|Photo: Benji Kallman|
By John Clary Davies
Published: January 27, 2011
If you write an avalanche awareness blog, it's been about as busy as Boxing Day at Vancouver International on the Canadian storyline front. Saturday, Jan. 16, the Canadian Avalanche Centre's Avalanche Awareness Days kicked off with an inbounds slide at Fernie, from which patrol rescued seven people, none of whom sustained serious injuries.
A few days later, after continued snowfall, the CAC issued a special warning cautioning riders of the highest avalanche risk in 30 years. In the report, CAC Forecaster Karl Klassen said, "We're concerned that snowmobilers, skiers, snowshoers and even ice climbers might be at risk of being caught in these avalanches when they're not expecting them because the problem looks like it's getting better when it's just becoming more and more hidden." (Video here.)
People still went into the backcountry. A snowmobiler was killed when an avalanche struck his party near the B.C./Alberta border, becoming the fourth Canadian to die in a slide in recent weeks. An avalanche buried a snowboarder in an out-of-bounds area at Revelstoke; patrollers, nearby teaching an avalanche skills course, responded fast enough to dig out the rider in time.
The incidences prompted a number of stories. In an article headlined, “Avalanche deaths continue despite warnings,” The Vancouver Sun conceded in the opening paragraph that the number of people killed each year "is pretty much consistent," despite the increasing numbers of people going into the backcountry. The story also cites a 2005 University of Calgary study of 456 people that had spent time in avalanche terrain, and found that, "most people… were simply out to create a memorable experience and have a good day." Weird. And of the 35 surveyed that had been involved in an avalanche, none had given up playing in the backcountry. Also not surprising.
Another story showed it's typically young men who get caught in slides, and another that snowmobilers die more often than skiers. The last story has a graph that plots snowmobile deaths against ski deaths from 1991 to 2011, and a nice sidebar with tips from CAC Director of Operations John Kelly.
In the wake of these reports, I touched base with Klassen and Kelly. I was curious to know more about the layers within the snowpack. Klassen pointed me toward James Floyer's "Interior Range Status Report,” published Jan. 7. Kelly warned me against the dangers of long-term forecasting. Conditions are constantly changing and backcountry users should rely on their daily forecast, not any presumed outlook. But the paper recognizes that due to a weak, shallow snowpack and persistent weak layers, there is cause for longterm concern. Historically, similar conditions have led to dangerous and unpredictable conditions. The paper also provides a brief chronological sequence of layers and varying scenarios for future loading.
Kelly also explained the technical and comprehensive Avalanche Hazard Assessments they provide with each region's forecast. (They can be accessed by going to the CAC home page, clicking on "Latest Bulletins," then desired region and "View hazard analysis” on the right.)
While I was at it, I touched base with a few other forecasters around North America.
Bruce Tremper, director of the Utah Avalanche Center, offered this (on Jan. 21):
"We lucked out recently because we had a nasty surface hoar layer and most of it was destroyed by rain falling up to 10,000′ and then froze hard as a rock. So it 'raised the ground level' as we call it, by putting a stout ice crust on the snow surface. This has made for a very stable snowpack, at least for elevations below the rain-snow line.”
“But it looks like we are heading into a high pressure ridge, so the foot of nice powder on top of the rain crust will likely become faceted and it will set us up for a very unstable period in the future—potato chips on a pane of glass—as soon as you put a slab on top of it, it’s going to rock and roll."
Brandon Schwartz, a forecaster for the Sierra Avalanche Center
"Recent rain and melt freeze conditions have eliminated any ongoing concerns with specific layers. At this time, the snowpack is now well-consolidated, well-bonded, and in excellent condition to handle new snow loading. Any layers of concern are unlikely to be created until the next storm cycle occurs sometime in February."
Garth Ferber, a forecaster for Northwest Avalanche Center, said:
"Right now the NW snowpack should be pretty stable and content. We have had a couple cycles of rain and/or warm temperatures lately that have caused consolidation and stabilizing. Most reports indicate stable crusts in the upper snow pack."
Colorado Avalanche Information Center director Ethan Greene warned of danger, inconsistency and unpredictability that a layer of surface hoar is causing in portions of the northern, central, and southern mountains. The layer can give skiers a false sense of reinforcement, says Greene. Its inconsistency means that one slope may be fine, while a neighboring area with similar characteristics may result in a massive slide.
"It's kind of the worst scenario in the snowpack," said Greene. "Where you recognize it's there, but you don’t really have signs telling that it's that much of a problem and then you find that special spot and it becomes more of an issue. It's a scenario that we talk about in avi work quite a bit and talk about to the public more, where you have a lower probability of triggering slides, but if you do, the consequences are severe. It's a low probability, high consequence event."
Greene also talked about how "Moderate" and "Considerable" categories cause the most fatalities. "It takes a bit more detective work to figure out what the problem is…" said Greene. He suggested sticking to backcountry protocol and never letting your guard down, regardless of what the previous run told you.