Over 8 inches of rain pummeled the Pacific Northwest in 48 hours, triggering rivers -- and then homes -- to flood.

       In Whatcom County, Washington, in the northwest part of the state along the Canadian border, about 500 people were displaced Monday due to flooding, the Whatcom County Sheriff's Office said.

       "Extensive search and rescue efforts" were conducted throughout Monday, including by boat to reach residents in deep areas, the sheriff's office said.

       Elaine Thompson/AP

       Dale Archer, left, leads his daughters Myranda and Krysten Archer through floodwater, Nov. 15, 2021, in Sedro-Woolley, Wash. The heavy rainfall of recent days brought major flooding of the Skagit River that is expected to continue into at least Monday evening.

       In Bellingham, in Whatcom County, the flooding and mudslides closed Interstate 5 overnight.

       Flooding also shuttered Highway 5 in British Columbia, with one official calling the conditions "a disaster waiting to happen."

       B.C. Ministry of Transportation via Reuters

       An aerial view shows a washed out bridge on the Coquihalla Highway as a flood sweeps through, near Carolin Mine Road, British Columbia, Canada, Nov. 15, 2021.

       High winds -- with gusts up to 77 mph -- toppled trees and knocked out power. An 18-wheeler was nearly knocked off a bridge.

       Ted S. Warren/AP

       People walk past a downed power pole blocking a street in Seattle after it fell into an office building during a storm, Nov. 9, 2021. The damage came as strong winds and rain blew through the Northwest and a high-wind advisory was issued for the Seattle metro area, areas along the Washington coast and the Cascade Mountains.

       Tuesday morning, the rain and snow showers will begin to taper off, with conditions improving by the afternoon. But major river flooding will still be an ongoing threat, and a flood watch remains in effect through Tuesday afternoon in parts of western Washington.

       MORE: Floodwater safety tips

       The Skagit River in Mount Vernon is experiencing major flooding. The river is expected to rise to a crest of 37.6 feet by Tuesday afternoon, topping the 1990 record crest of 37.4 feet.

       A winter weather advisory is also in effect; over 1 foot of snow possible in the highest elevations -- above 1,500 feet -- in western Washington.