OMAHA, Neb. – Severe weather hit parts of the United States during the first half of the weekend, with dangerous conditions including heavy snow in New York state, a severe ice storm in Midwestern states, severe weather warnings around Lake Tahoe and unusual tornado activity in central California.

The ice storm, which began Friday evening, created treacherous driving conditions across Iowa and eastern Nebraska Friday through Saturday and led to temporary closures of Interstate 80 after numerous cars and trucks were driven off the road. In New York state, more than 33 inches (84 centimeters) were reported near Orchard Park, which is often a landing point for lake-effect snow.

On Saturday, a tornado touched down near a shopping center in Scotts Valley, California, about 70 miles (110 kilometers) south of San Francisco, around 1:40 p.m. The tornado overturned cars and toppled trees and utility poles, the National Weather Service said. Scotts Valley police said several people were injured and taken to hospitals.

In San Francisco, some trees fell on cars and streets and damaged roofs. The damage was being assessed to determine whether the city was actually hit by a tornado, which the weather service said had not occurred since 2005.

Roger Gass, a meteorologist at the weather service’s office in Monterey, California, said the warning of a possible tornado in San Francisco was a first for the city, noting that an advance warning was not issued until the last tornado struck nearly 20 years ago .

“I would guess that there was no clear indication of a warning on the radar in 2005,” said Gass, who was not present at the time.

Due to the fast-moving storm, residents were urged to seek shelter, but few people in the area have basements.

“The most important thing we tell people in the city is to put up as many walls as possible between ourselves and the outside world,” said meteorologist Dalton Behringer.

According to the weather service office, more than 30 centimeters of snow fell at some Lake Tahoe ski resorts, and a wind gust of 112 miles per hour (181 km/h) was recorded at the Mammoth Mountain ski resort south of Yosemite National Park in Reno, Nevada. Up to 91 centimeters of snow was forecast for the mountain peaks of the Sierra Nevada.

The Tahoe Live Music Festival at Palisades Tahoe ski resort in California was scheduled to go ahead as planned on Saturday and Sunday despite a winter storm warning for the region. According to the festival’s website, Lil Wayne was scheduled to perform Saturday night, with Diplo headlining Sunday.

A winter storm warning was set to expire at 10 p.m. Saturday, but an avalanche warning remained in effect until the following night for elevations above 8,000 feet (about 2,400 meters) around Tahoe.

Interstate 80 was closed Saturday for an 80-mile (130-kilometer) stretch from Applegate, California, to the Nevada line west of Reno. The California Highway Patrol reopened the road this afternoon to passenger vehicles with chain or four-wheel drive and snow tires.

The storm in the Midwest caused at least one death. The Washington County Sheriff’s Office in Nebraska said a 57-year-old woman died after she lost control of her pickup truck and struck an oncoming truck on Highway 30 near Arlington. The other driver suffered minor injuries.

Businesses announced plans to open late Saturday as temperatures rose so high in the afternoon that ice melted in most places.

“Fortunately, some warmer air is getting in behind it, so it’s temporary,” said Dave Cousins, a meteorologist at the National Weather Service office in Davenport, Iowa.

Local news outlets reported that tens of thousands of people in western Washington state lost power Saturday as the system dumped rain and gusty winds.

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Associated Press reporters Olga R. Rodriguez in San Francisco, Julie Walker in New York, Becky Bohrer in Juneau, Alaska and Scott Sonner in Reno, Nevada contributed.