- A flood watch is in effect for more than five million people in Washington and Oregon.
- An avalanche warning is also in effect for the Washington Mountains.
- “A major positive from this event will be substantial rain falling over far eastern Washington.”
An “extreme” atmospheric river was pouring into the Pacific Northwest on Monday, and with it will come the threat of flooding and avalanches, forecasters said.
“It will be an active period of days across the North West as we leave February in the rearview mirror and begin March,” said AccuWeather meteorologist Alex DaSilva. “A parade of storms will keep the weather active in the northwest through Wednesday.”
Meteorologists said rain amounts will range from 2 to 4 inches early this week from Portland, Oregon, to Seattle, and locally higher amounts are possible on the windward sides of the mountains.
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A flood watch is in effect for more than 5 million people in Washington and Oregon, the National Weather Service said. This includes the Seattle and Tacoma metropolitan areas. “Inundation of rivers, streams, creeks and other low, flood-prone places” was possible, the weather service said.
An avalanche warning is also in effect for the Washington Mountains, and “very dangerous avalanche conditions” are expected, according to the Northwest Avalanche Center in Seattle.
“Avalanches can get very large and destructive,” the center said, adding, “Avalanches will be large enough to bury you or kill you, and it won’t be a day to try and outmaneuver danger.”
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Bad weather is courtesy of an “atmospheric river,” a ribbon of water vapor that can stretch for thousands of miles from the tropics to the western United States. Between 250 and 375 miles wide, the River of Moisture provides fuel for massive rains and snowstorms that can cause flooding along the West Coast.
“Some people rate atmospheric rivers as hurricanes and tornadoes, and they classify this event as an AR4 (atmospheric river, category 4) out of a possible 5,” Seattle-based meteorologist Cliff Mass said on his blog on Sunday.
The news wasn’t all bad, however: “A major positive from this event will be substantial rain falling over far eastern Washington, helping to restore soil moisture for dryland farmers there. “Mass said. “The strength and direction of this atmospheric river is well structured to bring moisture to eastern Washington. Very good news.”
Indeed, the heavy rains come from a relatively dry start to February, according to CNN. As of Sunday morning, Seattle-Tacoma Airport had received just over 1 inch of rain this month, which is a deficit of more than 2.5 inches for the month of February, CNN said. .