Slide Science

Montana researchers dig into avalanche mechanics



In early January, Justin Steck found himself buried up to his armpits after an avalanche swept him 800 vertical feet down a backcountry run in Glacier National Park. His head was bleeding, and he would later discover he had a broken arm and six broken ribs.

But the 34-year-old Missoula man is alive, and Steck is grateful for that.

Steck dropped into a run in an oft-skied area of the park dubbed "The Backstrap." He and a buddy had skied the same line the day before, though not from as high a start. Steck paused after a couple of turns. Then he heard a rustling coming from behind.

"I felt a ton of pressure, and knew I was falling," Steck says.

The slide had broken above him, and Steck was swept up in its path. The avalanche carried Steck through a stand of trees, and eventually deposited him upright with his face and one arm exposed. He remained there as the snow's hostage until his friend rode down to dig him out. Steck's friend had also been in the slide path, but managed to ride to safety.


"I'm very lucky to be alive," Steck says. He also says it's remarkable he wasn't more severely injured.

Though it's probably not in his plans to ski again this season, Steck says the harrowing experience hasn't deterred him from eventually hopping back onto the slopes again when his body does fully recover.


Lurking behind the blissful joy of backcountry skiing is the ever-present risk of avalanche danger. Every skier mitigates avalanche risk in a different way. Most will probably cruise through a formal course covering avalanche basicsa series of classes blandly dubbed AVI-1, AVI-2 and so forth. Others will learn from more experienced skiers.

A healthy portion of backcountry travelers will also assess conditions ahead of time by checking avalanche advisories. Missoula Avalanche is the local backcountry bulletin service, whose advisories are run by a team of three forecasters. Steve Karkanen is at the head of that group, and for him, getting backcountry skiers though an avalanche awareness course is just as important as getting them to check current slide conditions.

Despite the gamut of cautionary measures one can take, there is no de facto formula for staying safe in the backcountry. There remains too much uncertainty about how and why slides occur to ski risk-free 100 percent of the time.

But in Montana, one group of Bozeman-based researchers is at the nexus of where backcountry experience meets hard science. For Montana State University engineering professor Ed Adams and his "snow pack" of graduate students, understanding the relationship between snow and environment is helping them to better identify the specific conditions that grease the gears for avalanche activity.

Between Adams' research and Karkanen's advisories, the hope is that backcountry skiers like Steck can rely on solid information more than luck to avoid future catastrophes.


Ed Adams has been in the snow business for over 30 years, and skiing definitely came before engineering.

Research by Ed Adams, above, and other scientists at the Subzero Science and Engineering Research Facility at Montana State University is helping to better understand avalanches like the one that trapped Justin Steck, below, last month in Glacier National Park. - PHOTO BY  YOGESH SIMPSON
  • Photo by Yogesh Simpson
  • Research by Ed Adams, above, and other scientists at the Subzero Science and Engineering Research Facility at Montana State University is helping to better understand avalanches like the one that trapped Justin Steck, below, last month in Glacier National Park.

"My first bachelor's degree was in English. I was ski bumming down in Utah—bartending, waiting tables, that stuff—and I ran into some people who suggested that I go back and get a science degree if I really wanted to play in the snow," Adams says. He completed a second bachelor's degree in earth sciences and geophysics and has been studying snow and ice ever since.

Adams fits the profile of someone who has spent a lot of time outdoors. Ice-blue eyes stare from a weathered face tanned by countless days in the snow-reflected sun. His tall, athletic frame lives up to what his graduate students say about his skiing: The guy can rip. When asked about his skiing, Adams shrugs off the question by acknowledging how fortunate he is to get into the field so much for his work.

Early in Adams' career, avalanche studies involved experimental methods not for the faint of heart. Imagine a small outhouse-sized shack fasted to a pristine white snow face between 30 and 45 degrees. Throw some dynamite into the mix. Now imagine Adams in that shack as the avalanche lets loose. The thought was, what better way to study an avalanche than from the perspective of its slide path?

"We don't really do that anymore," Adams chuckles.

The Subzero Science and Engineering Research Facility at Montana State University is worlds apart from Adams' early avalanche studies. In the lab, scientists can simulate almost any kind of weather found in nature by controlling the temperature, humidity, radiation and other wintery factors. Several lab chambers can even simulate varying degrees of cloud cover. The lab also has an array of measuring equipment, including a CT scanner—yes, the same device doctors use to look at your brain—to observe the intricacies of a snow sample.

A typical experiment involves creating or "farming" snow on an inventive contraption designed in-house. The apparatus blows cold air and moisture over a column of strings, there to catalyze the condensation of snow nuclei. When the man-made snow falls into a bucket below, researchers have their base material. The process is representative of how snow forms in the atmosphere.

With the farmed snow, Adams and his students simulate snowpacks seen in the outdoors, complete with different layers and snow consistencies that result from varying weather conditions. The structural engineering side of avalanche science comes into play when these snowpacks are tested under pressure. The goal is to determine which environmental conditions cause the structural changes that make snow weak and prone to sliding.

David Walters is one of Adams' doctoral students at the Subzero Lab who studies a particular kind of snow change called radiation recrystallization. Walters came to the program from a background in ski patrolling, and his experience in the backcountry has helped steer his research in the lab.

Radiation recrystallization can best be described through a hypothetical scenario. Imagine you've had some bluebird days in the backcountry, but things are getting tracked out and you haven't floated on powder for a while. You do a snow dance. A couple of inches fall, but it's still too sunny and warm for the real goods. You dance harder. And then the big one touches down: 22 inches of snow overnight. Whereas you immediately imagine face shots of powder and shredding freshies, Walters sees something more.

  • Photo by Chad Harder

When the sun beats down on snow, it creates a temperature gradient in the snow profile, meaning some depths of snow are colder or warmer than others. In a typical scenario, the snow below the surface can actually become warmer than the surface itself. The difference in temperature is enough to change the shape of the snow crystals. Hexagonal jewel-like snowflakes morph into mini-daggers of ice in a process called radiation recrystallization, better known as surface faceting.

"This is a sneaky layer because it's so thin," Walters says as we look at a 3-D image of a snow core sample on his computer. "If I know there's been sunny weather for a while before a storm, I'll be looking for this."

Looking at a recrystallized layer up close shows a network of tenuous ice fibers loosely bonded together in a haphazard form overtop denser snow and ice crystals. The uppermost part of the core sample is the most porous, which makes it structurally weak.

This change is nothing to fuss over if it stays on the surface of a snowpack. But if another couple of inches of snow falls on top of it, avalanche-savvy skiers will be on the lookout for signs of unstable snow. This weak layer, now buried, suddenly has a lot more weight to support, which can put its breaking strength to the test.

Radiation recrystallization was once thought to be mostly prevalent in Colorado and Utah's high Rocky Mountains where solar radiation is traditionally more intense. Input from the local ski community, combined with Adams' interest in the phenomena, literally brought it under the microscope at the Subzero Lab.

"I think we've really established that [radiation recrystallization] is much more common in [Montana]," Adams says.

Unfortunately, identifying the phenomena is not as simple as our hypothetical scenario, where a formula of conditions creates a weak layer.

"How do you incorporate all the right inputs, and which are the most important parameters?" Adams asks. "That's where the real research is—trying to put into context what the governing concepts for radiation recrystallization are."

Radiation recrystallization is hardly the only snow metamorphism being studied at the Subzero Lab. The researchers are also unraveling the mechanics of surface hoar and depth hoar, two other weak layers familiar to backcountry skiers under the Big Sky. Overall, the lab's capabilities make it unlike any other in the world, and it attracts visiting snow scientists from countries like Switzerland, France and Japan.


It's one thing to understand how snow shape-shifts in a lab, but transferring that knowledge to the field is an equally important component of research at the Subzero Lab.

Snowpack modeling is a growing avenue for making snow science available to those who use it on the ground—namely ski patrollers and avalanche forecasters.

"We take a digital elevation map," Adams explains, "and we digitize everything. We add vegetation, like trees, and we add snow in there and how the shadows are cast."

By calculating for a known set of variables, Adams can follow the energy transfer and subsequently see how snow might change in a way that can compromise its structural stability.

The use of models for predicting landscape conditions is widely used in fire science. Wildland fire managers use models that account for wind, humidity and fuel type to predict how fire moves across a landscape. Adams hopes snowpack modeling is headed in the same direction.

"Running these models you can actually see what's happening, you can see the temperatures changing across the snow," Adams says.

This kind of technology has the potential to be very useful for avalanche forecasters.

Technology aside, Adams' intricate understanding of snow structure makes him somewhat of a human avalanche model.

"Once you start looking at all the conditions that can change snow, you begin to process what goes on and build them into the little computer in your head," Adams says.

That sort of processing is intrinsic to skiers with countless hours logged in the backcountry. Over time, some develop an uncalculated feel for what's going on with the snow.


Steve Karkanen is another one of those human avalanche models. But in Karkanen's defense, he also uses a multitude of physical tools to do his work.

Karkanen is the director of the West Central Montana Avalanche Center, a nonprofit avalanche advisory service funded by the Forest Service and by private donations. The group is better known as Missoula Avalanche, locally famous for their avalanche awareness courses and Kettlehouse fundraisers.

David Walters “farms” snow in the Subzero Lab. - PHOTO BY  YOGESH SIMPSON
  • Photo by Yogesh Simpson
  • David Walters “farms” snow in the Subzero Lab.

Three forecasters prepare backcountry advisories for west-central Montana, and Karkanen brings 21 years of professional ski patroller experience to the head of the table.

"We're looking for a lot of things, not just the quality of the snow, but also its history," Karkanen says. "We're looking at what's happened with the weather the past few days and what's going to happen with the weather."

If snow is like clay, then the environment is its sculptor. Karkanen and his colleagues watch the alpine snowpacks as early as October to get an idea of how base layers are shaping up for the season. They watch the weather to gauge probable snowpack conditions. But just as importantly, the forecasters head into the backcountry, digging snow pits and physically testing snowpack stability for Missoula Avalanche's bi-weekly advisories.

The bulletins—posted every Monday and Thursday—reflect the general conditions in the backcountry ranging from down in the Bitterroot all the way north through the southern Swan and Mission mountains. Describing the variability of the snowpack over a broad area is a challenge.

"It's not easy to come up with a report at 4 or 5 in the morning when you've got multiple different types of weather in different areas of our advisory," Karkanen says.

For example, last winter's snowpack was marked by a layer of depth hoar, an unstable layer that has a sugary consistency that doesn't bind well to other layers. Think of it as the type of snow that's useless for making snowballs.

"We had up to 70 centimeters of depth hoar," Karkanen says about last season's snowpack. That layer came from a November snow dump followed by spring-like conditions without much new snowfall. The risk was recognized early on, and a mention of the depth hoar layer consistently made it into the avalanche bulletin.

Those bulletins are becoming increasingly well read. Missoula Avalanche's website received over 34,000 hits last seasona 14-percent rise in traffic over the previous winter. Karkanen says the spike is the result of more people recreating in the backcountry now than when he first started monitoring snow conditions.

With more backcountry skiers, Karkanen stresses another key component of Missoula Avalanche. He says avalanche education has become the most important part of his group's work.

"We're seeing more and more young people accessing backcountry terrain without transceivers, or even a basic knowledge of what they're getting into," Karkanen says. "We're trying to bridge that gap."

In general, Karkanen feels like there's been positive growth of avalanche awareness in western Montana. "We've hit the backcountry ski and snowboard community pretty hard—I feel like we're making an impact," he says. "The number of fatalities speaks for itself. We haven't had very many fatalities yet the use has increased dramatically compared to what it was 10 years ago."

Snowmobilers, though, are a group Karkanen says the group has struggled to connect with. Avalanche statistics support that concern: Of Montana's six avalanche fatalities last winter, four involved snowmobilers, according to the Colorado Avalanche Information Center, the national record-keeping group of avalanche statistics.

Nationwide, last winter was one of the most lethal in recent history. Of the season's 34 avalanche fatalities, six of those were in Montana. This year, avalanches across the United States have claimed nine lives so far. None have occurred in the Treasure State.


Posting accurate and timely avalanche advisories is made complicated by the fact that snow is constantly changing and shifting its shape. Weak layers in the snow can actually heal their own structural shortcomings under the right conditions. This sort of shape-shifting can be positive for skiers, and it's another genre of snow metamorphism on the minds of researchers at the Subzero Lab.

Last winter's layer of depth hoar kept Karkanen's attention for most of the season because of its persistence, but not every weak layer remains so dangerous for so long.

"Even if depth hoar does form, when you get a couple more feet of snow on top of it, it tends to heal itself, or it slides and the layer goes away," David Walters says. "If you're able to load the snowpack in a slow enough fashion, it can slowly heal itself. One of the major factors for getting snow to slide is not only the amount of load on a weak layer, but how fast it was loaded.

"If you get two inches a day for three weeks," he continues, "that's a lot better for stability than if you get that same amount of snow in a 24-hour period."

Karkanen says the work that goes on in the Subzero Lab has positively impacted Montana's avalanche forecasting community by highlighting the science side of what is happening in the field. Some of the lab's work has specifically improved his own forecasting methods.

Likewise, Walters and Adams both agree that the Subzero Lab's relationship with ski patrollers in the field is a major asset to their research.

Steve Karkanen, director of the West Central Montana Avalanche Foundation, heads into the field to check backcountry snow conditions. - PHOTO BY CHAD HARDER
  • Photo by Chad Harder
  • Steve Karkanen, director of the West Central Montana Avalanche Foundation, heads into the field to check backcountry snow conditions.

"Relationships with surrounding ski patrollers are necessary for our work here," Adams says.

The Subzero Lab regularly collaborates with the snow staff at Yellowstone Club, Moonlight Basin, Big Sky and Bridger Bowl.

"If we see something in the field that we've been working on in the lab, we're eager to share that information and usually invite any of the patrollers over for a closer look at it," Walters says.


The day Justin Steck found himself partially buried in the avalanche in Glacier National Park, he wasn't wearing a beacon. Steck says he's never used one in the roughly seven years he's been a backcountry skier. But he was wearing a helmet, which was found shattered into pieces near where Steck was found in the slide path. He has no doubt the helmet saved his life.

Just more than a month after the accident, Steck is still recovering. Daily tasks often prove difficult or frustrating, like when he's unable to twist open the lid of creamer to pour into his coffee. "I feel like I'm on the outside, looking in at my injured self," he says, almost as if it's still a surprise to notice his broken arm.

With regard to his future in the backcountry, Steck says he plans to cover the bases more diligently. "I plan on having a beacon, I plan on taking a class," he says. "Several great skiers have died in avalanches doing all the right things, so there's no guarantee. But since the possibility is death, I'd like to do what I can to mitigate the risk."

In Montana, that means he'll probably end up benefiting from improvements in snow science flowing from the Subzero Lab, and Steck will maybe even sit in on one of Karkanen's classes.

This story was updated Friday, Feb. 22, to correct last season's depth hoar figures.

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