Avalanche warnings have been issued for parts of Washington and Oregon as heavy rain and snowfall will affect part of the West Coast from Monday.
The warning was issued on Saturday by the Northwest Avalanche Center, which said at least 30 people had died in the United States so far this season. It is the deadliest since the 2015–16 season according to the center.
The warning, a level 4 on a scale of 5, said there was a high avalanche threat to parts of the North Cascades National Park from the Canadian border, extending south through the Okanogan-Wenatche National Forest and some of the Giffe Pinchot National Forest In parts, which is about 140 miles southeast of Seattle.
The warning is in effect until Sunday evening and includes part of Mount Hood National Forest, about 70 miles east of Portland, Ore.
The center’s warning hung for heavy-to-normal rainfall in parts of the Pacific Northwest “Atmospheric river,” the National Weather Service said on Twitter.
This type of weather event – “a long river of moisture” that can hover over concentrated areas for a period of time – is prone to very heavy rain or intense snowfall at high altitudes, meteorologists at the Meteorological Service in Seattle . .
The National Oceanic and Atmospheric Administration called such events “rivers in the sky”. The meteorologist for the meteorological service, Dustin Guy, said this one extends about 3,000 miles off the coast of British Columbia, to the coast of Hawaii.
Another meteorological department expert, Matthew Cullen, said Seattle could only receive half an inch of rain, with coastal areas and mountainous areas expected up to three inches. He said that at high places like the Cascade Mountains, one to two feet of snow could fall in altitudes higher than 4,000 feet above sea level.
Mr. Kalan said that a handful of atmospheric rivers hit the region in all seasons and it was moderate in terms of rainfall and duration so far. Nevertheless, it is coming into the area especially soon after intense snowfall.
He said Seattle had about half an inch of snow in December and January. Then, about 12.5 inches of snow fell over a three-day period ending on 14 February.
“There were just several hours of continuous snow on the order of about an inch,” recalled Mr. Cullen.
Americans have recently seen what deadly, record-low temperatures can do. Last week the blanketed winter storms from the south and central United States stalled energy supplies in Texas and left millions without adequate heat and water supplies.
According to the avalanche center, weather conditions on Sunday will make travel in the avalanche area dangerous.
“Heavy snow, wind and rain will load the snowpack fast and create large natural avalanches,” said Andrew Keffer, a center official, in a forecast. “The very dangerous situation will continue from Monday.”
“The avalanche threat will peak Sunday night,” the warning states. “There is a possibility of large natural avalanches within the new ice, especially in the air-filled areas at upper elevations.”
According to the center, both a snowmobiler in Wyoming and a backcountry skier in Colorado died in separate avalanches.
The following day, two backcount skiers in Colorado were killed in an avalanche. The most recent death occurred near Sherman Peak in Idaho, when a snowmobiler died on Saturday.