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Avalanche!

by Jack Kintner

One of the best things about snow is that everyone gets to go a little nuts, throwing snowballs, going tubing or getting a little goofy on skis or snowboards.

However, this glorious white stuff that makes kids out of all of us and gives us time off can also kill you – as it does to an average of 11 people each year in Canada and roughly twice that many in the U.S. Fallen snow is a highly complex material that can behave like a pile of sand or like white water, like feathers or concrete, ice cream or fresh chewing gum, and is given to unpredictably sliding away in avalanches that have killed people by ones and twos and by the thousands. The legendary amounts of snow that grace the north Cascades of Washington and the Coast Mountains of B.C. deserve to be treated with respect.

Information is readily available. For example, in Canada the statistically most common avalanche victim is a male in his late 20s triggering an avalanche while on foot or riding a snowmobile between noon and 2 p.m. sometime during January, February or March. The day is clear with little or no wind and the slide is a dry slab (powdery leading edge) less than a meter deep triggered by the victim or his party, according to the information-rich website for the Canadian Avalanche Association at www.avalanche.ca.

Accident reports on the National Oceanographic and Atmospheric Administration’s Northwest Avalanche Center web site at www.nwac.noaa.gov list two fatalities so far this year in Washington state, a skier at Alpental and a climber on Mt. Rainier caught while exploring inside a crevasse nearly 12,000 feet high on the Ingraham Glacier. Both were with partners who self-rescued and survived.
Shortly before Mt. Baker Ski Area opened this fall a snowboarder was buried near the bottom of Austin Pass, outside the ski area boundary. The snowboarder and three friends had dug a snow pit to test the snow, according to a man who said he saw the group’s mishap. After being buried by a relatively small slide, the victim was dug out alive by his friends, unconcious, choking for breath and turning blue.

Mt. Baker’s deserved reputation as one of the friendliest ski areas anywhere when it comes to snowboards and the people who ride them is also a place that takes safety and knowledge about the back country terrain so close at hand very seriously.

Rachel Vasak, director of the Mountain Education Center, teaches classes of 10 and up each weekend from January through early March in the Mt. Baker Lodge and outside on the mountain itself. A scientist by training, her approach to safe back country travel is direct without being doctrinaire, both factual and filled with vignettes that illustrate her points. Vasak’s seven-hour introductory Mountain Safety Education class will be taught January 7 and 22 and costs $25. More information and on-line registration is available at www.mtbaker.us/mec.

“Be sure your probe is long enough,” Vasak said, “because some people stop at a length of six feet to save weight and because people buried deeper than that statistically don’t have as good a chance, but I know of several people buried deeper than that who have survived.”
Time of burial is also a factor. Although victims can suffocate in minutes, statistically a victim’s chances of survival deteriorate rapidly after a half hour to less than 50 percent. However, on December 12 of last winter two women and a man snowshoed outside the Mt. Baker Ski Area boundary and up the road toward Artist’s Point. They were buried by a soft slab avalanche from the 30-35 degree slope above them as they paused at the last switchback. The next morning the man was able to make a hole in the surface with his hand and draw the attention of nearby skiers who dug him out and returned him to the lodge. A rescue party later dug out both women, the first dead and the second severely hypothermic with a core temperature of 88 degrees. Both she and the man had survived more than 24 hours, and she had been found because a prober accidentally stepped into the air pocket that kept her alive.

Vasak referred to what she called the “Avalanche Triangle” of weather, terrain and snowpack, three primary factors a back country traveler can use to help estimate the likelihood of avalanches on a given slope.

For weather, has it been unstable? Has there been a lot of recent snow, wind or rain? For the snowpack, is it unstable? Is it collapsing, cracking or hollow? For terrain, could it cause an avalanche? Where is it within the range of possibility?

“The most likely slope, the pinnacle of probability is between 35 and 40 degrees, but that expands either way with changing conditions,” Vasak explained, “and it’s not just being on a steep slope. Being next to them can be dangerous as well, because they can carry across flat terrain.”

Beacons are so light in weight and unobtrusive these days that Vasak said many wear them inside the area as well as in the back country. “The area’s as safe inside the boundaries as the ski patrol can make it,” she said, “and they’re very good. But many of us still wear beacons. And one thing it means is that we’re quickly ready to go on a rescue if the need arises.” Beacons can be rented for a little as $10 per day at several stores in the area.

Vasak uses Snow Sense by Alaska Mountain Safety Center directors Jill Fredston and Doug Fesler as part of her class. Fredston, a two-time National Outdoor Leadership School (NOLS) graduate, has also written the just-published Snowstruck about their life as avalanche rescuers and rescue trainers that ought to be required reading for anyone headed into the back country.

NOLS instructor Ian McCammon, a Ph.D. in mechanical engineering who left a career in robotics at the University of Utah to pursue snow science, has posted several abstracts at his website, www.snowpit.com. In one he describes a field method for identifying structural weakness in the snowpack based on five common characteristics of avalanche – prone slopes, the depth of the plane at which the snow will fail, the thickness of the weak layer, the difference in hardness of layers across a fracture plane, and the size and type of grains the snow has formed into.

Evaluating the snow means digging a pit into the snowpack at least a meter deep to identify weak layers in the snowpack and assess their strength, to get temperatures at different layers, especially if the snow is close to 0º (32º F), to find the progress of metamorphism or change in snow characteristics with age and to find the depth of potential slab avalanches.

Vasak’s class not only gives the tools to make these assessments but teaches a lot about the characteristics of snow, a material that varies greatly in behavior depending upon numerous physical factors – age, moisture content and so on.

It’s also the best way for those interested in back country travel to satisfy two of the requirements set by the Mt. Baker Ski Area for people who enter the back country from the ski area or return: how to use a shovel and an avalanche transceiver, knowledge of your terrain and route as well as general avalanche knowledge, and awareness of local avalanche conditions and forecast.

Once backcounty travelers build the knowledge to make as sound a decision as possible, having already assumed certain risks by being out there in the first place, McCammon recommends a simple decision framework based on the acronym ALP TRUTH:

Avalanches – were there any in the area within the past 48 hours?

Loading – what kind and how much by snow, wind or rain in the previous 48 hours?

Path – is an avalanche path identifiable by a novice.

Terrain trap – Gullies, trees, cliffs and so on that increase the severity of being caught.

Rating - “Considerable” or higher hazard on the current avalanche bulletin.

Unstable snow – Collapsing, cracking, hollow snow or other clear evidence of instability.

Thaw instability – Recent warming of the snow surface due to sun, rain or warm air.

There’s nothing for the letter H except perhaps the willing to say “Heck, no,” to a promising but risky adventure.

For McCammon, Fredston and Vasak, knowledge is the key to enjoying the rewards of back country travel. The reward is not the inherent risk but is available to those who know enough about the risks involved to minimize them.