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Weekend storm to unload widespread heavy rain in western US

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A large storm will affect much of the western United States with drenching rain, gusty winds and high country snow this weekend into next week.

Following a break of dry and tranquil conditions during Thursday and Friday, a new storm will roll ashore Friday night and will not be in a hurry to leave.

Static US Late Week


"The storm this weekend will be the latest in a series of major storms to affect the West Coast this winter," according to AccuWeather Senior Meteorologist Brett Anderson. "The storms are piping a river of moisture into the region from the Pacific Ocean and will go a long way toward drought relief but at a price."

Storm to unleash localized flooding, damaging winds and avalanche risk

Unlike the storm along the West Coast at midweek, which has been concentrated over northern California and southern Oregon, the impacts from the storm this weekend will be significant, far-reaching and long-lasting.

The storm this weekend will cause disruptions to travel due to wet conditions on the highways and low cloud ceilings and gusty winds at area airports over much of the Interstate 5 corridor.

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Initially, rain and mountain snow will affect areas from northern California to southern Oregon, like the most recent storm. However, rounds of rain and mountain will spread northward through Washington Saturday and Saturday night.

Cities that can expect multiple days of wet weather from the storm include San Francisco, Sacramento and Fresno, California, as well as Portland, Oregon, and Seattle.

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Enough rain can fall to cause urban flooding, as well as raise the risk of mudslides in burn scar areas.

Snow levels will be significantly higher during the bulk of the storm this weekend, when compared to recent storms, according to AccuWeather Storm Warning Meteorologist Alexandria Davis.

"As a result, some of the snow can rapidly melt at intermediate elevations and lead to the potential for stream flooding in some cases," Davis said.

The varying temperatures and dry versus wet snow can also elevate the avalanche risk in the high country. Snow levels will fall to pass levels of the Cascades and Sierra Nevada on Monday.

AP Calif. Drought Snowpack Survey

Frank Gehrke, chief of the California Cooperative Snow Surveys Program for the Department of Water Resources, conducts the first snow survey of the season at Phillips Station Tuesday, Jan. 3, 2017. (AP Photo/Rich Pedroncelli)


The highest elevations of the Cascades and Sierra Nevada will pick 1-2 feet of snow from the storm. This will be on top of the 2-3 feet of snow being delivered in some areas at midweek.

While wind-induced waves along the coast will not be extreme, minor coastal erosion is possible and seas will become dangerous for small craft.

Winds can become strong enough, when enhanced by terrain effects as to down trees and potentially lead to sporadic power outages.

Some rain will also expand southward into parts of Southern California, including the Los Angeles and San Diego areas by Monday afternoon. However, unlike that of areas farther north, rainfall will be of rather short duration in most cases.

Rain, ice to slam Great Basin and Intermountain West

Areas east of the Sierra Nevada and Cascades can expect the greatest impacts from the storm from late this weekend into the middle of next week.

Since the weekend storm will be a warmer and slower-moving system when compared to others recently, mostly rain or a change to ice and then rain will occur at lower elevations of the Great Basin and the interior Northwest.

Rain will cause existing snow on the ground to turn to slush, in cities such as Spokane, Washington; Medford, Oregon; Boise, Idaho; and Salt Lake City. Where piles of snow are blocking storm drains, minor urban flooding can result.

Similar to areas within 200 miles of the coast, changing snow levels over the mountains can raise the risk of avalanches in the high country of the Intermountain West.

As one storm finally leaves the coast, yet another potent storm will roll in from the Pacific Ocean a few hours later during the middle of next week.