We talk about it a lot during wind events: "Higher wind speeds in the Northwest Interior".
This is generally the area from roughly Everett north to the Canadian border, and west to Port Townsend, including Whidbey, Camano and San Juan islands.
Other cities would be Anacortes, Bellingham, Mount Vernon, and Burlington.
This area is suceptible to strong southeast winds as a windstorm approaches. While the Olympic Mountains protect areas south of Everett, these areas shaded in yellow are exposed to the coast and southeast winds can race through this region, out the Strait of Juan de Fuca and toward the center of the storm.
This map below shows a rough outline of the Northwest Interior: