Multiple storms to keep flood risk high in Pacific Northwest

By Jessica Storm, AccuWeather,

After months of heat waves and drought, weather in the Pacific Northwest has flipped completely to flooding rain and gusty storms. AccuWeather forecasters say the trend of gusty, stormy conditions in the northwestern United States and British Columbia, Canada, is expected to continue with not one, but two storms aiming for the region.

"An atmospheric river led to major flooding and washed out roads last week in Washington state and British Columbia," said AccuWeather meteorologist Ryan Adamson, adding that another is on the way.


Northwestern Washington, in particular, could be the hardest-hit area in the U.S., as it has already received more rainfall this month (just over 9 inches) than it typically reports throughout the entire month of November (about 6.30 inches). Since September, rainfall amounts have been above average by 50 in Seattle. Portland, Ore., and Spokane, Wash., are just two of the other cities with rainfall amounts for November that are already above normal.


"Moisture will continue to clip western Washington through Monday, acting to bring near- to above-normal precipitation," said AccuWeather lead long-range meteorologist Paul Pastelok.

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Much of British Columbia has also hit a peak in precipitation, including Vancouver, which has received nearly 175 of its average rainfall this November. This could continue to make the situation hazardous as the soil there is saturated and gusts of winds can easily bring down trees on power lines and roadways.

Rain is forecast to overspread in the Olympic Peninsula before sunrise on Saturday morning. The rain will continue to move into Seattle, Portland and Vancouver throughout the day. Rain is also expected to continue on Saturday night, with some snowflakes mixing in at the highest elevations of the Idaho and Montana Rockies. Heavy snow is anticipated along the higher elevations of the mountains in central British Columbia, with up to 18 inches possible.

"Only the highest elevations in British Columbia will receive snow, as most of the precipitation will fall as rain," Adamson emphasized.

The heaviest rain is forecast to fall on the Olympic Peninsula and southern Vancouver Island, along with the northern Cascades into Canada. By Monday morning, there can be 4 inches to 6 inches of rain total in these areas with an AccuWeather Local StormMax&trade of 12 inches of rain.

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Elsewhere, from northwestern Oregon to north of Terrace, British Columbia, a widespread 1 inch to 2 inches of rain is expected, including in Seattle. Vancouver could receive 2 inches to 4 inches, while areas to the east that were recently decimated by flooding and landslides are likely to border on the higher amounts.

"Any additional rain can exacerbate ongoing flooding and slow the receding of rivers," Adamson said. Some of the heaviest rain could cause rivers to rise again, he added. Landslides are also a concern with this storm along with possible road closures.

As of early Friday, the Skagit River in Washington was at major flood stage near the city Mount Vernon and the town of Concrete. Several other rivers in the region were at moderate flood state, according to the National Weather Service.

Rain can continue early next week, as the next storm that poses a serious flooding risk is set to arrive Monday night. This system is expected to steer northward, dropping less rainfall in cities such as Seattle but bringing more rain to places such as Vancouver into Wednesday morning.

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Earlier in the year, residents of the Pacific Northwest may remember a very different picture. Before the seemingly endless stream of storms arrived, this region experienced brutal heat waves and record dry spells. The month of August brought only 11 of average rainfall to Seattle and only 9 to Portland.

Much of the West will have above-average temperatures during this weekend while the anticipated storm moderates temperatures in Washington and areas farther north, according to Pastelok.

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