Heavy rain to return to Seattle, Portland as storm system eyes Northwest
By
Ryan Adamson, AccuWeather meteorologist
Updated Sep 25, 2021 6:30 AM EDT
Snow fell across the northwestern U.S. from Sept. 18-20 as cold air dove over the Rocky Mountains.
Much of the Northwest is dealing with substantial drought following a hot, dry summer, but AccuWeather forecasters say help in the form of a dose of rain and mountain snow is on the way.
A moisture-laden storm managed to put a small dent in that drought last weekend, and a new storm system will take aim at the Northwest late this weekend into early next week as a ripple in the jet stream brings abundant moisture into the region.
Locations in both the interior and coastal Northwest have experienced below-normal precipitation for the past several months. In fact, it was the driest spring and summer on record in Seattle, where records go back 77 years at the Seattle-Tacoma International Airport. That dryness extended farther down the coast as well.
"Seattle received only 11% of its normal precipitation throughout the month of August and Portland, Oregon, reported a measly 9% of average," said AccuWeather Meteorologist Jessica Storm.
According to the United States Drought Monitor, more than 70% of Oregon is dealing with extreme drought conditions, while more than 45% of Washington is in the midst of extreme drought. Similar to worse drought conditions are being reported across much of the western United States.
The dry pattern was briefly interrupted by a storm with drenching rain along much of the Interstate 5 corridor from Washington to Northern California between last Friday and Sunday.
Portland received 2.52 inches of rain between Sept. 17 and Sept. 19. From Sept. 1 through Sept. 19, only 0.80 of an inch typically falls in Portland.
"With the storm coming up from Sunday night to Tuesday, a general 0.50 of an inch to 1 inch of rain is likely to fall at the low elevations along the Interstate 5 corridor in Washington and Oregon, but along west-facing slopes of the Olympics and Cascades, a general 2-4 inches of rain is likely with this storm," AccuWeather Senior Meteorologist Alex Sosnowski said.
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Inland areas received significantly less precipitation from last weekend's storm, relative to coastal areas of the Northwest. Most locations from Spokane, Washington, to Pendleton, Oregon, received a general 0.20 to 0.50 of an inch.
"East of the Cascades in Washington, Oregon and parts of Idaho, a general 0.10 to 0.25 of an inch is likely with locally higher amounts early next week," Sosnowski added.
Some of the higher elevations in Oregon and Wyoming managed to pick up the season's first accumulation of snow with last weekend's storm. And, with the next system, many more locations are expected to receive their first taste of winter.
This system will first impact western Washington and northwestern Oregon with some generally light rain later on Sunday. By Monday, much heavier rain will soak western Washington and western Oregon as a cold front moves ashore. Behind the front, colder air and strong winds will come ashore.
"Snow levels are expected to fall as cool air pushes into the region, and high winds are anticipated mainly along the coast and in the mountains," Storm said.
The storm early next week may have more wind energy with it compared to last weekend’s storm, according to Sosnowski. "Gusts ranging from 30-45 mph are likely along the coast of Washington and northern Oregon,” he said.
Snow is expected to be confined to elevations above 6,000 feet. Since this is generally above pass level, motorists traveling through the Cascades should not have to contend with slushy or snow-covered roads.
Rain and snow showers will become lighter on Tuesday and extend farther inland into Idaho and northwestern Montana before ending on Wednesday. However, that will not be the end of the story for the storm.
"By next Thursday, the storm is forecast to move into the central Rockies and could produce more valley rain and mountain snow," said Storm.
While this would likely mean cold rain for cities such as Cheyenne, Wyoming, and Denver, snow could fall in the higher elevations nearby.
Another system may move into the Northwest next Thursday, although precipitation may largely affect locations farther to the north in southern Canada.
For the latest weather news check back on AccuWeather.com. Watch AccuWeather Network on DIRECTV, DIRECTVstream, Frontier, Spectrum, fuboTV, Philo, and Verizon Fios. AccuWeatherNOW is streaming on Roku and XUMO.
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News / Weather Forecasts
Heavy rain to return to Seattle, Portland as storm system eyes Northwest
By Ryan Adamson, AccuWeather meteorologist
Updated Sep 25, 2021 6:30 AM EDT
Snow fell across the northwestern U.S. from Sept. 18-20 as cold air dove over the Rocky Mountains.
Much of the Northwest is dealing with substantial drought following a hot, dry summer, but AccuWeather forecasters say help in the form of a dose of rain and mountain snow is on the way.
A moisture-laden storm managed to put a small dent in that drought last weekend, and a new storm system will take aim at the Northwest late this weekend into early next week as a ripple in the jet stream brings abundant moisture into the region.
Locations in both the interior and coastal Northwest have experienced below-normal precipitation for the past several months. In fact, it was the driest spring and summer on record in Seattle, where records go back 77 years at the Seattle-Tacoma International Airport. That dryness extended farther down the coast as well.
"Seattle received only 11% of its normal precipitation throughout the month of August and Portland, Oregon, reported a measly 9% of average," said AccuWeather Meteorologist Jessica Storm.
According to the United States Drought Monitor, more than 70% of Oregon is dealing with extreme drought conditions, while more than 45% of Washington is in the midst of extreme drought. Similar to worse drought conditions are being reported across much of the western United States.
The dry pattern was briefly interrupted by a storm with drenching rain along much of the Interstate 5 corridor from Washington to Northern California between last Friday and Sunday.
Portland received 2.52 inches of rain between Sept. 17 and Sept. 19. From Sept. 1 through Sept. 19, only 0.80 of an inch typically falls in Portland.
"With the storm coming up from Sunday night to Tuesday, a general 0.50 of an inch to 1 inch of rain is likely to fall at the low elevations along the Interstate 5 corridor in Washington and Oregon, but along west-facing slopes of the Olympics and Cascades, a general 2-4 inches of rain is likely with this storm," AccuWeather Senior Meteorologist Alex Sosnowski said.
CLICK HERE FOR THE FREE ACCUWEATHER APP
Inland areas received significantly less precipitation from last weekend's storm, relative to coastal areas of the Northwest. Most locations from Spokane, Washington, to Pendleton, Oregon, received a general 0.20 to 0.50 of an inch.
"East of the Cascades in Washington, Oregon and parts of Idaho, a general 0.10 to 0.25 of an inch is likely with locally higher amounts early next week," Sosnowski added.
Some of the higher elevations in Oregon and Wyoming managed to pick up the season's first accumulation of snow with last weekend's storm. And, with the next system, many more locations are expected to receive their first taste of winter.
This system will first impact western Washington and northwestern Oregon with some generally light rain later on Sunday. By Monday, much heavier rain will soak western Washington and western Oregon as a cold front moves ashore. Behind the front, colder air and strong winds will come ashore.
"Snow levels are expected to fall as cool air pushes into the region, and high winds are anticipated mainly along the coast and in the mountains," Storm said.
The storm early next week may have more wind energy with it compared to last weekend’s storm, according to Sosnowski. "Gusts ranging from 30-45 mph are likely along the coast of Washington and northern Oregon,” he said.
Snow is expected to be confined to elevations above 6,000 feet. Since this is generally above pass level, motorists traveling through the Cascades should not have to contend with slushy or snow-covered roads.
Rain and snow showers will become lighter on Tuesday and extend farther inland into Idaho and northwestern Montana before ending on Wednesday. However, that will not be the end of the story for the storm.
"By next Thursday, the storm is forecast to move into the central Rockies and could produce more valley rain and mountain snow," said Storm.
While this would likely mean cold rain for cities such as Cheyenne, Wyoming, and Denver, snow could fall in the higher elevations nearby.
Another system may move into the Northwest next Thursday, although precipitation may largely affect locations farther to the north in southern Canada.
For the latest weather news check back on AccuWeather.com. Watch AccuWeather Network on DIRECTV, DIRECTVstream, Frontier, Spectrum, fuboTV, Philo, and Verizon Fios. AccuWeatherNOW is streaming on Roku and XUMO.
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