Chilling Statistics
Recent avalanche deaths attributed to high use and continental snowpack
By Ed Bushnell
Photos by Wade McKoy
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| Mark Kozak skied safely off the edge of this small, anticipated slab. |
On the surface, the statistics are chilling.
Fifty-two people have died in avalanches in western Wyoming since 1911. Of those 52, 16 fatalities have been in the last three seasons.
What’s the cause of the severe increase? Bad snow? Lack of education? An increase in backcountry use?
Probably a combination of all three, said Director of the American Avalanche Institute Rod Newcomb.
The snowpack hasn’t necessarily been more dangerous over the past few years, just different. According to Newcomb, there are two types of snowpack: maritime, wetter snow usually seen closer to the coast; and continental, drier, usually seen inland. Western Wyoming’s snowpack frequently resembles a maritime snowpack, which tends to stabilize quickly after storms.
During the late 1990s, while backcountry skiing increased dramatically in popularity, the Jackson Hole area had several winters of generally safe, maritime snowpack. However, a continental snowpack blanketed western Wyoming during the winter of 2000-2001. In December alone of that year, three people died in avalanches in the Tetons; all of the avalanches were triggered on a persistent weak layer, a result of the continental snowpack.
The 2002-2003 winter season started out much like the 2000-2001 season, with an early set of snowstorms followed by cold, dry weather, creating an unstable surface typical in a continental snowpack. Over the weekend of November 9, a storm dropped over a foot of new snow in the Tetons, on top of the unstable surface. Two skiers were buried in separate incidents on Sunday, Nov. 11, when they triggered avalanches that slid on the unstable layer; fortunately, both were dug out by friends just as they started to lose consciousness.
A series of storms and warmer weather in early December caused the snowpack to bond, resulting in a safer snowpack. But then another cold, dry system settled over the Tetons and another fragile layer was created. This layer was more persistent, and the results were tragic.
In late December, there were no reports of burials—the snowpack was so unstable, people couldn’t even get to the avalanche zones before the slides were triggered.
“Skiers were triggering avalanches on steep slopes as they approached,” Bob Comey, an avalanche forecaster with the Bridger-Teton National Forest, said.
On January 3, the wind blew hard, creating a crusty layer on the surface of the snow. This made the snowpack slightly more stable, and ironically, much less safe. Now backcountry travelers could get onto the dangerous slopes before the avalanche triggered.
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“An increase in stability resulted in an increase of danger,” Comey said.
On January 4 a snowboarder died in an avalanche on Teton Pass. The same day, a snowmobiler broke his femur after being caught in an avalanche on the west side of the Tetons. And the next day, a teenager was killed in the Salt River Range when a slope that had been safely traversed by two snowmobilers moments before slid.
The rest of January saw no respite from the dangerous conditions. A skier was partially buried outside the boundaries of Grand Targhee ski area on January 7, and a snowmobiler was caught in a slide in the Snake River Range on January 8. On January 25, a snowmobiler was killed when he was caught in an avalanche on Togwotee Pass.
Although conditions were less than ideal on all slopes, they were especially treacherous on north- and east-facing aspects. About this time, some of the largest avalanches ever evidenced in the Tetons thundered down the mountains.
Newcomb saw the debris in Cascade Canyon from an enormous slide off the north side of Teewinot Mountain that he believes was a once-in-200-years-event. What made the slide so gargantuan wasn’t a deep snowpack, but rather a weak persistent layer that extended from high up on the mountain all the way to the canyon bottom. As the slide moved down the mountain at approximately 200 miles per hour, Newcomb said, it kept picking up snow as the weak layer kept failing.
Finally, warmer temperatures stabilized the snow in late January. There were two more fatalities—a local skier was killed in a slide in a permanently closed area of the Jackson Hole Mountain Resort on Feb. 10, and a snowmobiler in the Salt River Range on Feb. 24. However, the two avalanches were comprised of recently fallen snow on new layers, rather than faceted snow on old, weak, persistent layers.
Newcomb said backcountry users need to be aware that western Wyoming’s snowpack can be characteristic of a continental snowpack at times, not just the maritime snowpack that is more often seen. When digging a pit for snowpack analysis, skiers and snowmobilers need to look out for the weak persistent layers common in a continental snowpack.
“Variables in our normal snowpack screw a lot of people up,” Newcomb said.
However, both Newcomb and Comey believe increasing avalanche awareness and education is bringing the relative death rate down. Comey said for every avalanche death, there are several stories of incidents that could have been fatal except for the quick thinking and preparedness of party members. Comey also pointed out that there are many more avalanche-education classes than ever before, and the classes are always full or nearly full.
Better forecasting technique, and improved communication of the forecast, also helps make sound decisions about where or whether to venture into avalanche terrain at any given time. For example, Comey and other Bridger-Teton National Forest employees installed sensors at various locations in the southern Tetons this fall. The sensors will allow forecasters to collect data on avalanches even when they go unreported.
But the biggest reason for the recent jump in avalanche fatalities is the high number of people who travel in avalanche terrain, according to Comey. It’s only natural that as backcountry use rises exponentially, the number of fatal incidents will increase. That doesn’t mean travel in avalanche terrain is becoming more dangerous.
“Statistics don’t show how many people went out and came back,” Comey said.
Ed Bushnell is a writer and skier who lives in Jackson Hole. As of Sept., 2003, he has skied 35 consecutive months in the Tetons.
The Jackson Hole Skier is a free visitors’ guide published annually and distributed at hundreds of locations throughout Jackson Hole, Cody, and other regional communities. To receive a copy in the mail, send $5 to Jackson Hole SKier, P.O. Box 1930, Jackson, Wyoming 83001.
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