Waves of rain will increase the flood risk in the Pacific Northwest this week as rounds of atmospheric rivers bring heavy rain, and snow to higher elevations. FOX Weather Meteorologists Bob Van Dillen and Haley Meier explain the timing for the parade of storms.
An active pattern kicks into high gear this week in the Pacific Northwest as a parade of atmospheric rivers could drop up to a foot of rain for coastal areas and several feet of snow at higher elevations.
The FOX Forecast Center is tracking a busy head start to the rainy season bringing with it flooding potential with rounds of atmospheric rivers set to arrive back-to-back in the coming week.
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.
The graphic below shows these “waves” of moisture arriving along the West Coast beginning Tuesday night and Wednesday morning. Then, they just keep coming.
A graphic showing rounds of atmospheric moisture surging into the Northwest.
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By the end of the week, some parts of Washington could see between 8 and 12 inches of rain, where more widespread areas across the Pacific Northwest could see between 5 and 8 inches.
The heaviest rainfall is forecast between Friday and Saturday.
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With so much rain comes the threat of flooding. A level 1 Flash Flood threat exists for Northern California, coastal Oregon and parts of southern coastal Washington for Friday and Saturday.
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For elevations above 5,000 feet in the Cascade Mounts, the rounds of atmospheric rivers will mean snow for the mountain passes. Snow accumulations could top up to two feet in some areas, but it’s still early to tell how much snow will fall.
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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.
