It’s been a huge week for the mountains of California, with some ski resorts seeing several feet of snow in just a few days. At Mammoth Mountain the past three days alone brought over 4 feet of snowfall, forcing closures of lifts, lodges, and the entire mountain at times. Avalanche danger is the obvious risk with this heavy snow, but Mammoth is making a point to highlight the risk of snow immersion suffocation (SIS) that comes with the weather.
“Deep snow remains a serious factor. The risk of Snow Immersion Suffocation (SIS) is real, so avoid tree wells and deep snow near trees. Always ski or ride with a partner, keep your group in sight, and stay alert for obstacles beneath new snowfall.” – Mammoth Mountain
Snow Immersion Suffocation safety should stay at top of mind when skiing or riding. SIS accidents occur when a skier or snowboarder falls into a tree well or area of deep loose snow, becoming immobilized and trapped under the snow leading to suffocation. Falling headfirst is the most common position where SIS incidents occur.
A tree well forms around the base of a tree, containing a mixture of low hanging branches, loose snow, and air. Evergreen trees specifically can form deep tree wells when low hanging branches block snow from filling in and consolidating around the base of a tree, creating a hidden void. There’s no way to easily identify if a tree has a dangerous tree well just by sight, so all tree wells should be treated as dangerous.
Breathing becomes difficult when one is trapped under snow, leading to suffocation without an immediate rescue. 90% of those involved in Tree Well/Snow Immersion Suffocation hazard research experiments could not rescue themselves, making it incredibly important to ski or ride with a partner in ungroomed terrain.
Snow Immersion Suffocation Safety
To Avoid Snow Immersion Suffocation:
- Ski or ride with a partner.
- Avoid tree bases when skiing or riding in deep snow.
- Attempt to fall feet first if you are going to fall.
- The risk increases with more snow.
If You Go Down:
- Yell or use a whistle to get attention from your partner.
- Do what you can to keep your head above the snow, rolling around, grabbing tree branches or the tree trunk.
- Keep your feet below the level of your head if possible.
- If you become immersed, make a space around your face and protect your airway, staying calm and trusting that your partner is on their way.
- If you can, use your cellphone to contact the mountain’s emergency hotline (760.934.0611 for Mammoth)
If Your Partner Goes Down:
- Do not leave to get help.
- Stay with your partner, call for additional resources, and use a whistle or yell for assistance.
- Call for help (760.934.0611 for Mammoth) if you can.
- Evaluate scene safety for yourself.
Snow Immersion Rescue Efforts
- Go straight for the airway and make sure to keep it clear.
- Do not knock more snow into the hole.
- Determine where the head is and tunnel in from the side. Don’t try to pull the victim out directly from where they fell in.
- Continue expanding the tunnel to the airway until the body can be removed.
