BOISE, Idaho– As a massive winter storm dumped snow on much of the western US, winter sports enthusiasts flocked to ski resorts and backcountry slopes ahead of the long Martin Luther King Jr. Day weekend.
But in many areas the storm, together with the wind and snow, brought a high avalanche risk, with fatal consequences.
In northern Idaho, two men were rescued and a third was believed dead after being caught in an avalanche Thursday afternoon. Later that night, the occupants of two vehicles escaped without injury after an avalanche buried their cars in another part of the state.
The first reported U.S. avalanche death of the season occurred Wednesday morning in California, on a section of expert trails at the Palisades Tahoe Ski Area near Lake Tahoe. Four people were trapped and one died in the slide. The next day, a second avalanche struck the same area, causing no casualties.
Here’s why, when and how avalanches occur, and some tips on how to protect yourself from slides:
It generally only takes two ingredients to create avalanche conditions: a slope of 30 degrees or more and layers of snow.
“Avalanches are actually connected to layers in the snowpack, and those layers are caused by weather events,” said Ben Bernall, avalanche forecaster with the US Forest Service Panhandle Avalanche Center. “It’s a bit like a cake: you might have a nice thick layer that’s nice and cohesive, and then a thinner layer of frosting. Then place another cake on top, and add the factor of slope or steep terrain.”
Extra pressure on top of that snow cake, from wind, rain, heavy snow or movement, can cause some layers to shear and slide down the slope, Bernall said.
Sometimes this sliding takes place in the form of loose snow, a so-called ‘sluff’. According to the Sierra Avalanche Center, mudslides are responsible for only a small percentage of deaths and property damage from avalanches.
But many avalanches consist of slabs, where a large layer of snow breaks loose and slides down the mountainside. These are responsible for most fatalities.
Another type of avalanche occurs when the wind creates a cornice of snow hanging over a ridge or the edge of a steep slope. According to the Colorado Avalanche Information Center, an overhanging mass of snow can suddenly fall, surprising anyone standing under or on top of the cornice.
Movement, rapidly changing weather, wind: all these things can cause an avalanche. But experts say 90% of avalanches that cause injuries or deaths are caused by the victim or someone with them.
That means people skiing, snowmobiling, snowshoeing or doing other activities in the snowy backcountry should check the avalanche forecast before heading out and make sure they have the proper safety equipment.
Most ski areas have avalanche protocols or mitigation systems. This often means checking the stability of the snow cover. Avalanche experts and ski areas also sometimes use remote detonations to manually activate slides, removing the riskier layers of snow before skiers are allowed onto the slopes.
Generally loud noises. Despite what cartoons and movies might have you believe, the sound waves from someone shouting aren’t enough to cause an avalanche, according to the Sierra Avalanche Center.
However, in particularly unstable snow conditions, an extremely loud noise, for example from a nearby explosion, can provide a solution.
According to the Federal Emergency Management Agency, an average of about 28 people die each year from avalanches in the U.S. Last winter, thirty people were killed by avalanches in the United States. All were skiers, snowboarders, snowmobilers, snowshoers, climbers or hikers, according to the Colorado Avalanche Information Center.
Last February, three members of a New York mountain climbing club were killed in an avalanche on a remote mountain peak in Washington state’s Cascade Mountains.
Three climbers in Alaska’s Denali National Park were killed in two separate incidents on the same day in May. One caused an avalanche while skiing in the park’s backcountry. Two others were swept away as they prepared to climb a peak known as Moose’s Tooth. Their bodies were never found.
There are several ways to avoid an avalanche, but running is not one of them. According to the Sierra Avalanche Center, dry avalanches typically reach speeds between 60 and 80 miles per hour (between 96 and 129 km/h) within seconds of starting. Wet avalanches usually travel around 20 miles per hour (32 km per hour).
By comparison, eight-time Olympic gold medalist Usain Bolt achieved a record speed of just under 28 miles per hour (45 km/h) in the 100-meter sprint in 2009 – and that was on a flat track, not a swirling snowstorm. covered slope. Experts say most people caught in an avalanche are on the slope when the slide occurs.
A better plan is to avoid the avalanche before it happens. Recreationalists can consult avalanche forecasts at their regional avalanche center or at www.avalanche.org. Experts say backcountry users should also learn and watch for the signs of avalanche terrain and unstable snow, and avoid cornices and high-risk areas.
Bernall said three pieces of equipment are essential for anyone in avalanche country: an avalanche transceiver, which sends a location signal to other people in the group if one person is buried; a shovel to test the snow cover and dig out any buried companions; and a thin, collapsible avalanche pole that you can use to reach into the snow to find someone buried by the snow.
It’s also a good idea to use the buddy system, Bernall said, and to be versed in first aid and wilderness rescue skills.
“Good decision-making in the backcountry is the biggest piece of the puzzle,” he said. “With the right decision-making, everything else is kind of obsolete.”
This weekend, the best bet in central Idaho’s avalanche country is to stay at lower elevations and away from steep slopes, Boise County Sheriff Scott Turner said.
“People have been waiting for snow to come again, but snow conditions are not good at the moment. We encourage people to stay on lower ground,” Turner said.