORNIA
From 11-DEC-21 16:00:00 to 14-DEC-21 04:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Quincy reported 13 inches of snow.

Flood in SUTTER, CALIFORNIA
From 13-DEC-21 21:39:00 to 13-DEC-21 23:00:00 (PST-8)
Location: BERG
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Flooded lanes at Tierra Buena Rd. Reported storm total rainfall amounts in the area were in excess of 2.5 inches.

Heavy Rain in BUTTE, CALIFORNIA
From 13-DEC-21 20:03:00 to 13-DEC-21 22:03:00 (PST-8)
Location: CHICO RANCHAERO ARPT
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Road closed due to flooding at the intersection of W Sacramento Ave and Meridian Rd. reported by CHP. Reported storm total rainfall amounts in the area were in excess of 3 inches.

Winter Storm in WEST SLOPE NORTHERN SIERRA NEVADA, CALIFORNIA
From 11-DEC-21 16:00:00 to 14-DEC-21 04:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Sierra Nevada Ski Resorts reported between 36 and 66 inches of snow accumulation for the entire event. Kirkwood reported 61 inches, Dodge Ridge reported 66 inches, Sugar Bowl 52 inches, Boreal 54 inches, and Bear Valley got 57 inches of total snow.