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Whether you’re a new or experienced skier, you should know the dangers of tree wells and how to avoid them…
What is a tree well?
A tree well is the hidden area of a tree that’s covered by deep snow. Over the winter as snow builds up around a tree, the branches stop the snow from condensing which creates a large air pocket of loose unstable snow.
Hidden beneath the branches of snow covered trees are deep pockets of air that goes to the base of the trunk. This tunnel of space is in the shape of a well and it is completely obscured by the snow that has collected above.
For an unwitting skier, who goes near a tree well -- their weight will easily suck them into it and lodge them dangerously into the snow, potentially suffocating them to death.
Tree wells occur everywhere there is plenty of deep powder, so any skier who goes off-piste or backcountry skiing where there are trees in the landscape will need to be wary of them (read my guide on skiing through trees).
A tree well can happen under any tree, but they are typically the most concealed and the most deadly when snow builds up under trees with lots of branches.
Hardwoods and trees with smaller or less branch density, don’t create very deep tree wells and so don’t pose as significant of a threat.
Conifer trees that are most common in ski areas -- trees like fir, pine spruce and larch typically have dense need-like leaves. These dense branches hold more snow and prevent new snow from reaching the ground beneath. Which means larger, more concealed wells.
On these types of dense trees, snow collects across branches and creates an umbrella effect, preventing any dense snow from forming around the tree. As the snow builds all around, layers of snow covered branches disappear under the rising landscape.
From the outside there is nothing to see but a tree emerging from the ground. In wait lies a dangerous trap.
The taller a tree and the more branches it has, the more likely it is that a bigger tree well will form. Snow drifts, the slope, and tree angle will all affect how the snow forms around a particular tree.
In deep snow, up to a third or more of the tree can be hidden below the snow. All that hidden space is a potential trap and the bigger the tree, the bigger the radius around the tree which is susceptible to collapse.
Tree wells can range from an arm’s length to double the height of an adult skier.
Tree wells are dangerous because they are essentially hidden pockets of air that can cause injury from falling, and result in a skier being quickly surrounded by snow that blocks their airways.
What is tree well & snow immersion suffocation (SIS)?
Snow Immersion Suffocation (SIS) is the main danger that tree wells present and it occurs when a skier is trapped in snow and can no longer breath.
During the 2015-16 season, there were four fatalities resulting from SIS incidents at U.S. ski areas.
When a skier falls into a tree well, they usually fall in head first and become trapped in an upside down position -- with their head buried into the side of the well.
As they move, more snow falls in around them and can quickly entomb them in the snow.
Quickly wedged in and unable to move many solo skiers who don’t have help can be overcome by the lack of air and suffer death from snow immersion suffocation.
65% of people that die from SIS, are skiers stuck in tree wells. It’s landing head first in an inverted position that creates the danger. (Source)
Why are so tree wells so dangerous?
Tree wells are dangerous because they are hidden from view and they are very difficult to get out of.
It has been reported that 90% of skiers or snowboarders trapped in snow-covered holes can’t free themselves alone.
Because of the angle at which most skiers fall into a well, it makes it extremely difficult to move and wiggle to an upright position.
Skis and poles further hamper a skiers ability to move and even very fit adults will be exhausted by every move as they struggle to free themselves.
With each movement, more snow from above is likely to fall and make escaping that much more difficult.
The larger a tree well the steeper the fall for the skier and hitting the tree head on could result in a serious injury (reason to wear a helmet).
That said small trees can still pose a danger and a small well only a meter deep can pose a serious threat -- if you hit at the wrong angle.
Moreover -- much like an iceberg where much of it is submerged beneath the water -- a larger tree could appear small if most of it is concealed under snow.
A steep gradient can also cause snow to drift and build up to enormous heights. Stay safe and avoid getting too close to trees when skiing.
The risk of skiing near tree wells is the same as skiing in deep powder during an avalanche risk.
Tree well deaths account for 20% of ski area fatalities in the US, Source.
Where are tree well accidents most common?
Tree wells are most common in areas of the mountain where there is fresh powder snow. Valleys, troughs and shaded parts of the mountain tends to have colder snow with more layers.
Tree wells occur all over the mountain and any area that’s backcountry and off-piste that has trees can have snow wells.
You can avoid snow wells by sticking to groomed ski slopes or skiing cautiously around trees.
When are tree well accidents most common?
Tree wells are the most common after and during snowstorms. The more snow that falls in the area, the larger the tree wells will be.
More snowfall means deeper snow and a higher ground level at which you ski. Over the season snow builds in layers and so tree wells are at their peak in mid-season and just before temperatures rise in spring.
How to avoid falling into tree wells?
- Avoid skiing close to trees. If you’re skiing backcountry or off-piste, pick a trail with minimal trees.
- If you’re skiing through a forest or near trees, slow-down!
- If there are trees either side of you, aim for a center line through trees.
- Skiing near trees will always incur a risk -- stay on the slope until your a very good skier able to stop and control your speed at will ⚠️.
- Do whatever you can to stay OUT of the tree well.
If you loose control, look between trees and not at trees. Your body follows where your eyes look.
Paul Baugher, Crystal Mountain Ski Partrol Director
How to escape a tree well?
Grab the tree or branch.
If you find yourself falling down a tree well, reach out and grab anything you can. Holding onto a branch of the tree with all your might will prevent you from falling all the way into the hole or at least slow your momentum.
With any luck, you can stop yourself before you fall down into the well or slow yourself so you don’t become wedged into the tree well wall like a projectile.
Whatever you can do to avoid entering the tree well head first will enormously help you to get out alive. As your falling in, roll over, spread your weight and use your skis and fight to stay upright.
Find an air pocket.
If you’re out of luck and find yourself inside the well, then you’ll need to act quickly to find an air pocket of space to keep breathing. Keep you arm up above your face to keep as much snow as possible away from your face.
Adrenaline will have kicked in and you’ll go into fight or flight. Try to find an air pocket, but be aware that violently moving may send you down further into the well.
Make a decision.
If you’re in an air pocket and got some room to breathe and you know your ski buddy will rescue you in the next minute or two then it might be best to relax and wait it out.
If there’s no help coming, you can’t reach your phone or you can’t breathe then you need to act fast and try to get out with all your might.
Use a rocking motion and try to carve out space in the snow to grow your air pocket.
Turn your body slowly and try and move to an upright position. Try to grab a branch or the trunk of the tree and pull yourself up.
It will take lots of energy and determination, but use all your grit and muscle to drag yourself up and out.
Use slow, deliberate rocking movements with your body. This will create air space around you, and the body heat generated may help the surrounding snow to become a little more compact, making it easier to climb out.
Once you are out, rest and recover before making your way downhill. Call for help if you need a hand getting down -- you don’t want to fall into another well through exhaustion.
How to survive a tree well?
If you’ve tried to get out, but your stuck but alive in an air pocket then read on…
It will be difficult, but try not to panic. The more you panic, the more energy you will use and the more of your limited oxygen you will breathe.
If you were skiing with a buddy or there is a chance there are people nearby shout and scream as loud as you can to get their attention.
Take out your phone and call for help. Call anyone you know on the slopes, the ski patrol, the police anyone who can get help for you.
📞 It is a good idea to have set up active voice control before you go skiing, so if you’re stuck and unable to reach your phone you can attempt to dial using Siri or voice control. Always keep your phone in a chest pocket for easier access. Save the ski patrol or rescue number of your local area in your phone before you set off.
If you have a whistle blow it.
If your ski poles are reachable, use them to push a hole through the snow as a way to get more oxygen and to reach the outside.
Be aware that this will cause more snow to fall on you, so be smart about how you build your way out of your hole.
If help is on the way and you have enough space to breathe, then it’s probably best to wait for rescue then risk a chance of destroying your air gap.
You’ll have to weigh up the decision on whether you wait for the help or put all your energy into moving snow for an escape.
Always ski within visible distance of a friend who can be there to rescue you from the very beginning. 1-minute skiing down can be 1 HOUR hiking up.
Tree well survival tips
- Never ski backcountry alone
- Always keep sight of your ski buddy when off-piste. Regularly check for them and seek them out if you can’t find them. Follow their ski trail if you can’t find them. If your buddy is stuck they will need help ASAP, every second will count. If their airways are blocked by snow, they’ll have only a few minutes of life.
- If you ski in the backcountry, bring a whistle, small snow shovel, fully charged mobile phone with voice control or radio and a transponder or RECCO device.
- Only ski near trees if you are an experienced skier.
- Don’t use your ski straps when near trees and off groomed slopes -- as its easier to maneuver without a pole wrapped around you.
- Avoid getting too close to trees and ski slowly through forested areas. It’s much better not to get into a tree well than trying to get out of one. If you choose to go near trees be aware of the risks and only take good skiers with you. Work your way up to more challenging territory. Don’t try to ski a backcountry forest on your second week of skiing.
How to rescue your friend from a tree well?
YOU are your partners best chance of rescue.
If your buddy is stuck in a well and you’re the rescue -- then you need to act fast. Be wary of getting trapped yourself, be cautious yet decisive.
Use a shovel or your bare hands and dig them out, by digging down to the level of the skier OR pull them out by their legs. The method you choose depends on how deep the well is and the position of the skier. You’ll probably need to use a combination of both shoveling and pulling.
Depending on their position it may make sense to remove any skis or poles that are caught up or blocking them from escaping.
It’s always easier to pull them out from the downhill position rather than fighting against gravity.
You can use the end of a ski or snowboard as a make-shift shovel if you don’t have one to hand.
The priority is getting them breathing, shout at them and tell them to stay calm and that you are going to get them out. Work as fast you can to pull them out without getting stuck yourself.
Once you’ve dug enough snow to access the well from the side it should be much easier to get to them and prevent them from suffocating.
Once you’ve reached them and their head is free, calm them down and give them reassurance.
Once you’re safe and rescued call for extra assistance to get them down the mountain if they have any injuries or are unable to ski down themselves.
How do I know if a tree has a well?
It’s very difficult to tell if a tree has a well beneath it because by their very nature they are concealed.
If you’re skiing in deep powder then its pretty certain that many of the trees around you will have wells beneath them.
If you can see the tree trunk, then the tree is likely to have less of a well, but a small well can still be dangerous.
Always presume a tree in snow has a tree well.
Be wary of all trees and leave a wider gap between you and the tree when skiing in deeper snow.
Stay vigilant and ski close to your buddy. Look over your shoulder often and very aware of any upcoming trees.
there is no easy way to identify if a particular tree has a dangerous tree well by sight therefore, treat all tree wells as dangerous.
Why is it easy to suffocate in snow?
Snow can quickly turn from fluffy to deadly. Pressure, weight and a build-up of snow can change light crystals into a dense & heavy weight.
You can no more breath in snow as you can in water.
Hit the snow at the wrong angle and you can become stuck in the snow. Too much snow will block your airways and stop you from breathing oxygen.
Too little oxygen and the snow will suffocate you as if you were trying to breathe underwater.
If you are ever stuck in a tree well, then try to find an air pocket and be very decisive with your movements.
The more you move, the more the snow around you will collapse and fall into your path.
In a worst-case scenario, you’ve got your head down, you can’t get your skis off, and your hands are stuck, It’s easy to choke on powder snow because it’s so light, dry and fluffy, so you inhale it quickly.
Ian MacMillan, Ski Canada Editor
Ski equipment to combat tree wells.
- Snow shovel
- Knee Pads
- Avalanche Beacon
- RECCO device
- Waterproof Radio
- Leatherman Multitool
- Ski Helmet
- Cell phone with resort emergency number.
Key points to remember
- While skiing backcountry unstrap your poles so they don’t become tangled during a fall.
- Grab tree branches during a fall.
- Do all you can to not land head first into the well.
- Always stay in visible distance of your skiing partner.
Pylon wells & other snow wells!
It’s not just trees that have wells. Any larger object that is resting on the ground, such as pylons can have massive snow builds ups and concealed cavities.
In deep snow always be wary of skiing too close to any objects that extend out of the ground.
Tree well survival stories
Although the survival rate is not great, there are many skiers who have survived a harrowing tree well ordeal.
One man, James Drummond was trapped in a tree well for 55 minutes before being rescued by ski patrol.
Luckily he had a large enough air pocket to breath and after a grueling 14 minutes, he was able to reach his phone and call for help.
His main concern was a rapidly falling body-temperature as he lay wedged into the cold snow.
Luckily the ski patrol was able to locate him before he suffered serious injury and he made a full recovery.
Top tips for skiing in trees
- Know the area, ski with someone who knows the area and keep a lookout for any risk of avalanche or cliff edges. If it’s new territory, look on your maps before skiing or ask locals.
- Look where you want to go. Don’t only focus on what to avoid, but look between the trees at your route.
- When coming near branches put your hands up to protect your face.
- Avoid sharp or fast turns near trees.
- Keep your poles unstrapped so they don’t get caught on a branch or hurt you during a fall. It’s easier to pick up a dropped pole than have it cause serious damage to you.
- Don’t ski too close to trees.
- In deep powder keep your tips up and or use skis with a shape designed for powder. It’s very difficult to ski in piste rockers on deep snow without getting stuck.
- Always ski in groups of 2 or more and never ski more than a few trees distance from each other.
- Always maintain a clear eye line to your ski buddy.
- Carry safety equipment and always wear a ski helmet.
- Skiing in powder means you’ll need ski jacket & trousers with a higher waterproof and breathability rating to keep dry.
Plan ahead, look for your next turn, this is about anticipating the terrain, not just reaction.
As you’ve learned tree wells are no laughing matter. Only ski near trees if your a competent skier that can stop, turn and control skis in deep snow.
If your planning a day of backcountry skiing, always ski with a partner, stay close and carry a collapsible shovel and a phone with voice dial.
If you enjoyed this article, please share it with someone who you think might benefit from this knowledge.
Have fun and enjoy the powder.