Get ready for action in Montana as the Flathead Avalanche Center issued an avalanche watch on Monday night due to an atmospheric river sweeping the northwest.
The ongoing storm has been soaking the Pacific Northwest since the weekend and now, as it moves east, Montana residents are being warned by weather officials. The stormy weather could trigger an avalanche in various parts of the state.
An atmospheric river, described as a “long, narrow region in the atmosphere—like rivers in the sky— that transport most of the water vapor outside of the tropics,” by the National Oceanic and Atmospheric Administration (NOAA), is behind the watch. California dealt with over a dozen similar storms last winter, cruising out of a drought but bringing flooding and mudslides.
The backcountry avalanche watch was issued for Flathead County, Lake County, and Lincoln County, with the risk anticipated to increase by Tuesday morning as the atmospheric river arrives.
Mist rises above ice on the Yellowstone River on December 22, 2022, in Paradise Valley, Montana. Flathead Avalanche Center issued an avalanche watch for parts of Montana through Tuesday night.
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“If the storm develops as forecasted, rain on snow will increase the likelihood and size of triggered and natural avalanches,” the report said.
Newsweek reached out to the Flathead Avalanche Center by phone for comment.
The areas most at risk were the steep mountain slopes above 5,000 feet high in the Whitefish Range, Swan Range, Flathead Range, and the John F. Stevens Canyon, the Apgar Range, and the Marisas Pass in Glacier National Park.
Avalanches, or a rapid flow of snow down a hill or mountainside, kill more than 150 people globally each year, according to the National Weather Service (NWS). They can be caused by a variety of different factors, including heavy snow cover, a particularly steep gradient, and the climate.
The watch will remain in effect through Tuesday night.
“Rain on snow may overload the snow surface and buried weak layers resulting in widespread areas of unstable snow and natural avalanches,” the report said. “Very dangerous avalanche conditions are expected to develop. Travel in avalanche terrain will become increasingly dangerous. Avalanches may run long distances and into areas with barren ground.”
The NWS office in Missoula also warned of other impacts from the incoming storm.
“Mild and wet conditions are expected through Wednesday. The bulk of precipitation will fall in northern Idaho and northwest Montana near the Idaho border,” NWS Missoula posted on X, formerly Twitter, on Monday. “Rain and melting snow will lead to possible ponding of water.”
NWS meteorologist Joe Messina told Newsweek that the atmospheric river arrived overnight and is forecast to raise temperatures today. The temperature forecast high for Tuesday is 52 degrees, a 19-degree jump above the state’s average this time of year.
“Our record is 50 degrees,” Messina said.