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Quiet pattern in the Northwest to be disrupted by atmospheric river this week

Courtney Spamer

A break in disruptive weather is expected during the next several days across the northwestern United States -- but meteorologists warn that the tranquil pattern will not last long with storms set to return, and the timing could hinder early holiday travel.

Other than a spotty snow shower or two, the quiet weather pattern began over the weekend.

High pressure will settle in the northern Rockies into Tuesday, continuing to shield most of the Northwest from any wet weather. The only exception would be along the immediate coast of Washington and Oregon, where there may be more clouds along with a spotty shower or two.

During this time, temperatures will hover around normal across the region. High temperatures in the middle to upper 40s are expected along the Pacific coast, while temperatures hold in the 30s for interior parts of the Northwest.

Around midweek is when things will start to change.

A shift in the jet stream will bring some showers along the coast and as far inland as the Cascades from northern Washington to California by Wednesday.

"The jet stream will pull tropical moisture from near Hawaii into the Northwest, with the heaviest rain aimed at Oregon and possibly extreme Northern California," said AccuWeather Senior Meteorologist Brian Thompson, adding that this atmospheric river will fuel abundant precipitation across the region.

A storm will move in Wednesday night and Thursday, spreading rain and mountain snow from west to east across Washington, Oregon and Northern California.

The persistence of moisture streaming in from the Pacific Ocean will increase the threat for flooding across the region.

Widespread rainfall amounts of 1-3 inches will be possible from the western slopes of the Cascades to the coast through Friday night.

"There is the potential for over 6 inches of rain along the southern Oregon coast from late Wednesday into the start of the weekend," Thompson said.

Meanwhile, snow will pile up in the Cascades. Accumulating snow will be possible above 3,000 feet in Washington, and around 5,000 feet in Oregon and Northern California.

"Snow levels will be low enough in Washington state to effect the passes, including Snoqualmie and Stevens," added Thompson.

Rounds of snow could accumulate as much as 6-12 inches, with the highest elevations likely to see over a foot.

Snow extending farther inland will allow the Rockies across Idaho and western Montana to see accumulating snow.

The additional snow in the majority of these areas will be welcome for ski resorts across the region.

The river of moisture may come to an end just before Christmas, helping to bring a break from at least the heavy precipitation days before the holiday.

Download the free AccuWeather app to check the forecast in your area. Keep checking back on AccuWeather.com and stay tuned to the AccuWeather Network on DirecTV, Frontier and Verizon Fios.