SAN FRANCISCO — A powerful storm churned down the West Coast Thursday, bringing strong gales and much-needed rain and snow that caused widespread blackouts in Northern California and whiteouts in the Sierra Nevada.

The brunt of the storm hit the San Francisco Bay Area, flooding freeways, toppling trees and keeping thousands of people home from work and school.

“It’s a big storm, as we expected, and it’s headed south with very powerful winds and heavy rainfall,” said National Weather Service meteorologist Will Pi.

Strong winds felled a tree in Oregon, killing a homeless man, 40-year-old Phillip Crosby, who was sleeping on a trail. A huge gust blew down an 80-foot fir at a Santa Cruz elementary school, pinning a 6th grader by the arm for 15 minutes until chain saws were used to cut him free.

This “Pineapple Express” storm carried warm air and vast amounts of water in a powerful current stretching from Hawaii to the mainland and up into the mountains, where gusts up to 140 mph blew through passes, damaging homes in the Lake Tahoe area.

The current left San Francisco drenched but balmy, with 60-degree temperatures, about 5 degrees above average for this time of year.

Waves slammed onto waterfronts around the Bay area, ferries were bound to their docks, airplanes were grounded and many schools and businesses told people to stay home.

The gusts made motorists tightly grip their steering wheels on the Golden Gate Bridge, where managers created a buffer zone to prevent head-on collisions by swerving cars.