Flood watches hit Pacific Northwest, polar vortex brings icy weather east

WASHINGTON – Heavy rainfall is expected to drench the Pacific Northwest this week, bringing chances of river flooding and landslides to the area, as parts of the Midwest and eastern United States brace for another round of arctic cold.

Flood watches are in effect for western Oregon and Washington state, which could see as much as 7 inches of rainfall in some areas through Friday, according to the National Weather Service. As rain pummels the region, rivers, creeks and streams could rise and overflow, and flooding is possible in some urban areas.

Overly saturated soil also brings increased risk of landslides and dangerous, fast-moving currents of debris.

Meanwhile, forecasters are expecting another round of chilly temperatures to settle over midwestern and eastern states, courtesy of a polar vortex system. The wave of arctic air has the potential to create flurries and snowfall in some areas.

Here’s a look at the forecast ahead.

Flood watches in Pacific Northwest

A series of atmospheric rivers that move water through the sky are forecast to douse coastal areas of Washington and Oregon beginning Sunday and stretching through the week, according to the National Weather Service.

Scattered instances of flooding are possible Monday, though the heaviest rainfall is expected later in the week, forecasters say. Up to 21/2 inches of rain are expected to fall Monday in southwest Washington, and in areas around Portland, Oregon, and Vancouver, Canada, while communities along the coast could see between 4 and 7 inches of rain.

The storm is forecast to drop more than a foot of snow in high-elevation areas in the Cascade and Northern Rocky Mountains.

Freezing temps on the way

Millions of Americans from the Midwest to the East Coast will see another wave of freezing temperatures, AccuWeather meteorologists say.

The cold air system is caused by the breakdown of a polar vortex – a large area of low pressure and cold air that surrounds Earth. When the polar vortex in the northern hemisphere expands, it sends arctic air south.

AccuWeather forecasters expect the latest surge of cold air to move from the Midwest on Sunday toward the East Coast by Monday. The blast could send temperatures below zero degrees Fahrenheit on Monday morning in the Midwest. In other areas, temperatures could drop into the teens.

Light snow is possible in areas with frigid temperatures, though larger snowstorms are unlikely, according to AccuWeather Lead Long-Range Meteorologist Paul Pastelok.

“The fast movement of the waves of cold air will generally prevent giant snowstorms from developing,” Pastelok said. “However, the best chance for a rapidly intensifying storm on the East Coast would be around Dec. 12 or so.”

The National Weather Service’s long-range forecast for Dec. 10 through Dec. 14 suggests the potential for snow over the northern Plains and Midwest, Great Lakes and the Northeast.

This article originally appeared on USA Today

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