LOS ANGELES » A motorist was fatally struck by a tree that toppled as a winter storm moved across California, bringing powerful winds, heavy rain and snow, authorities said today.

The driver was passing by a residential street in Pacific Beach when a large oak tree fell across all four traffic lanes, San Diego Fire and Rescue Capt. Joe Amador said.

The tree, which measured 8 feet in diameter, also crushed three parked cars that were not occupied, he said.

“To the people out here dealing with the rain: be careful, drive slowly and arrive alive,” Amador said.

Strong winds downed dozens of trees and power poles and ripped off rooftops — and in one case, solar panels — across Southern California.

Wind gusts topped 50 mph in the San Diego area and 65 mph in Malibu, according to the National Weather Service. The highest reading of the day was at Whitaker Peak, north of Castaic, where a gust was recorded at 115 mph.

The storm also dropped up to an inch of rain in some places by 4 p.m. Sunday, and forecasters said up to 2 inches of rain was expected in the valleys of Los Angeles County and as many as 3 inches possible for southwest-facing foothills and mountains.

A flash flood watch was issued for foothill neighborhoods underneath wildfire burn areas, triggering fears of possible mudslides and debris flows. The threat subsided by late Sunday as the storm moved out of the area.

Meanwhile, power outages affecting about 140,000 utility customers were reported across the Los Angeles and San Diego area.

Blinding rain briefly brought traffic to a near-standstill on LA freeways. North of the city, a crash during a heavy downpour involving two trucks closed southbound lanes of Interstate 5 near the Grapevine. There were no immediate reports of injuries.

The weather service said the highway corridor will receive 3 to 7 inches of snow by Monday morning and vehicles may be required to travel with tire chains.

The storm also churned up high surf along west and northwest-facing beaches. The rough seas prompted authorities to close the piers at Redondo Beach and Manhattan Beach.

To the north, Interstate 80 near Truckee was closed for more than two hours after 29 vehicles got into a pileup amid snowy conditions, KCRA-TV reported. Flooding created an ice dam that forced the closure of a mountain road, cutting off several hundred residents of Serene Lakes, a community in the Donner Summit area of the Sierra Nevada, Nevada County officials said.

Another rain storm was expected in the San Francisco Bay Area by Sunday evening. A wind advisory was issued warning of winds gusting up to 50 mph.