A fierce arctic storm pounded California on Friday, threatening to soak mudslide-prone canyons already charred by wildfires and to paralyze the mountains with deep snow.

Power already was knocked out to hundreds of thousands of residents, and the California Highway Patrol encouraged drivers to stay off the roads. Truckers were told to hunker down in blizzard-like conditions over mountain passes in the Sierra Nevada, and even some ski resorts closed.

''It's a whiteout here,'' said Neil Erasmus, general manager of Ice Lake Lodge and Rainbow Lodge in Soda Springs. ''We're plowing and grooming, plowing and grooming to keep us from being buried in.''

Forecasters said the mountains could see 10 feet of snow total from the trio of storms that was expected through the weekend. The sprawling, swirling system spanned the length of the West Coast.

Winds howled in the mountain areas, gusting up to 85 miles an hour, and in the Sacramento Valley, gusts topped 65 mph, the strongest in a decade.

Parts of highways from Sacramento to San Francisco were closed because debris blocked lanes. Ferry service in the San Francisco Bay was interrupted, as well.

''It isn't the weather that causes these collisions, it's the way people drive in them,'' said Sgt. Les Bishop, a spokesman for California Highway Patrol. ''It's no secret that we've got a major storm rolling in, and it's everybody's responsibility to drive in a safe manner.''

Hundreds of thousands of residents lost power across Northern California, from the Bay Area to the Central Valley.

''Because of the strong winds and heavy rains, restoration is taking longer than normal,'' said Darlene Chiu, a spokeswoman for Pacific Gas and Electric.

Homeowners rushed to stack sandbags around houses, and scurried to stock up on last-minute provisions.

''People were waiting in line for shopping carts,'' said Barbara Sholle, of Mammoth Lakes. Sholle went to the supermarket after receiving a call from the eastern Sierra ski town's reverse-911 system. She waited an hour to pay for her groceries amid a crush of residents.

In Southern California, the storm was gathering strength off the coast and was expected to strike the region by mid-afternoon, National Weather Service forecaster Andrew Rorke said.

''We're watching it really blossom on satellite,'' he said.

The storm was expected to pour up to 4 inches of rain overnight in Southern California's valleys, with 6 inches possible in the foothills of the San Gabriel Mountains and up to 12 inches in the south-facing mountains from Ventura County south to San Diego.

''The last rain we had, it all went under my foundation and I don't like that. It was flowing under my house,'' said Cindy Darling, a receptionist at the Lake Arrowhead Chamber of Commerce who got sandbags from the local fire department to put above her house. ''Everything up here's on a hill, so you have to do something.''

Authorities in Orange County issued a voluntary evacuation order for residents of fire-scarred Modjeska and Silverado canyons beginning Friday afternoon. The order also calls for the mandatory evacuation of large animals from the mudslide-prone canyons, where 15 homes burned last fall in a 28,000-acre wildfire.

Ocean tides were expected to swell to 30 feet, prompting the U.S. Coast Guard to caution boaters to remain in port.

No planes were taking off or landing at Sacramento International Airport because of high winds, but the airport remained open, said spokeswoman Gina Swankie.

The state opened its emergency operations center Friday morning to coordinate storm response.

Riverside and San Bernardino counties have deployed swift-water rescue teams in case torrential rains bring flash floods and mudslides.

Several ski resorts weren't taking any chances, with Heavenly Mountain Resort at South Lake Tahoe, Alpine Meadows Ski Area in Tahoe City, Mt. Rose Ski Resort near Reno and Badger Pass Ski Area in Yosemite National Park shutting down for the day.

''It's just really, really windy and we don't feel it's safe conditions for our operators or the public,'' Alpine Meadows spokeswoman Laura Ryan said.

Snow began falling in Tuolumne Meadows Thursday night, and a steady rain was pelting the Yosemite Valley by Friday morning, Yosemite National Park spokesman Scott Gediman said.

Residents and local officials from Sacramento to Manteca planned to patrol the Sacramento-San Joaquin Delta during high tide midday Friday to watch for levee breaks, but weren't predicting major floods, said Ron Baldwin, director of emergency operations for San Joaquin County.

''We're going to have to keep an eye on the water and the high tides but we're hopeful we can get through this without any problems,'' Baldwin said. ''That said, no one's going home.''

As the storms barreled into the West, a freeze in the East was subsiding. Florida's citrus growers might have been spared major damage, but it will be Saturday or later before strawberry farmers know the extent of their losses.

A serious freeze would have been devastating to the Florida's citrus trees, already struggling from years of diseases and hurricanes. But most groves are in central and South Florida, where temperatures hovered in high 20s and low 30s. Trees can be ruined when temperatures fall to 28 degrees for four hours.

''It could have been far, far worse,'' said Terry McElroy, a spokesman for the state Department of Agriculture and Consumer Services.

At Bill Baggs Cape Florida state park in Key Biscayne, iguanas were falling out of trees Thursday. The cold-blooded reptiles go into a sort of hibernation when temperatures get too low, even if they are perched in branches. Most woke up when the weather warmed later in the day.

The animals are not native to Florida and are considered a nuisance, park officials told The Miami Herald.


Associated Press Writer Gillian Flaccus in Orange County, Calif., Juliana Barbassa in San Francisco, Scott Sonner and Sandra Chereb in Reno, Nev., Anthony McCartney in Tampa, Fla., and Don Thompson in Sacramento contributed to this report.