SEATTLE— November is statistically the wettest month of the season for the Pacific Northwest, and it’s sure acting like it this year, with multiple atmospheric river-type storms on the docket to kick off the first week.
One storm is already in progress on Saturday, with steady rains lingering from the system that began by soaking trick-or-treaters on Halloween night and causing the area’s mountain-fed rivers to rise. Over 2 inches of rain fell in the mountains, with another inch or so expected through the first half of Saturday.
With rivers at least nearing flood stage, Flood Watches are in effect for several rivers that feed off the Olympic and Cascade Mountains, though any flooding that occurs looks to be minor.
Meanwhile, a low pressure center developing along the front Saturday morning will add a round of powerful wind gusts to the equation. Wind Advisories are in effect for a large portion of Western Washington, including the Seattle area, through the early afternoon. Wind gusts could reach up to 45-50 mph, triggering the risk of scattered power outages.
While this first storm moves out later Saturday, more atmospheric river-type storms lurk through the week amid a very active weather pattern in the Pacific Ocean.
By early next week, a strong area of low pressure will continue to spin in the Bay of Alaska before gradually shifting eastward into Canada. This system will once again draw moisture northward from the Pacific Ocean, directing it toward the Pacific Northwest through late Tuesday.
This atmospheric river is forecast to be very strong as it hits the Pacific Coast, though with the heaviest rains more focused on the Oregon coast this time. Right now, forecasts from the Center for Western Water and Weather Extremes are projecting this event to be a level 5/5 on their atmospheric river scale for locations in Oregon.
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The heaviest rainfall will likely arrive along the coastal regions of Washington and Oregon by Wednesday. Between Tuesday and Thursday, widespread rainfall totals of 3 to 5 inches are expected along the coasts, with locally higher amounts of 5 to 8 inches possible across the Olympic Mountains.
Farther south, from southern Oregon into northern California, lighter totals of 1 to 2 inches are anticipated. Flash flooding will be possible, especially into Wednesday afternoon, as the heaviest rain moves slowly down the Northwest coastline.
Long-range forecasts suggest yet another atmospheric river-type storm lurks later in the week or over next weekend, and no sign of a drier weather pattern in the days beyond.
