An atmospheric "river" over the Pacific Northwest is expected to dump heavy rain and snow over the region in the coming days.

The weather pattern brought gusty winds and broke daily rainfall records in Seattle on Wednesday before it moved into western Oregon on Wednesday night, the National Weather Service said.

Over the next several days, storms are expected to dump up to 2 inches of rain in Portland and 3 to 6 inches of rain on higher terrain in southwest Washington and northwest Oregon.

An atmospheric river is the name meteorologists have given a slow-moving concentrated channel of moisture in the air, said National Weather Service meteorologist Paul Tolleson.

Rivers typically produce heavy downpours and are responsible for as much as half of the West Coast's precipitation between October and April.

Two atmospheric rivers will move over Oregon, the first on Thursday and the second arriving over the weekend, Tolleson said.

As much as three-quarters of an inch of rain is expected to fall Thursday in the Portland area.

The storm will bring more rain to other parts the state, Tolleson said. Through Thursday, from 2 to 4 inches are expected to fall in the Cascades and at the Oregon coast. In the Willamette Valley, up to 1.25 inches are expected.

And that's just the beginning.

The second atmospheric river will be stronger than the first and will bring more rain beginning Saturday, Tolleson said.

"It looks like it's going to be a pretty big rain event for the weekend," he said.

Up to 2 inches of rain are expected in Portland over the weekend. In the Willamette Valley, from .75 to 1.5 inches could fall. High elevations in southwest Washington and northwest Oregon will be hit the hardest, with meteorologists predicting up to 6 inches this weekend.

The heavy rainfall could trigger landslides and debris flows in burn scars from earlier wildfires.

The Chetco Bar fire burn area in southern Oregon is under flood watch Thursday.

Landslides are also possible in the Eagle Creek fire area in the Columbia River Gorge and the Whitewater fire area in the Cascades, the weather service said.

Despite the storms, meteorologists don't anticipate any major flooding. Smaller rivers and creeks may see some minor flooding, the weather service said, particularly in areas where storm drains may be blocked.

Still, Tolleson said, Oregonians should brace themselves for a wet weekend ahead.

"Everybody's going to see a lot of rain," he said.

-- Samantha Matsumoto