The danger of avalanches: Will 2021 be the worst year ever?

The danger of avalanches
The danger of avalanches 06:48

Mountain mornings above Ketchum, Idaho often begin with cannon fire. The enemy? Avalanches. The Sun Valley Ski Patrol uses explosives to test the snowpack on the mountainside. It's one way Scooter Gardner, head of snow safety for the resort, keeps his guests safe.

"Our ultimate goal is to give the skiing customer as much skiable terrain as possible, that is as safe as possible," Gardner told correspondent Serena Altschul.

To the blissfully unaware, it might seem like overkill. But beyond the boundaries of America's ski resorts, the threat from avalanches is a very real part of mountain life. 

Last month snowmobilers got caught in an avalanche in Utah:

"All the snow is, is a horizontal representation of the season's weather," said backcountry guide Chris Marshall.

To really understand the danger of snowpack on a steep slope, you have to dig a little deeper.

Since the start of the pandemic, enrollment at avalanche classes by Sun Valley Guides has more than doubled with people looking to safely get away into America's wild and rugged backcountry.

Marshall walks students the basics of search and rescue, terrain management, and – critically – how to "read" the layers of snow like a geologist reads sediment. "The more readily this slides off, that's going to show poor bonding between those layers," he said, slicing into the snowpack.

"When you've got snow that looks like sugar, and especially when you can see the individual crystals with your naked eye, these are facets."

A lesson in snowpack physics by guide Chris Marshall. CBS News

Snow scientists say climate change has heightened avalanche risk. Throughout much of the West there was heavy Fall snow followed by drought. That formed a weak layer which was then buried under several feet of snow – prime conditions for the most dangerous type of avalanche, what is called a slab avalanche. Bruce Tremper, who was the head of the Utah Avalanche Center for some 30 years before retiring in 2015, described a slab avalanche as like "a cohesive plate of snow, like a magazine sliding off of an inclined table."

"Ninety-three percent of the time, that avalanche is triggered by the victim or somebody in the victim's party," Tremper said. "It means we have a choice. We can avoid avalanches if we want to by not triggering avalanches."

In 1977, as a young member of the Ski Patrol at Bridger Bowl in Montana, Tremper was warned to stay off of a slope that was a notorious avalanche path … not that he listened.

"And the first thing that happens, it feels like somebody pulls out the rug from underneath me, and I flop down on the snow and it just pulled me downhill," he recalled.

Tremper credits managing to grab a tree with saving his life.

"And I just felt like I was underneath this huge waterfall getting pounded to death. I was just tumbling down the slope, going head over heels and all over the place. Hat, mittens gone, skis gone. I mean, snow is going everywhere, down my underwear, under my eyelids. And when it came to a stop, I was buried up to my chest."

When snow is moving down a slope, it often feels like water. But when it comes to rest, it tends to set like concrete. Had Tremper been fully buried, he might have had only about 15 minutes to live.

Ethan Greene, director of the Colorado Avalanche Information Center, said, "One of the really important misconceptions is that you can dig yourself out if you get buried. And just because of how the avalanche flows when you get buried, the snow compacts – it's really, really hard."

In Western states this winter's weather has produced snowpack conditions that are making avalanches even more threatening than usual. CBS News

Of current snow conditions, Greene said, "It certainly is going to be one of the worst years in a long time. I'm hoping it's not going to be the worst year."

In fact, the week of January 30 was the worst week for avalanche fatalities in the U.S. since 1910, with 15 dead. And the season is far from over.

Greene said, "You know, it's a pretty amazing natural hazard in that you have a person that goes across a snow slope and can release maybe thousands of tons of debris that goes rolling down the hill. One of the accidents we had this last week, the avalanche itself, the break in the snow was over 3,000 feet wide. And that's triggered by a person."

That sort of risk-taking can now have legal consequences: In Colorado, two snowboarders are facing reckless endangerment charges for causing an avalanche above I-70.

Altschul asked, "If there's a high avalanche risk, do you generally shut down public lands?"

"Typically, we don't do that," Greene replied. "Part of our culture in the United States, and certainly the western United States, has a high degree of value on freedom and personal responsibility. So, these are our public lands. They're there for everybody to enjoy. And that's a wonderful thing for all of us to have access to.

And with that freedom to use those lands comes the responsibility to take care of ourselves and then also take care of the other people in our communities."

So, viewer beware: If you're pushing the boundaries, you're on your own...

Altschul asked Tremper, "What are the best ways to survive an avalanche?"

"It's kind of like asking, 'What do I do if I get in a car wreck,' you know?" Tremper replied. "And the answer is, there's not much you can do because, you know, these things are really, really dangerous. And by the time you've triggered that avalanche, you've already made all the mistakes."

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Story produced by Anthony Laudato. Editor: David Bhagat.