SIERRA NEVADA, Calif. (KRON) – An Atmospheric River is expected to bring 5 to 8 feet of snow to parts of the Sierra, Nevada by Friday.

The National Weather Service upgraded a Winter Storm Warning to a Blizzard Warning, and authorities are warning people to avoid all non-essential travel to the Sierra.

Both I-80 and US-50 should be avoided, according to officials.

On Tuesday evening, the National Weather Service Reno announced that a Backcountry Avalanche Warning was issued for Central Sierra Nevada Mountains.

‘Extreme danger’ in the area is expected from Wednesday through Friday morning.

Snow was falling right here in the Bay Area on Tuesday night.

Cal Fire tweeted out a video showing the snow falling at higher elevations in the Santa Cruz Mountains.