Atmospheric river to kick off winter storm season with a bang in British Columbia, Washington

The first potent storm of the autumn and winter season for British Columbia and part of Washington was a doozy. Enough rain fell to cause flash flooding and cause travel issues on Saturday in the Vancouver metro area.

"A plume of moisture will extend from well out over the Pacific Ocean and be directed at southern British Columbia and the northwestern corner of Washington," AccuWeather Senior Meteorologist Brett Anderson said. "It will behave like a giant firehose or what weather folks refer to as an atmospheric river."

The storm began to affect the region on Friday continued through the weekend, with one surge that lasted into Saturday and a second round on Sunday. Light rain and showers are expected to linger Monday.

"Rainfall of 5-15 inches will easily fall on the west-facing slopes of Vancouver Island with a general 4-8 inches on the western slopes of the Olympics in northwestern Washington and the lower slopes of the Coastal Range in southern British Columbia," Anderson said. "Up to 18 inches of rain may pour down in the wettest spots."

At the Vancouver, British Columbia airport this past Friday through the weekend, 4.69 inches of rain was recorded. On western Vancouver Island, reports ranged from 6 to around 15 inches in the same time period. Seattle, Washington sits in the shadow of the Olympic Mountain Range and only picked up 0.23 inches during the event.

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In British Columbia, snow levels fluctuated between 3,000 and 4,000 feet at the onset of the storm on Friday, rose to 6,000 to 7,000 feet on Saturday, then fell back to 5,000 feet or so on Sunday.

"Snow levels in the Washington Cascades were generally around 8,000 to 10,000 feet," AccuWeather Meteorologist Danielle Ehresman said.

Where heavy snow initially falls in the higher elevations and switches to heavy rain, the flooding of streams and rivers could be rapid.

"From 2-4 feet of snow can easily pile up in the high country of the coastal range north of Vancouver," Anderson said.

The storm was also accompanied by strong winds that quickly ramped up on Friday and lingered into the weekend. With winds blowing perpendicular to the coast for a significant part of the storm, resulting in waves heights dangerous for small craft on the open Pacific and hazardous levels on the straits surrounding Vancouver Island and the mainland.

Following a break for most of this week, a series of Pacific storms may take aim at part of British Columbia and the northwestern United States this weekend.

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