A major storm swept across the northwestern U.S., battering the region with strong winds and rain, causing widespread power outages and downing trees that killed at least one person.

The Weather Prediction Center issued excessive rainfall risks through Friday and hurricane-force wind warnings were in effect as the strongest atmospheric river – a large plume of moisture – that California and the Pacific Northwest have seen this season overwhelmed the region. The storm system that started hitting Tuesday is considered a bomb cyclone, which occurs when a cyclone intensifies rapidly.

 Falling trees struck homes and littered roads across northwest Washington. In Lynnwood, Washington, a woman died Tuesday night when a large tree fell on a homeless encampment, South County Fire said in a statement on X. In Seattle, a tree fell onto a vehicle, temporarily trapping someone inside, the Seattle Fire Department reported. The agency later said the person was in stable condition.

“Trees are coming down all over the city & falling onto homes,” the fire department in Bellevue, about 10 miles east of Seattle, posted on the social platform X. “If you can, go to the lowest floor and stay away from windows. Do not go outside if you can avoid it.”

Early Wednesday, over 600,000 houses in Washington state were reported to be without power on PowerOutage.us. The number of outage reports had fluctuated wildly Tuesday evening, likely due in part to several weather and utility agencies struggling to report information on the storm because of internet outages and other technical problems. It wasn’t clear if that figure was accurate. More than 4,000 had lost power in Oregon and nearly 15,000 in California.

As of 8 p.m., the peak wind speed was in Canadian waters, where gusts of 101 mph were reported off the coast of Vancouver Island, according to the National Weather Service in Seattle. Along the Oregon coast, there were wind gusts as high at 79 mph Tuesday evening, according to the National Weather Service in Medford, Oregon, while a wind speed of 77 mph was recorded at Mount Rainier in Washington.

The National Weather Service warned people on the West Coast about the danger of trees during high winds, posting on X, “Stay safe by avoiding exterior rooms and windows and by using caution when driving.”

In Northern California, flood and high wind watches were in effect, with up to 8 inches of rain predicted for parts of the San Francisco Bay Area, North Coast and Sacramento Valley. Twelve-16 inches were forecast for far Northern California and far southwestern Oregon into Friday, according to the National Weather Service Weather Prediction Center. Dangerous flash flooding, rock slides and debris flows were expected.

A winter storm watch was issued for the northern Sierra Nevada above 3,500 feet, where 15 inches of snow was possible over two days. Wind gusts could top 75 mph in mountain areas, forecasters said.

The National Weather Service issued a flood watch for parts of southwestern Oregon through Friday evening, while rough winds and seas halted a ferry route in northwestern Washington between Port Townsend and Coupeville.

A blizzard warning was issued for the majority of the Cascades in Washington, including Mount Rainier National Park with up to a foot of snow and wind gusts up to 60 mph, according to the weather service in Seattle. Travel across passes could be difficult if not impossible.

The Weather Prediction Center said heavy, wet snow would fall along the Cascades and far Northern California. accumulating at rates of two-three inches per hour. That along with gust sup to 65 mph could result in whiteout/blizzard conditions and “near impossible travel at pass level,” the center said.