RENO, Nev. >> A winter storm packing powerful winds, heavy rain and potentially several feet of snow in the Sierra Nevada shut down mountain highways, toppled trees and triggered flood watches and avalanche warnings today from the coast of Northern California to Lake Tahoe.

More than 250 miles of the Sierra remained under a winter storm warning at least until Sunday night or early Monday from north of Reno to south of Yosemite National Park.

As much as 4 feet of snow is expected to fall by the end of the weekend in the upper elevations around Lake Tahoe, and as much as 6 feet in more remote parts of the Sierra to the north and south.

A 70-mile stretch of eastbound U.S. Interstate 80 was closed “due to zero visibility” from Colfax, California, to the Nevada state line, transportation officials said. Chains were required on much of the rest of I-80 in the mountains from Reno toward Sacramento.

A stretch of California Highway 89 also was closed due to heavy snow between Tahoe City and South Lake Tahoe, California, the highway patrol said.

The U.S. Forest Service issued an avalanche warning for the backcountry in the mountains west of Lake Tahoe where it said “several feet of new snow and strong winds will result in dangerous avalanche conditions.”

Gusts of wind up to 50 mph that sent trees into homes in Sonoma County on Saturday could reach 100 mph over Sierra ridgetops by early Sunday, the National Weather Service said.

Heavy rain was forecast through the weekend from San Francisco to the Sierra crest with up to 2 inches in the Bay Area and up to 5 inches at Grass Valley northeast of Sacramento.

The weather service issued a flash flood warning today when inches of rain fell on burn scars left by wildfires south of Monterey and farther south of Big Sur.

More than 30,000 customers were without power in the Sacramento area at one point Saturday morning, but it was restored to all but a few hundred late in the day. The drivers and passengers of five cars that had been trapped between downed power lines escaped unharmed, the Sacramento Bee reported.

San Francisco Bay Area officials reported power outages and fallen trees, some of which damaged cars and homes. In Monte Rio, a small town along the Russian River in Sonoma County, firefighters responded to several reports of downed trees crashing into homes in 50 mph wind gusts.

Monte Rio Fire Department Chief Steve Baxman told KRON-TV that four different down trees had damaged houses in the area and that no injuries were reported.

“This is our first big storm, we’ve had several years of drought and all these trees were dry. Now they’re filling up with water and starting to topple over,” Baxman told the television station.

In the Sierra, about 10 inches of snow already had fallen Saturday afternoon at Mammoth Mountain ski resort south of Yosemite where more than 10 feet of snow has been recorded since early November.

“It just seems like every week or so, another major storm rolls in,” resort spokeswoman Lauren Burke said.

As much as 18 to 28 inches of snow was forecast through the weekend at lake level, and up to 4 feet at elevations above 7,000 feet with 50 mph winds and gusts up to 100 mph.

On the Sierra’s eastern slope, a winter weather advisory runs from 10 p.m. Saturday to 10 a.m. for Reno, Sparks and Carson City, with snow accumulations of 1 to 3 inches on valley floors and up to 8 inches above 5,000 feet.