(By Brad Lendon, CNN) — Seattle could see one of its largest snowfalls since the 1940s as twin winter storms move over the Pacific Northwest, according to the National Weather Service.
Between 4 and 8 inches of snow could hit the Seattle-Tacoma area Wednesday, the National Weather Service said, with 5 to 10 inches of snow forecast for the state’s southwest interior, including Olympia.
Precipitation moving in from the south and west is combining with cold air moving south from Canada to create the heavy snowfall, said Dustin Guy, a meteorologist at the weather service’s Seattle office. If snowfall amounts top 7 inches, the winter weather event will rank among Seattle’s 10 worst since the early 1940s, he added.
While that amount of snow is no problem in places that receive snow regularly, heavy snowfall is relatively rare in Seattle, where steep hills can make winter travel treacherous.
Nevertheless, city officials maintain they are prepared for the storm, said CNN’s Thelma Gutierrez. De-icing has begun on bridges and overpasses, some emergency shelters were opened, schools were closed and some flights were canceled.
High-wind warnings were in effect along the coast, where winds could gust to hurricane force — knocking down trees and causing power outages, said CNN meteorologist Taylor Ward.
Wednesday’s snowfall in Seattle may equal its annual average, Ward said.
“They’re going to see significant accumulations, that’s for sure,” said CNN meteorologist Rob Marciano.
Mountainous areas of the Pacific Northwest will see even more snow, with the largest accumulations on the eastern slopes of the Cascades, according to the weather service. Significant snowfall is expected across southern Washington, northwest Oregon and into western Idaho. Portland, Oregon, could see about 3 inches, according to Ward.
From late Tuesday through early Thursday, 2 feet to 3.5 feet of snow is forecast for the mountains east of Seattle, Guy said. Mount Rainier could see 10 feet of snow by Friday.
The first storm moved into the area Monday and Tuesday. The second and stronger storm was forecast to hit Wednesday into Thursday.
“It’s pretty big when you get back-to-back storms like that,” weather service meteorologist Roger Cloutier said.
Winter storm warnings Wednesday touched portions of eight states, stretching into Montana, Utah and Wyoming.
Scattered areas near Easton, Washington, along Interstate 90 in the Cascade Mountains 55 miles east of Seattle, have already received 32 inches of snow, Cloutier said.
The snowfall extends south into Oregon, with as much as 18 inches forecast for the Bend area. CNN affiliate KTVZ in Bend said an earlier round of snow over the weekend gave a boost to local ski resorts but also created dangerous driving conditions that left at least one motorist dead.
Those conditions were expected to worsen.
“Expect extreme travel difficulties to develop on Wednesday,” the weather service said, advising those who must take to the roads during the storm to carry a flashlight, blankets and extra food and water.
Portland was also under a flood advisory early Wednesday, as warmer air moved heavy rain into the area, according to the National Weather Service. High winds were also forecast for the area.
The Washington State Department of Transportation said 1,250 workers will use nearly 500 pieces of equipment statewide to treat and plow roadways.
Alaska Airlines said it is canceling 38 flights Wednesday because of the heavy snow expected to hit the area.
CNN affiliate KING reported that Seattle Public Schools opted to close all schools two hours early.
The heavy snowfall will be followed by rain, which could produce accumulated water and urban flooding, Guy said.
“It’s just gonna be a mess all around,” he said of the coming few days in the Seattle area.
Cloutier said even though computer models are trending colder and colder for the coming days, the heavy snow will eventually pose a flooding threat.
“When the snow does finally melt, you can almost guarantee there will be some flooding somewhere,” he said.