A rare blizzard warning was issued for the Sierra Nevada, including ski resorts at Mammoth Mountain and around Lake Tahoe, as officials urged people to avoid travel during treacherous weather Thursday through Sunday.

Up to 8 feet of snow could fall, the latest forecasts say. The blizzard warning was in effect from Lassen Volcanic National Park in Shasta County to Kings Canyon National Park in Fresno County.

Friday night to Saturday morning is expected to bring the most extreme conditions of severe snowfall and strong winds, with snow falling at a rate of 3 to 5 inches per hour. Wind gusts on the ridge of California's mightiest mountain range are expected to "easily exceed" more than 100 mph, and residents are urged to be prepared for power outages and falling trees.

"There are only so many ways that we can say it will be treacherous to be traveling on the roads or even exiting your home during this time frame," the National Weather Service office in Reno said. "Whiteout conditions are very disorienting, so this is not the time to gamble with you or your family's lives, especially over a planned weekend ski vacation."

The latest forecasts suggest between 4 to 8 feet of snow could fall in the Tahoe Basin at elevations 7,000 feet above sea level, while 2 to 4 feet of snow could fall in the towns around Lake Tahoe. (An earlier forecast said 5 to 12 feet of snow was possible at elevations 5,000 feet above sea level.)

In Mono County, where Mammoth Mountain is located, there could be 3 to 6 feet of snow along the Sierra crest and 1 to 3 feet of snow in the communities along Highway 395, the main route between Mammoth and Southern California. Winds could gust there as high as 70 mph in the lower elevations.

"Do not take this storm lightly. It is shaping up to be the strongest storm of the winter season. Prepare now," the weather service office in Reno said. "If you must travel in the Sierra during this prolonged storm, have a winter kit and plenty of supplies. Nothing like an unsafe, impromptu camping trip in your car on Donner Pass."

Forecasters warned that flights will likely be delayed or canceled, motorists would be ordered to put chains on tires and travelers could get disoriented from whiteout conditions.

Along the two main routes many visitors from the San Francisco Bay Area take to the Lake Tahoe area, the highest point of Interstate 80 — Donner Pass, at an elevation of about 7,000 feet — could get 6 to 8 feet of snow. The tallest point of Highway 50 — Echo Summit — could get 5 to 7 feet of snow.

Officials also warned about traveling on any road above 1,000 feet in northwest California. The National Weather Service office in Eureka warned about heavy snowfall down to elevations of as low as 500 feet, and warned of a "small hail threat" along the coast.

The highest point of Interstate 5 between Redding and the Oregon border — a spot just north of the city of Mount Shasta — could get 6 to 18 inches of snow.

Closer to Southern California, there's a 20% to 30% chance of up to 1 inch of snow along the Interstate 5 over the Tejon Pass, commonly referred to as the Grapevine, which connects L.A. County to the Central Valley.

And there's also a 20% to 30% chance of 1 to 2 inches of snow along Highway 58 over the Tehachapi Pass, the key route between Bakersfield and the Mojave Desert.

The blizzard warning extended to areas of Yosemite National Park outside of Yosemite Valley between Thursday afternoon and Sunday morning. Yosemite Valley — the most popular section of the national park — faces a winter storm warning Saturday morning through Sunday morning. There could be blowing snow in Yosemite Valley on Saturday and heavy snow accumulations.

It's not clear when the Sierra storm will truly be over. The worst snowfall and winds may taper by Sunday, forecasters said, but scattered snow showers could still happen.

"Monday appears to be the best setup for post-storm cleanup and travel for now, but that doesn't appear to be it in terms of the storm potential," the weather service office in Reno said, with the potential for one or two more storms next week.

In Los Angeles and Ventura counties, light to moderate rain was expected to start either Thursday night or Friday, persisting through at least Saturday, the National Weather Service office in Oxnard said. The storm could bring one-quarter to 1 inch of rain along the coast and in the valleys, with 1 to 2 inches in the foothills and mountains.

Snow levels in L.A. County could fall as low as 3,500 feet above sea level on Saturday night into Sunday. In Wrightwood, 4 to 6 inches of snow could fall.

The San Francisco Bay Area was expected to see rain and gusty weather return as early as Thursday, and continue through Saturday, with snow levels falling to 2,000 feet above sea level.

The Sacramento Valley is expected to see strong winds, with gusts of 35 to 50 mph possible from Marysville in Yuba County northward, the weather service office in Sacramento said.

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