How to Stay Alive in Deep Powder Snow:
Avoiding Tree Well Accidents

Robert Cadman, PhD

For skiers and snowboarders who seek out deep powder, the same snow that thrills can also kill. Experts who chart skiing injuries have documented a significant risk: suffocation after falling, often headfirst, into deep snow depressions around trees (tree wells) or even on open ground. Similar to avalanche-related deaths, most incidents have occurred at ski resorts in the western United States and Canada, though the same risk would be present wherever deep powder conditions are found.

Hazardous tree wells are generally found in areas that get little skier traffic.  Low-hanging branches of coniferous trees may create a sheltered area around the base of the tree where a well of loose snow with air pockets can form. Usually there is no easy way to identify a dangerous tree well by sight, but the risks are greatest during and after major snowstorms.

Tree wells tend to form on the downhill sides of trees, because snow on the uphill side tends to creep downward and become compacted against the tree. Tree wells are also more common in areas sheltered from the wind, because strong winds break up snow crystals and increase snow density.

Stay on Safe Ground

Prevention is all-important because the odds of surviving deep snow immersion are low. Skis and snowboards can end up flush with or below the snow surface, making it difficult for searchers to locate victims. In an experiment in which 10 volunteers were temporarily placed in a simulated tree well, none could rescue themselves.

The most important prevention step is resisting the urge to ski through the trees during extreme powder conditions, no matter how inviting the untracked powder looks. But if the powder is too appealing and you find yourself skiing on timbered slopes:

• Buddy up with another skier or snowboarder and stay within sight of your partner. That means stopping and watching your partner descend, then proceeding downhill while he or she watches you.
• Carry the same personal rescue gear as back-country skiers: an avalanche beacon, a shovel, probe and whistle.
• Remove your pole straps. Trapped skiers have difficulty removing the pole straps, which can hamper efforts to escape or clear an air space to breathe.

 

What If You Go Down?

If you are sliding toward a tree well or a deep snow bank, do everything you can to avoid going down: grab branches, hug the tree or anything to stay above the surface. If you go down, resist the urge to struggle violently. The more you struggle, the more snow will fall into the well and compact around you. Also, your skis or snowboard may knock snow off the branches. Instead of panicking, try first to make a breathing space around your face. Then move your body carefully in a rocking manner to hollow out the snow and give you space and air.

Hopefully, your partner will have seen what happened and will come to your rescue within minutes. If not, experts advise staying calm while waiting for assistance. Survival chances are excellent if you maintain your air space. Over time, heat generated by your body, combined with your rocking motions, will compact the snow, and you may be able to work your way out.

The Physician and Sports Medicine Vol. 27, no 13, 1999