On a powder day, there are no friends. That saying is probably as old as the first ski lift, but it's a dangerous wisdom - as was demonstrated at Montana's Whitefish Mountain Resort earlier this winter.
Two snow riders - one a 16-year-old on skis, the other a 28-year-old on a snowboard - both plunged head-first into wells surrounding trees at the resort. Hung upside down by their boards, wedged by the tree and branches, and choked by the collapsing snow, they could barely move - or so the evidence suggested when they were found. One was dead, and the other hung on for several days, although never regaining consciousness.
"It doesn't happen every place every year, and it doesn't necessarily happen every year," says Michael Berry, president of the National Ski Areas Association, a trade group.
Prodded by his group, ski areas have become more aware of the potential peril in recent years and have taken increasing steps to remind customers of dangers.
An average 38 people die annually at U.S. ski areas from collisions, avalanches and the trauma from hitting trees. Of this total, an average 3.3 per winter since 1990 have died in tree wells or in other deep-snow immersions not resulting from avalanches.
Like avalanches, the danger of immersions spikes during and immediately after major storms. For snow riders, it's hard to imagine too much powder. But in the 1990s that's precisely what happened in Vail Mountain's Back Bowls when a man died after plunging into what might be described as a snow hole and was unable to right himself. The Eagle County coroner's report was unavailable, although a press report at the time said the man drowned in the snow.
If cold persists, the loose snow around trees can remain unconsolidated for days, even weeks.
Again like avalanches, avoidance is the best precaution. If caught, having somebody nearby is virtually your only hope. Plans to reconnect at the ski lift don't quality. People have died after being inverted in tree wells within 20 minutes, perhaps less.
The danger of deep-snow and tree-well immersions was not broadly appreciated until relatively recently. But many snow professionals have had their own brushes.
Dale Atkins, president of the American Avalanche Association, defied the statistics. Skiing alone at Loveland Ski Area, he got upended in a tree well. Unlike most of those skiing alone, he was able to release his bindings unaided.
"That gave me enough space that I was able to clamber out and then shake the snow out of my ears and jacket and head down the hill," he says.
The expert in deep-snow immersions is Paul Baugher. A 30-year veteran of the ski industry, Baugher gave little thought to the first tree-well fatality at Washington's Crystal Mountain, where he is director of ski patrol.
"We thought it was a real fluke," he says.
A decade later, another one occurred. "It really made me start looking into this," he says.
Conducting an experiment in 2007, Baugher found just how difficult it was for somebody fully inverted in a tree well to escape without assistance. "It was freaky to watch," he says.
With the vigor of an investigative reporter, Baugher collected reports from ski areas. He found the average age of snowboarding victims was 23 and of skiers 32. Most were on moderate slopes of dispersed trees relatively close to groomed trails. Most were males.
Baugher finds no evidence that snowboarders are more susceptible to death by snow immersion. "Releasable bindings are not the answer. Having a partner is," he says.
Has the growing popularity of off-piste tree skiing resulted in more deaths?
Some think so. "Even within the ropes, we are seeing people skiing areas that were only lightly skied 20 to 25 years ago. Now, they're skied or boarded heavily," says the NSAA's Berry.
He points to the evolution of snow-gliding gear as the cause. "With the narrow-waisted 215-centimeter skis, it was the rare person who could enjoy it and have fun."
In fact, an average 3.2 deaths during the 1990s has grown to 3.8 deaths during the last decade. Baugher believes his educational efforts - he has a website called www.treewelldeepsnowsafety.com/ and has spoken at many ski industry conferences - have prevented a higher death toll.
Colorado's Steamboat Ski and Resort has become aggressive in alerting customers to dangers after three tree-well deaths in recent years.
"A lot of people say there are no friends on a powder day, but we educate our guests about the benefits of having friends on a powder day," says Steamboat spokeswoman Loryn Kasten.
Large coniferous trees with broad canopies in areas of deep snow, such as is found in maritime climates, are more likely to have dangerous wells.
Colorado tends to have less danger with its forests of lodgepole pines, their canopies more narrow. Still, Colorado ranks third for fatalities, behind British Columbia and California, because of its huge number of snow riders.
The easy part, says Baugher, is that the same rules can be taken from the avalanche safety playbook. Stay in sight of your buddies, he says, as they're your only hope.
Allen Best publishes a newsletter called Mountain Town News. He can be found at www.allenbest.net.