SANTA ROSA, California — A severe storm battered Northern California with rain and snow Wednesday night, threatening to cause flash flooding and landslides in the latest wave of damaging weather to wash over the West Coast.
The National Weather Service extended its flood watch through Saturday for areas north of San Francisco as the strongest atmospheric river – a large plume of moisture flowing onshore – that California and the Pacific Northwest have seen engulf the region this season. The storm system winds released the night before, there were two deaths and hundreds of thousands of people without power in Washington state.
Up to 16 inches of rain (about 41 centimeters) was forecast in Northern California and southwestern Oregon through Friday. By Wednesday evening, some areas in Northern California had experienced heavy rain, including Santa Rosa, where about 5 inches (13 centimeters) had fallen in 24 hours, according to Marc Chenard, a meteorologist with the National Weather Service.
Dangerous flash floods, rockslides and debris flows were possible, officials warned. About a dozen small landslides had occurred in Northern California in the past 24 hours, including one on Highway 281 on Wednesday morning that caused a car crash, Chenard said.
The National Weather Service in the Bay Area warned people that the atmospheric river was focused on the North Bay and that “heavy rain was expected Thursday through Friday. This will result in mudslides and road closures.”
The storm system, which first struck on Tuesday, is considered a “ bomb cyclone”, which occurs when a cyclone rapidly intensifies.
A winter storm watch was in place for the northern Sierra Nevada above 3,500 feet (1,066 meters), where 38 inches of snow was possible over two days. Wind gusts could reach up to 121 kilometers per hour in mountain areas, forecasters say.
The storm had already dumped more than a foot of snow along the Cascades by Wednesday evening, according to the National Weather Service. Forecasters warned of snowstorms and whiteout conditions and near-impossible travel at pass level.
In Washington, there were nearly 376,000 reports of power outages on Wednesday evening, due to high winds and rain the night before, according to poweroutage.us. Falling trees struck homes and littered roads in western Washington, killing at least two people. One woman in Lynnwood was killed when a large tree fell on a homeless encampment, while another woman in Bellevue was killed when a tree fell on a house.
More than a dozen schools in the Seattle area were closed Wednesday, with some choosing to extend those closures through Thursday.
In California, there were reports of nearly 21,000 power outages on Wednesday evening.
Southbound Interstate 5 was closed Wednesday morning for an 11-mile stretch from Ashland, Oregon, to the California border due to extreme winter weather conditions in Northern California, the Oregon Department of Transportation said. It was expected to be a prolonged closure, the department said.
According to Flight Aware, hundreds of flights were delayed and dozens were canceled at San Francisco International Airport.
The weather service has issued a flood warning for parts of southwestern Oregon through Friday evening, while rough winds and seas temporarily shut down a ferry route in northwest Washington between Port Townsend and Coupeville.
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Golden reported from Seattle.