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To determine the risk of avalanches, avalanche experts perform a snow stability test



Bozeman, Montana — This year’s winter weather has been particularly harsh in Montana. Avalanche forecasters have been on edge as it pertains to the stability of the snow in Montana’s backcountry due to the amount of mountain snow, the strength of the winds, and the icy temperatures. Nine avalanche fatalities have been reported around the country as of February 23. On New Year’s Eve in Cooke City, Montana, one of the fatalities included a snowmobiler. Sadly, the snow still has some weak layers that are raising questions.

The best method for determining whether the snow is unstable is to dig a hole and conduct a stability test. Daily stability tests in avalanche terrain are conducted by the Gallatin National Forest Avalanche Center (GNFAC) by digging deep into the snow. “As an avalanche forecaster and an avalanche center, we are giving a regional perspective,” the director of GNFAC told MTN News. “We are painting the avalanche danger with a pretty thick brush.”

They cannot possibly cover every slope in a region that extends from the Bridger Range to the south of West Yellowstone. In order to evaluate a slope’s stability or assess whether it is growing more or less stable, they attempt to strike slopes that are unknown or that people are using for recreation. Yet if you want to be secure, you can’t only rely on that knowledge. “When you go out if you are a skier or a snowmobiler, and you are heading to a specific slope and you want to know, will this specific slope avalanche or not, the onus is going to be on you to figure out if that slope is safe or not.” Chabot said.

If there is no sign of recent avalanches, the easiest technique to determine whether snow is unstable is to dig a pit and conduct a stability test. “People say, ‘oh my god, I don’t want to dig down, it’s going to take a lot of time’” Chabot said. “But it doesn’t take a lot of time.”

Chabot completed an avalanche assessment using the so-called Extended Column Test in less than 5 minutes (ECT). This involved excavating a trench, separating a 90 by 30 cm rectangle of snow, and tapping the snow repeatedly with his hand and shovel. The test is not difficult. “I start with ten taps from the wrist, if I don’t get anything then I get ten taps from the elbow, and if I still don’t get anything, I’ll get ten taps from the shoulder” Chabot clarified. These taps demonstrate the amount of force required to determine whether a slab of snow fails and whether the crack spreads, which is one of the key conditions for an avalanche to happen.

The video demonstrates the unstable terrain we were investigating, which has been a typical occurrence on many of Montana’s slopes this winter. It does, however, imply that you must be aware of the landscape and that people shouldn’t go outside in avalanche terrain. The weight of a skier or snowmobile won’t typically impact the snow deeper than that on any particular slope, according to Doug, thus a pit doesn’t typically need to be deeper than 3 or 4 feet.

The GNFAC advises people to visit to view the avalanche report for their particular area if they do decide to venture outside. Also, their website offers immediate access to additional safety and online tutorial information.

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