SAN FRANCISCO - Strong gales and sheets of rain that knocked out electricity, flooded freeways, and toppled trees in Northern California churned Thursday toward a slide-prone Southern California bracing for its own beating.

"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. Its strong winds felled a tree in southern Oregon, killing a homeless man, Phillip Crosby, 40, who was sleeping on a trail.

Los Angeles expected rain by the end of the day Thursday.

Already, one apartment complex in a spot prone to mud slides in Riverside was evacuated. In the San Bernardino National Forest, lumber workers were loading concrete weights onto the stacks to keep them from blowing away and piling sandbags in front of their shop doors.

"We're getting ready this afternoon because it's supposed to come in tonight," said Jim Maddox, a worker at Rim Forest Lumber. "You expect the worst and hope for the best."

The San Bernardino Mountains have been razed by wildfires and were already doused by a storm last week, making them particularly vulnerable to mud flows.

The Port of Los Angeles is ready to take on the storm, spokesman Phillip Sanfield said. "If heavy rains come, we've got construction crews to check on the docks; police can deal with flooding streets," he said.

Denise George, who sells boats in Marina Del Rey, worried mostly about the wind: "We make sure the halyards are secure, the canvasses are fastened so nothing gets blown off or opened up, so, yes, we are battening down the hatches for sure."

Throughout the San Francisco Bay Area on Thursday, waves slammed onto waterfronts, ferries were bound to their docks, some airplanes were grounded, and many schools canceled classes.

Gusting winds had motorists tightly gripping their steering wheels on the Golden Gate Bridge, where managers created a buffer zone to prevent head-on collisions by swerving cars.

The iconic suspension bridge is engineered to swing in cross winds, and engineers were standing by, but "the concern we have right now is more about vehicles," spokeswoman Priya David Clemens said.

An elementary school student was trapped for about 15 minutes when an 80-foot tree fell on him in Santa Cruz. Rescuers with chain saws freed his arm, and he was taken to a hospital in good condition.

Crews worked throughout the day to restore power to as many as nearly a quarter-million people in Northern California. Pacific Gas & Electric's online map showed lights out over thousands of square miles, from Humboldt near the Oregon border to Big Sur on the Central Coast.