Atmospheric River Brings Rain, Snow and Power Outages to California and West Coast

A wind-whipped storm was bringing heavy rain and snow to Northern California early Thursday, after knocking down trees, snarling highways and transit and leaving tens of thousands of people without power.

More intense rain and snow was forecast for Thursday evening, raising the risk of flash floods and landslides in the region, meteorologists said. The Weather Prediction Center said the total rainfall in Northern California could reach 12 to 16 inches by Friday morning.

The deluge, which has killed at least two people in the Pacific Northwest, was expected to stretch into the weekend. It was the season’s first major atmospheric river, a type of storm that can deliver large amounts of water from the Pacific Ocean.

The National Weather Service warned of a high risk that 210,000 people in Eureka, Calif., and the area south of the city were in a zone that would receive excessive rainfall, with possible flash floods Thursday evening.

The storm brought some of the worst damage to the Seattle area, where heavy wind gusts tore down power lines and knocked out substations late Tuesday, leaving half a million customers without electricity. “This is a major storm the likes of which we haven’t seen in over a decade,” said Melanie Coon, a spokeswoman for Puget Sound Energy.