SEATTLE—Northern California and parts of the Pacific Northwest are bracing for what is expected to be the most impactful storm the region has seen in nearly two decades, with strong winds starting to cause power outages Tuesday evening.
The Weather Prediction Center issued excessive rainfall risks beginning Tuesday and lasting through Friday as the strongest atmospheric river—a large plume of moisture—that California and the Pacific Northwest has seen this season bears down on the region. The storm system is considered a “ bomb cyclone,” which occurs when a cyclone intensifies rapidly.
The areas that could see particularly severe rainfall will likely reach from the south of Portland, Oregon, to the north of the San Francisco area, said Richard Bann, a meteorologist with the National Weather Service Weather Prediction Center.
“Be aware of the risk of flash flooding at lower elevations and winter storms at higher elevations. This is going to be an impactful event,” he said.
Hurricane-force winds, which are gusts above 75 mph, could be felt along the Oregon coast, according to the National Weather Service in Medford, Oregon. And near Seattle, conditions for a “mountain wave” are shaping up, bringing large, low elevation wind gusts that could cause widespread power outages and downed trees, said Larry O’Neill, director of the Oregon Climate Service and Oregon State University associate professor.
“This will be pretty strong in terms of the last 10 or 20 years,” he said. “We’ve only seen a couple storms that have really been this strong.”
More than 45,000 customers were without power in western Washington, according to poweroutage.us, as strong winds ramped up and snow in the Cascade Mountains began falling Tuesday evening.
The National Weather Service in Seattle said a wind speed of 51 mph was recorded at Ediz Hook, a 3-mile-long sand spit northwest of the city that extends from the northern shore of the Olympic Peninsula at Port Angeles into the Strait of Juan de Fuca. Winds were expected to increase in western Washington throughout the evening, the weather service said.
In northern California, flood and high wind watches went into effect Tuesday, with up to 8 inches of rain predicted for parts of the San Francisco Bay Area, North Coast and Sacramento Valley.
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.
“Numerous flash floods, hazardous travel, power outages and tree damage can be expected as the storm reaches max intensity” on Wednesday, the Weather Prediction Center warned.
In Northern California’s Yolo County, crews spent Monday clearing culverts, sewers and drainage ditches to avoid clogs that could lead to street flooding. Mesena Pimentel said she hopes the efforts prevent a repeat of floods last February that inundated her property near Woodland.
“We had about ten inches of water in our garage, had a couple gophers swimming around,” Pimentel told KCRA-TV. Woodland city officials set up two locations where residents could pick up free sandbags. Authorities urged people to stock up on food and charge phones and electronics in case power goes out and roads become unpassable.
Meanwhile, Southern California will see dry conditions this week amid gusty Santa Ana winds that could raise the risk of wildfires in areas where crews are still mopping up a major blaze that destroyed 240 structures. The Mountain Fire, which erupted Nov. 6 in Ventura County northwest of Los Angeles, was about 98 percent contained Monday.
Winds will calm by the end of the week, when rain is possible for the greater Los Angeles area.
In southwestern Oregon near the coast, 4 to 7 inches of rain is predicted—with as much as 10 inches possible in some areas—through late Thursday night and early Friday morning, Bann said. The National Weather Service issued a flood watch for parts of southwestern Oregon through Friday evening.
A high wind warning has been issued for the north and central Oregon coast beginning at 4 p.m. Tuesday with south winds from 25 mph to 40 mph, with gusts to 60 mph expected, according to the weather service in Portland. Gusts up to 70 mph are possible on beaches and headlands. Widespread power outages are expected with winds capable of bringing down trees and power lines, the weather service said. Travel is also expected to be difficult.
Washington could also see strong rainfall, but likely not as bad as Oregon and California. From Monday evening through Tuesday, some of its coastal ranges could get as much as 1.5 inches of rain, Bann said.
The weather service warned of high winds from Tuesday afternoon until early Wednesday for coastal parts of Pacific County, in southwest Washington. With gusts potentially topping 35 mph—and likely faster near beaches and headlands—trees and power lines are at risk of being knocked down, the Pacific County Emergency Management Agency warned.
A blizzard warning was issued for the majority of the Cascades in Washington, including Mount Rainier National Park, starting Tuesday afternoon, 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.
Transportation officials in Washington told ferry riders to expect bumpy rides on Tuesday and said motion sickness medication might be helpful due to rough seas. Service on at least one route was temporarily halted by Tuesday afternoon because of stormy weather, Washington State Ferries said in social media posts.
Officials also urged motorists to consider delaying travel around the state until Wednesday because of high winds and heavy snow expected in the mountains.
“It will only be a winter wonderland in the sense that you’ll be wondering where the heck you are on any given patch of land,” the Washington State Department of Transportation said on social media.
By Hallie Golden and Christopher Weber