Winter is making a late-season return to Western Washington as an atmospheric river moves into the region Wednesday night through Thursday, bringing heavy mountain snow, strong winds up to 55 mph, and the potential for power outages across Puget Sound.
Western Washington has already seen a return to wintry conditions over the past few days, including brief lowland snow in the North Sound on Tuesday morning. The Cascades are covered in fresh snow, with nearly 3 feet reported at Stevens Pass in the past 48 hours. An extended plume of moisture, known as an atmospheric river, is expected to move into the Northwest tonight through Thursday. This is not a Pineapple Express-style system, as it is oriented straight across the Pacific rather than tapping into warmer air near Hawaii. That means steady precipitation, but snow levels should remain near pass level instead of rising significantly.
Snow falling in the mountains will intensify later Wednesday. A winter storm warning is in effect for the Cascades, where an additional 1 to 2 feet of snow is expected in the next 24 hours. In the lowlands, periods of cool March rain are expected on Wednesday, with damp conditions for both the morning and evening commutes. High temperatures will reach about 50 degrees in the metro area, close to normal for this time of year.
By Wednesday evening, a rapidly strengthening area of low pressure will move through Western Washington. Southerly winds of 30 to 50 mph, with gusts up to 55 mph, are expected across the region, including along the coast and through Puget Sound. The strongest winds between Kitsap and King counties are expected between 7 p.m. and 11 p.m. A wind advisory is in effect, and gusty conditions could cause tree damage and power outages.
As the storm moves east, winds will shift to the west in the Strait of Juan de Fuca and the San Juan Islands. Gusts of 40 to 55 mph are possible in areas such as Oak Harbor, Port Angeles, and Anacortes. Strong winds combined with heavy mountain snow have prompted a blizzard warning for parts of the Cascades and Olympics from 6 p.m. Wednesday to 5 a.m. Thursday. Winds could exceed 60 mph near mountain peaks and remain strong near the passes. Travel across the Cascades is expected to be hazardous on Wednesday night.
By Thursday, winds will ease, but rain in the lowlands and snow in the mountains will continue. Snow levels are expected to remain near 2,000 feet through Thursday and Friday, adding to late-season snowfall at the passes and ski areas. Another push of colder air is expected Friday night into Saturday, lowering snow levels to about 500 feet by Saturday morning. Some brief, light accumulations of lowland snow are possible. High temperatures on Saturday will struggle to rise much above the lower 40s. Conditions are expected to improve Sunday and Monday, with drier weather and increasing sunshine just in time for St. Patrick’s Day. Highs could approach 60 degrees by Monday afternoon.
