PORTLAND, Ore. – Light rain is forecast for much of the Pacific Northwest Wednesday ahead of a more powerful atmospheric river that is set to slam into the region later this week, which, when all is said and done, could drop several inches of rain in coastal areas and several feet of snow at higher elevations.
According to the FOX Forecast Center, new forecasts suggest that the most intense portion of the storm may have shifted farther south, with the strongest impacts targeting southern Oregon and Northern California. Cities including San Francisco and Eureka in California and Medford, Oregon, will see the most intense part of the storm on Saturday and Sunday.
Atmospheric rivers are rainstorms along the West Coast fueled by moisture, typically with tropical origins, carried by the jet stream. These storms are sometimes compared to a river of water vapor in the sky. When an atmospheric river comes ashore, it brings moderate to heavy rainfall for two days or more.
By the end of the week, some parts of Washington could see between 5 and 8 inches of rain, with more widespread areas across the Pacific Northwest picking up between 1 and 3 inches.
The heaviest rainfall is forecast between Friday and Saturday.
With so much rain comes the threat of flooding. A Level 1 out of 4 flash flood threat has been issued by NOAA’s Weather Prediction Center for the Northern California coast, coastal Oregon and parts of western Washington for Friday and Saturday.
For elevations above 5,000 feet in the Cascade Mountains, the storms will mean snow for the mountain passes. Snow accumulations could reach 2 feet or more in some areas, but it’s still early to tell how much snow will pile up.
According to the FOX Forecast Center, the rain and snow will be beneficial for the drought across the Northwest region. Portions of the Cascades are in severe to extreme drought, and portions of eastern Washington, northern Idaho and western Montana are under extreme and exceptional drought conditions.
Meanwhile, the storm is also expected to bring 20-foot waves to parts of the coast. The National Weather Service offices in Portland, Oregon, and Eureka, California, have issued a few High Surf Advisories calling for large breaking waves of 21-24 feet in the surf zone.
The FOX Forecast Center is tracking a busy head start to the rainy season as a wet pattern looks to take hold of the region for several weeks. NOAA’s Climate Prediction Center has forecast above-average precipitation for the Pacific Northwest over the next month.
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