An avalanche warning has been issued for parts of Washington and Oregon, as heavier rainfall and snow are expected to hit part of the West Coast by Monday.
The warning was issued Saturday by the Northwest Avalanche Center, which said at least thirty people in the United States have died in avalanches so far this season. According to the center, this is the highest number of deaths since the 2015-16 season.
The warning, a level 4 on a scale of 5, said there was a major avalanche danger for parts of the North Cascades National Park at the Canadian border, which stretches south through the Okanogan-Wenatchee National Forest and to portions of the Gifford Pinchot National Forest, which is about 140 miles southeast of Seattle.
The warning is effective until Sunday night and also covers part of the Mount Hood National Forest, which is about 70 miles east of Portland, Ore.
The warning from the center came when parts of the Northwest plagued the Pacific Ocean for heavier-than-usual precipitation due to a “Atmospheric river”, the national weather service said on Twitter.
These types of weather conditions – a ‘long humid river’ that can hover over concentrated areas for a period of time – are expected to lead to very heavy rainfall or, at higher altitudes, intense snowfall, meteorologists at the Weather Service in Seattle said. .
The National Oceanic and Atmospheric Administration described events as ‘rivers in the air’. This one stretches about 3,000 miles, from the coast of British Columbia to the coast of Hawaii, said Dustin Guy, a meteorologist from the Weather Service.
Although Seattle may only be about half an inch of rain, coastal areas and mountainous areas can expect up to three inches, another weather service Weather Service spokesman Matthew Cullen said. In high places, such as the Cascade Mountains, one to two feet of snow can fall at altitudes above 4,000 feet, he said.
A handful of atmospheric rivers have hit the area each season, and this one is expected to be moderate so far in terms of precipitation and duration, said Mr. Cullen said. Yet it comes to the region shortly after a particularly intense snowfall.
A total of about an inch of snow fell in Seattle in December and January, he said. Then almost three inches of snow fell over a period of three days ending on February 14th.
“There was definitely a few hours of regular snowfall of about an inch per hour,” said Mr. Cullen remembers.
Americans have seen very recently what deadly, record low temperatures can do. A stormy winter storm that dominated parts of the southern and central United States last week has strained energy supplies in Texas, leaving millions without adequate heat and water supplies.
According to the avalanche center, the weather conditions on Sunday will make it dangerous to travel in avalanche sites.
“Heavy snow, wind and rain will quickly load the snowpack and deliver large natural avalanches,” center Andrew Kiefer warned in a forecast. “Very dangerous conditions will continue until Monday.”
“The avalanche danger is likely to peak on Sunday night,” the warning said. “Large natural avalanches in new snow are likely, especially in wind-laden areas at upper altitudes.”
A snowmobile in Wyoming and a skier overseas in Colorado died in separate avalanches on Dec. 18, according to the center.
The next day, two skiers in the state of Colorado died in avalanches. The latest death was near Sherman Peak in Idaho, when a snowmobile died Saturday.