NEW YORK — A major storm swept across the northwest United States, battering the region with strong winds and rain, causing widespread power outages and downing trees that killed at least one person, according to The Associated Press on Wednesday.

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 has seen this season overwhelmed the region.

The storm system is considered a “bomb cyclone,” which occurs when a cyclone intensifies rapidly.

Rainfall of 12 to 16 inches (30 to 40 centimeters) was expected over far northern California and far southwest Oregon into Friday, the center said. The intensity was expected to peak Thursday, with flash flooding, rock slides and debris flows likely.

Heavy, wet snow was expected to continue along the Cascades and in parts of far northern California. Forecasters warned of blizzard and whiteout conditions and near impossible travel at pass level due to accumulation rates of 2 to 3 inches (5 to 7.6 centimeters) per hour and wind gusts of up to 65 mph (105 kph).

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