Drenching storms triggered mudslides and flooding in the Pacific northwest on Wednesday, knocking out power to thousands of people and leaving two women dead in Oregon, authorities and local media reported.

Portland has endured more than 5 inches of rain in three days, nearly as much as all of December in a typical year, and Seattle exceeded its normal December rainfall tally in just 8 days, the National Weather Service said.

The service said mountainous areas of Oregon and neighboring Washington state, where Governor Jay Inslee declared a state of emergency on Wednesday, have received more than a foot of rain.

The record-breaking storms opened sinkholes in several major roads, caused rivers to spill over their banks and closed roads and schools for a third day in the worst-hit areas across the region.

The Weather Service forecast said a number of major Puget Sound area rivers had overflowed, and it issued warnings of other floods.

National Weather Service meteorologist Gerald Macke said he could not definitively say whether the parade of storms was linked to the El Nino weather pattern. "Once or twice every winter we get prolonged flooding in our region, kind of like how in Oklahoma they get tornadoes."

A 60-year-old Portland woman died when a tree fell on her house, according to the city's fire department.

Another woman drowned on Wednesday when her car became submerged in standing high water in Clatskanie, in the state's north, the Oregonian reported.

In Clackamas County, firefighters waded through hip-deep water and used rafts to help rescue people trapped in their homes, authorities said.

Outside Tacoma, Washington, emergency officials rescued several people who were swept into the swollen Puyallup River overnight on Wednesday from a bankside homeless encampment, police said.

Washington transportation officials said interstate highway travel between Portland and Seattle would be closed until at least Thursday morning, as engineers needed to evaluate an unstable hillside after boulders fell onto the freeway north of Portland.

Puget Sound Energy, a utility that serves Seattle, reported 37,000 customers were without electricity after fierce winds and hail hit the city.

Storms have also left 26,000 customers without power in the Portland area, utility Portland General Electric said.

Last December, harsh weather was blamed in the deaths of a homeless man camping with his son near Ashland, Oregon, as well as a passenger in a car that swerved into a tree in Portland.-Reuters