A cold snap across the area kept much of the valley overnight temperatures below freezing for the first week of December. This was followed by a low pressure system that brought additional cold weather, with very low elevation snow (300-500ft). The snow was significant due to its rarity at the lower elevations, as well as a temporary closures of I-5 in Shasta County and trans-Sierra I-80.

Winter Storm in NORTHEAST FOOTHILLS/SACRAMENTO VALLEY, CALIFORNIA
From 06-DEC-13 14:00:00 to 07-DEC-13 01:00:00 (PST-8)
Reported by: Trained Spotter

The cold, low elevation snow system brought 4 to 12 inches of snow to the foothills. Shingletown received 5-8 inches of snow, and near Brush Creek received 12 inches. Magalia received around 7 inches.

Winter Storm in MT SHASTA/WESTERN PLUMAS COUNTY, CALIFORNIA
From 06-DEC-13 14:00:00 to 07-DEC-13 01:00:00 (PST-8)
Reported by: COOP Observer

The cold, low elevation snow system brought snow to western Plumas and Lassen Park area for several hours. The slopes received approximately 6 to 10 inches of snow, with highest amounts over the Lassen Peak region (18-22). Quincy and Chester received 4-6 inches of snow along the east side of the crest.

Winter Weather in BURNEY BASIN/EASTERN SHASTA COUNTY, CALIFORNIA
From 06-DEC-13 14:00:00 to 07-DEC-13 23:00:00 (PST-8)
Reported by: Trained Spotter

The cold, low elevation snow system only brought around 4 inches to the city of Burney, with locally higher amounts for the higher elevations, as the system spread from northwest to southeast across interior northern California.

Winter Weather in MOUNTAINS SOUTHWEST SHASTA COUNTY TO NORTHERN LAKE COUNTY, CALIFORNIA
From 06-DEC-13 11:00:00 to 06-DEC-13 22:00:00 (PST-8)
Reported by: RAWS

The cold, low elevation snow system only brought around 4 inches for Alder Springs, with less amounts at lower elevations. Some of the higher peaks in northern Lake County were estimated to receive 6-8 inches, but no datasets were found to verify.

Winter Storm in SHASTA LAKE/NORTH SHASTA COUNTY, CALIFORNIA
From 06-DEC-13 11:00:00 to 06-DEC-13 22:00:00 (PST-8)
Reported by: Trained Spotter

A cold storm system spread precipitation across northwest Shasta County for several hours. The low snow levels associated with this system resulted in snow to locations that do not normally receive accumulating snow. There were 3 inches of snow at Shasta Dam, 6-8 inches in the foothills including Sims, and up to 8-12 inches for the higher peak elevations. I-5 was closed for a period of time due to the wintery conditions and multiple car accidents.

Winter Storm in NORTHERN SACRAMENTO VALLEY, CALIFORNIA
From 06-DEC-13 12:00:00 to 06-DEC-13 23:00:00 (PST-8)
Reported by: Trained Spotter

The cold, low elevation snow system brought several inches of snow to the valley floor, which is rare for the area. Areas in Redding and Anderson (400-700ft elevations) received 4-6 inches of snow, with 1-2 inches farther south near Red Bluff and Cottonwood (300-500ft elevations). Locations near Dairyville also received 1-2 inches of snow.  Spotters reported non accumulating snow at elevations as low as 200ft.

Winter Storm in MOTHERLODE/CAMPTONVILLE TO GROVELAND, CALIFORNIA
From 06-DEC-13 16:00:00 to 07-DEC-13 14:00:00 (PST-8)
Reported by: Trained Spotter

The cold, low elevation snow system brought significant amounts to the motherlode foothills, with elevations as low as approximately 800 ft. Auburn (1000 ft elevation) received 1 inch of snow. Grass Valley and Nevada City area received anywhere from 4 to 8 inches, reported by spotters. Higher amounts were reported by spotters near Groveland (12) and Sonora (10). Placerville, Camino, and Somerset areas along and near Highway 50 received 5 to 8 inches. In addition to the snow, the very cold temperatures prompted Nevada and Tuolumne counties to open warming centers in Grass Valley and Sonora, respectively, for several days.

Winter Storm in WEST SLOPE NORTHERN SIERRA NEVADA, CALIFORNIA
From 06-DEC-13 16:00:00 to 07-DEC-13 17:00:00 (PST-8)
Reported by: Trained Spotter

The cold, low elevation snow system dumped significant amounts of snow along the western slopes of the Sierra Nevada. Kirkwood ski resort reported 24-32 inches of snow along their slopes. Other ski resorts such as Sugarbowl and Sierra at Tahoe reported 18-22 inches. Near Donner Pass, areas received 18-22 inches of snow. Kingvale spotter reported 23 inches. Lower elevations such as Sonora (3500-4000ft elevations) reported 12-14 inches, Pacific House (3500ft) reported 11 inches, and Pollock Pines (3900ft) reported 6-8 inches.
In addition, due to multiple spinout accidents on I-80 during the event, Caltrans temporarily closed I-80 eastbound at Applegate (2000ft) and I-80 westbound at the stateline for approximately an hour (early morning on December 7th).