Deadly inbounds avalanche at Silver Mountain highlights danger, complexity of mountains

Wardner Peak, the site of a Tuesday avalanche that killed two people and injured five more, is a 6,200-foot feature on the western edge of Idaho’s Silver Mountain resort.

It offers a unique attraction: an inbounds peak that is not accessed by a chairlift, yet is still patrolled and managed by the resort.

Skiers and snowboarders ride Chair 4 to its terminus and traverse along a ridge, the aptly named Wardner Peak Traverse. Once they gain the peak, they access a handful of steep runs high above the Silver Valley. It’s not a far hike and doesn’t require specialized gear. However, the extra effort, combined with the steeper and more challenging terrain, keeps many away.

Like elsewhere, the area is patrolled and the avalanche risk is managed. In the mornings, before the mountain opens, patrollers throw bombs, hoping to start slides. They also ski along the top of steep aspects, trying to trigger unstable snow below. Working in groups of two or more they cover predetermined areas known to slide. Most avalanches occur on slopes between 30 and 45 degrees.

However, as evidenced by Tuesday’s tragedy, that doesn’t always work.

Avalanches are complex and snow science is a dizzying discipline offering full-time employment for many serious scientists.

In general terms, avalanches are caused when layers of snow are not well bonded together. How and when snow bonds (or doesn’t bond) varies depending on temperature, humidity, snowfall, rainfall, geography, topography, wind, past winter conditions and other factors.

Heavy and rapid snow accumulation, as occurred at Silver Mountain and throughout the region over the past days, increases the likelihood of avalanches as the so-called “storm slab” sits on top of an older layer of snow.

While it’s easy to know when a storm slab has formed (after a big storm), the exact locations of these pockets of instability are harder to predict due to all the variables mentioned above. In avalanche forecasting lingo, this is known as “spatial variability.”

To further complicate the issue, there is another type of snow formation more difficult to manage. Known as a “persistent slab” this is a weak layer of snow buried beneath the surface. This layer doesn’t stick well to the layers above and below. It can remain unstable for a day, a week or the entire season.

Thus, avalanches tax our understanding of cause and effect.

That complexity is at odds with the image most have of ski resorts as totally safe and controlled spaces.

The reality is they are, like all mountain environments, dynamic and ever-changing. While inbounds avalanche deaths aren’t common, they aren’t unheard of.

In January 2018, two skiers were buried by an avalanche in New Mexico’s Taos Ski Valley. Both skiers died. In March of the same year, an inbounds avalanche in California’s Squaw Valley caught five people. The next day, an avalanche ripped through Mammoth, burying six resort employees.

Closer to home, three skiers were buried and quickly rescued in a small avalanche at Schweitzer Mountain Resort in 2012.

The specifics of Tuesday’s avalanche will be rehashed and blame will be, no doubt, informally assigned.

But in the past, ski resorts have been mostly shielded from litigation following inbounds slides.

In 2016, the Colorado Supreme Court ruled that avalanches are an inherent risk of skiing under the state’s Skier Safety Act. The state law doesn’t specifically mention avalanches, but does mention other possible dangers, including terrain and weather.

For comparison, Idaho’s applicable skiing law specifically mentions avalanches as a risk assumed by the skier. Meanwhile, Washington’s skiing law does not specifically mention avalanches, instead referencing the “inherent risks in the sport of skiing.”

Between 1950 and 2017, 45 skiers and snowboarders have been killed by inbounds avalanches, according to Outside. On average of about 27 Americans die in avalanches, of any type, every year. Counting Tuesday’s death, five people have been killed by avalanches in the U.S. during the 2019-20 season, according to Avalanche.org. During the 2018-19 season, 25 people died.

These are small numbers, with many more Americans dying in car accidents each year.

But those numbers may grow as global warming increases the likelihood of avalanches and as resorts open steeper and more complex terrain in response to the desires of skiers and snowboarders.

All of which makes it worth reiterating: Mountains are complex environments, ones that demand our attention and respect.

Ski with a buddy. On deep snow days, consider wearing an avalanche beacon. And above all, pay attention to terrain and changing conditions.