AFTON, Wyo. — After a snowmobiler was caught and killed in an avalanche in the backcountry south of Afton on Sunday, the Bridger-Teton Avalanche Center (BTAC) has released preliminary information about the snowpack at the site of the tragedy.
A video posted to Youtube by BTAC on Tuesday morning outlined the terrain, slope angle and crust layer on which the avalanche failed. Two BTAC U.S. Forest Service forecast staffmembers traveled to LaBarge Creek in the Salt River/Wyoming Range forecast zone, just east of Commissary Ridge, and dug a snow pit to examine the snowpack layers.
“This is a tragedy, and we came out here in hopes of learning something that can help us with our safety messaging and forecasting going forward,” said BTAC’s Travis Baldwin in the video.
According to Baldwin, the avalanche took place at about 8,900 feet in elevation on a west-facing aspect with a 38-degree slope angle. Avalanche.org states that most avalanches occur on slopes with an angle between 30 and 45 degrees.
The proximity to LaBarge Creek was its own source of danger, as a terrain trap and a common location for surface hoar to exist. Baldwin said that a well-developed layer of surface hoar was present directly on top of the crust that formed around Christmas. This layer was buried less than 2 feet deep, creating a persistent slab problem in the area that failed on Sunday.
Baldwin stated that since there haven’t been a lot of observations or evidence surrounding this persistent slab layer, it’s important to fall back on typical avalanche safety travel guidelines: “steering clear of steep convexities and rollovers, creek beds that act as terrain traps, [and] thin spots in the snowpack, which can be hard to identify.”
The fatality on Sunday was the second avalanche-related death of the winter in the region.
