Two snow safety experts from Washington State ski areas want to alert skiers and snowboarders to hidden dangers in trees after deep powder snowstorms. That danger comes from tree wells filled with soft snow that can trap skiers. While statistics so far this year may show that their message is being heard, the number of fatalities inside ski resorts has grown in the past 20 years to levels nearly on par with out-of-bounds skier avalanche deaths.

Paul Baugher, director of Crystal Mountain Ski Patrol and Northwest Avalanche Institute, and Gwyn Howat, operations manager at Mt. Baker Ski Area, have been the steam behind the research on Snow Immersion Suffocation (SIS). Their findings have been updated on the Deepsnowsafety.org website this winter to raise awareness and increase education for skiers and snowboarders.

So far this winter, the SIS news has been good. “There has been one confirmed SIS fatality in British Columbia and no fatalities yet in the U.S. this season,” says Baugher. “This is remarkable news as December and January are the most likely months for a SIS to occur. Statistically, this trend is not likely to last.”

Fresh snow after a storm cycle produces conditions ripe for SIS — conditions that are heightened across the West due to coniferous trees that act like Velcro trapping snow. Deep unconsolidated snow around creek beds and soft loose snow in tree wells can trap a skier or snowboarder who falls in head first. Self-extraction is rare; suffocation is more common.

Two winters ago, SIS spiked in U.S. ski resorts to nine fatalities, the highest level in 20 years. That year, two SIS fatalities occurred within 10 days at Whitefish Mountain Resort. In the U.S., most years see an average of four SIS deaths. From 2001-2011, the ski resorts in three states of California, Colorado, and Washington tally up the highest number of SIS fatalities.

With the low numbers of SIS fatalities so far this season, Baugher points to increased awareness and education. “It is important to note that there have been a large number of close calls reported this season at western ski areas — particularly in the Northwest just before the Christmas holidays,” he says. “While we are certainly not out of the woods yet, I have no doubt that 10 years ago at least several of these close calls would have been fatalities.”

Baugher and Howat revamped their website on deep snow safety for this winter. It includes new data, diagrams, photos, and videos to help skiers and snowboarder educate themselves about the risks of SIS. The research also points to specific things that skiers and snowboarders can do to increase safety. Top on the list is skiing or riding with partners.

You can learn more about SIS by educating yourself. Find the website here.