Tiny Avalanches Can Kill You

Post by WildSnow.com blogger | September 5, 2013      
Large avalanches that result in huge debris piles fascinate us. But small slides can be just as deadly.

Large avalanches that result in huge debris piles fascinate us. But small slides can be just as deadly.

Large avalanches look scary. They should be. Monster slides cause certain injury or death if you’re caught.

Nonetheless, an alarming number of tragedies result from small avalanches on somewhat innocent looking slopes. This is especially true in mid-continental snowpacks such as Colorado where small hair-trigger slabs can liquify in an instant, knock you down, and bury you deep enough to require a lengthy dig-out extrication while you suffocate. But the warning about diminutive avalanche slopes applies to any snow climate — especially if terrain traps such as cliffs or gullies lurk below. Here is one experience of my own with the “little ones.”

We are lounging in Betty Bear hut (Colorado’s 10th Mountain Hut System). We look south at an inviting ski slope, a little thing of perhaps 300 vertical feet, steep enough to avalanche but not an obvious slide path; no obvious demarcation such as the classic swaths you see cut into mountainsides worldwide.

There are a few signs, however. First is the shape and exposure of the slope, a northerly facing convex bulge, devoid of trees, wind-loaded with a pregnant belly of snow. The conifers at the base of the slope are not obvious avalanche trees with heavily stripped branches and scarred bark, but to the trained eye they tell a story of vegetation abuse. What I see is enough — with years of experience (including plentiful mistakes) my avalanche eyes are tuned, and the slope looks like something to avoid.

Nonetheless, I need to reach the top of the pitch to take photos of the hut. So we climb a conservative line to the left, on lower angled ground with denser trees that indicate a lower frequency of avalanche activity. About half way up we realize the snow is in bad shape for skiing, breakable crust and worse, so my companion Andrew Meeker leaves his boards stashed below the last pitch of windpack and boots the remainder of the climb.

The slope and our route. Terrain features and a few missing tree branches indicate danger, but the slope is so small...

The slope and our route. Terrain features and a few missing tree branches indicate danger, but the slope is so small...

Just after we top out, the proverbial WHUMP echos through the forest as the snowpack does a massive collapse, birthing a thick hard-slab avalanche just 20 feet below us. We watch in stunned silence as the slab liquefies, then piles up in a deep plug at the bottom of the slope — a killer for sure.

How was our route finding? Our up-track was still intact except for one small section. Where Andrew had dropped his planks, the slide had washed over our line by just a few feet and carried his skis away (Andrew was not a happy camper…).

Our score? If the slide had triggered while Andrew was messing with his skis, he might have been swept away — but then again, if he’d had the presence of mind to take two steps to the left when the slide triggered, he would have been totally safe. I couldn’t help but note that my own tracks were 100% safe. Experience or luck? I’m not sure. I’d give us a “C” for route finding and a “B” for judgment.

Most importantly, note that it was the difference of mere feet that made for one totally safe route, and another that risked death. This validates what I call “micro route finding,” an avalanche safety skill I believe is significantly more important than snow science, and much harder to learn. It is the art of using subtle terrain variations to avoid small, but nonetheless deadly slides.

You cannot gain this skill from books or classes. You learn it by being outside observing the world around you through a lens of fear and conservatism, perhaps while following a mentor who has the knack. And all the while, you’ve got to remember how easily human error enters in — that’s the lesson I learned from this skirmish in the avy jihad.

(The Forest Service avalanche advisory for the day of our adventure was “low/moderate,” but a sudden warming trend pegged the danger way past that. One of Andrew’s skis was lost till he retrieved it that summer. We didn’t need a trip to the underwear store, but Andrew’s eyes stayed wide for a few days, and I returned home humbled, resolving to do better. If anything, this is a good example of how Colorado can build good mountaineers — it’s not a forgiving environment — mistakes are costly — if you survive you learn…)

A few tips for micro route-finding and behavior on a tender snowpack

– Look for a route that chains lower angled terrain with islands of safety so you never set foot on steeper terrain.

– Load a slope with as few people as possible. Keep your party spread out, and travel in small groups.

– Use vegetation to read the slope, but don’t depend on sparse trees to anchor the snow. If conditions are touchy, only trees tight enough to make you cuss will hold snow from avalanching.

– Avoid wind loaded “pillows” and convex starting zones.

– If your route exposes you to danger, pick a line that minimizes the consequences of an avalanche (e.g., getting swept into a gully is worse than tumbling into a fanned out debris pile).

– Consider subtle variations of slope aspect. In Colorado, just a slight tilt to the west or east, rather than dead northerly, can make a route much safer. South facing slopes can be sun hammered enough to be 100 percent safe. Prevailing winds may strip areas down to the ground, making for 100% safe ascent routes.

– Learn the subtleties of wind loading (in other words, throw away the books, forget expensive and time consuming advanced certifications, just go to the backcountry and look/listen/feel.)

– If traveling in a valley during a time of high avalanche danger, remember that large slides can pound the valley floor. These events are usually unsurvivable. Use your imagination as you pick a route, and choose a line that avoids your horror fantasy.

– It bears repeating: Use ridges to reach summits. If the signs of avalanche danger are in the red zone, ski back down your ridge route (use all that skill and expensive gear you’ve acquired to make tight and precise turns on a narrow ridgeline track).

– While skiing down, avoid falling and wallowing on avalanche slopes. If you can’t ski without falling, improve your gear or technique, or dial back your expectations.

– On the way up, avoid post-holing and trenching. If such an option is necessary, spread your group out and linger in safe zones while the leader works. If possible always use over-snow equipment such as skis, a split snowboard, or large snowshoes that don’t punch a deep track. While snowshoes may work well on a track previously broken by a skier, most smaller ‘shoes will cause you to wallow in virgin winter snow. If you’re serious about winter backcountry snowboarding in Colorado, get a splitboard rather than using snowshoes.

– As I mentioned in the article above, travel with a mentor, stay behind him/ her, and think about the moves and choices he/she makes.

– Above all, if you choose to backcountry travel during times of ultra-tender snowpack, be cautious and conservative to the point of absurdity.

We have more about small avalanches:

A few illustrations of dangerous slides that looked innocent.

How does a newcomer to backcountry avalanche safety ID how far an avalanche slope can slide?

A tragic smaller slide takes a person’s life.

Commenters, your ideas?


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26 Responses to “Tiny Avalanches Can Kill You”

  1. Forrest Gladding September 5th, 2013 8:23 am

    A tragic small avalanche took the lives of two children last winter.


  2. Lynne Wolfe September 5th, 2013 9:10 am

    Excellent assessment, Lou. We have been teaching in level 2s the twin tools of detectability and manageability, and I have seen a lot of experienced skiers lately overestimate the “manageability” of small avalanches. I really like what you say about the micro routefinding as well. That stuff you can’t learn from a book, but you gotta get out there and pay attention while doing so. I see too many people plugged into their music or conversation while on the trail; it is hard to pay attention to the subtleties and omit the crucial give and take with a partner if your mind is elsewhere. You are always on the clock in avalanche terrain.

    Just one small correction for you: the “whumph” you heard and felt is a COLLAPSE, not a settlement, which is a strengthening process that happens over time.

  3. Jeff September 5th, 2013 9:20 am

    As someone who is just learning about avalanche safety and hoping to get in the backcountry next winter, thanks so much for the detailed write up. It’s so great to hear the perspective of a veteran and learn what they look for, even though I’m still learning the basics.

    Also, the more I learn about avalanches, the more Colorado scares me, thanks for posting about a successful trip into avalanche terrain!

  4. Ron Rash September 5th, 2013 9:32 am

    Lou, Great timing on your article this morning. Excellent time to sign up for this coming winter’s avalanche courses. Good point, our avalanche classes stress routefinding and good decision making process in avalanche terrain.

    January, 2011 a small avalanche that proved fatal just outside the Snowmass Ski area boundary was one of the smallest killer avalanches I’ve ever heard of. I believe it was less than 14 feet across and went down in to a terrain trap around 20 feet. Much smaller than the Betty Bear avalanche.

    Nice comment from Lynn. You’re not on the Grand?

  5. Lynne Wolfe September 5th, 2013 9:40 am

    Hi Ron- Nope, done with guiding for the summer and working on the October issue of The Avalanche Review. So Lou’s story is timely for sure.

  6. Lou Dawson September 5th, 2013 10:00 am

    Lynne, thanks for the correction, I’ll edit. I need to start using the word “COLLAPSE” as I constantly make the mistake of calling it all “settlement.”

  7. Lou Dawson September 5th, 2013 10:11 am

    Jeff, it’s important to be well “scared” in Colorado. But really, an attitude of caution is the way to go in any snow climate, as for many people it’s human nature to push up against the limits of acceptable risk. In other words, in a “safer” snowpack you might find yourself doing bigger lines in riskier situations, thus taking the same risk exposure as if you were being more conservative on a more dangerous snowpack. It’s really important to think all this stuff through and make conscious decisions and goals for risk management. I see a lot of accidents and meet a lot of people where this stuff appears to never have been addressed. Basically, “human factors” to put it politely, but in a more blunt terminology: “blundering.”

  8. Steve September 5th, 2013 12:51 pm

    Great stuff Lou.

    Not to arm chair here but why not just contour around to lookers left from where the photo was taken and then a gradual approach to the top of that mound via the “thicker” trees? Photo could be deceiving me and don’t know what’s to the left but could that have been an option?

  9. Lou Dawson September 5th, 2013 12:56 pm

    Steve, my recollection is that it seemed more dangerous over in there, more vert or something like that, and the traverse involved a lot more of such terrain than using the tighter line. Definitely something to think about and don’t worry about arm chairing, that’s the whole idea of these types of blog posts, to get us all using our noggins.

  10. Karilyn Kempton September 5th, 2013 1:41 pm

    Lou, thanks for a great piece very worthy of sharing. Helpful tips on micro route-finding and decision making.

  11. Joe Risi September 5th, 2013 1:52 pm

    A micro avalanche this past winter in nearby Burnt Mountain(Snowmass side/slack country) took the life of one skier.


    14 ft wide and only ran 30 ft runoff.

  12. Charlie September 5th, 2013 2:49 pm

    Thanks, Lou!

  13. Mat. F. September 5th, 2013 3:35 pm

    Thanks for sharing!, I personally work in avalanche forecasting and we are always touring around for tests and whatnot. Not long ago we experienced a pretty scary situation as well, before we start a traverse we checked the incline of the slope, 18deg. So we decided to keep going, as someone above said, that ‘whumph’ is a collapse, well we got that, even with 7 to 10m of spreading with eachother, the fracture was so big we had to keep going far away to measure the entire fracture. It was a ‘controled’ risk that we took, we knew it was unstable but it wasn’t gonna slide down, as you said. Learning on field is essencial.


  14. damian September 5th, 2013 3:53 pm

    Good article!

    A person died in a very small avalanche early last season in Hokkaido, Japan. I know of other close calls from small debris fields and “only sluff”.

    Formal training builds a good foundation, but many meaningful days of experience need to be gained at every opportunity. It is so important, yet understandably lacking due to geography and work+family demands. Signs of instability are subtle and not always present, so you need to get out there often to know what hollow sounding snow, for example, really feels like (and looks like). Or where and when to find shooting cracks. Learning to use terrain to solve problems takes even more time breaking trail outside of lifted ski areas.

    Get out there.

  15. Mike September 5th, 2013 6:46 pm

    Good overview and a reminder for the (hopefully super-rad) season to come. Just one criticism I’ve seen a few times: “I couldn’t help but note that my own tracks were 100% safe.”

    This fallacy has a name: survivorship bias. Just because your tracks are intact doesn’t mean that they were in a 100% safe location, even under those same circumstances (not to say that your tracks necessarily *weren’t* in a 100% safe location).

    I look forward to much more banging of the avalanche drum. We’ve lost too many good people recently.

  16. Wilf September 6th, 2013 11:26 am

    “We’ve lost too many good people recently.”
    For sure.

  17. Lou Dawson September 6th, 2013 1:59 pm

    Mike, thanks, you are correct and that’s a good thing to point out about my take, which is indeed biased by default. Andrew and others probably had a different idea, like perhaps we should not have even been up there in the first place! The whole incident might have been a total flub on my part. Losing a ski definitely indicated a close call. Lou

  18. dale persing September 7th, 2013 5:49 am

    Here in the NE our season is a ways off, but spatial variability and micromanagement are our bread and butter. Nice concise review of avy priorities and REALLY nice terrain pic – should be used in classwork or a snow science text.

    Thanks for the primer.

  19. XXX_er September 7th, 2013 9:07 am

    A local was killed in an aviy while working last october which seems damned early, a small sluff swept him over a cliff

  20. Matt Kinney September 7th, 2013 11:49 am

    This car-sized avalanche nearly drowned me about 5 years ago.

    We had just finished a huge run off Goodwills and was traversing high above a 10′ deep water hole when it broke. Suddenly, I was floating in water on top of a quickly melting slab. To make a short story short. My partner Sam Owen, was unable to help, but snapped this picture of my exhaustion after struggling to get off the floating slab. I recall removing a ski and anchoring myself to the “shore” and crawling to safety. As you can see the slab has melted. From start to finish, it was about 5 minutes of controlled panic with one boot full of water. Another minute and things would have got super messy.

    This was about 300 yards from the trailhead, further proof
    avalanches do not care how far you are from your car.


  21. Harpo September 7th, 2013 12:10 pm

    Great article Lou! Very true that micro avis r an issue in all snow climates. I remember a senior patroller at timberline on hood was killed in a micro avi in a gully either in bounds or just out of bounds. I think it was near the summer up trail on the climbers right side of the resort. I don’t remember the other details.

    In a few of the avi classes I have taken I have asked “what is the difference between a sluff and an avalanche?” I think the answer was that a sluff is inconsequential /unless/ u also have terrain traps such as a cliff or a gully. Big mountain skiers (mostly in AK) talk about “sluff management”. Does the concept of sluff management have any relavence to us mere mortals? Unfortunately I have taken the avi courses at Lake Tahoe community college too many times and I cannot repeat them so I won’t be able to ask that question in class.

  22. Jason September 9th, 2013 8:05 am

    It only takes that little bit of snow in your wind pipe to call the grim reaper. I’ve been in countless small slides at the resort and thank God only a few in the backcountry. Education has taught me a ton though and it has helped me mitigate as i gain more experience and get older. I still realize that snowpack can be unpredictable. It’s nice to see simple to use transceivers and avi packs making such an inroad… For me, if the snowpack is questionable, I take it “absurdly” mellow 🙂

  23. Jon September 9th, 2013 5:53 pm

    Well I have been backcountry skiing for some 35 years, when we started there was no avy knowledge per se. All we needed to know was not to get caught. The recent advent of gear; Skis, boots and the rest including avy safety gear has to my not done much more then lure people into the backcountry with with a minimal set of skills including using your head. I am an engineer by trade and try to explain to people that a 10x10x1 foot slab of snow (anywhere from powder to wind slab) can weigh bin excess of 500 lbs [that is 100 cubic feet of snow, water weighs 60 lbs/ft3 (that is 3 tons of water btw) if the water content of snow is say 15% that is still about 900 lbs { From the NRCS Website::::Most snow that falls in the Cascade Mountains of Washington and Oregon tends to be higher density snow. In the Cascades, snowpack densities are around 20-30% in the winter to 30-50% in the spring. However, east of the Cascades, the snowpack density is much less. Typical values are 10-20% in the winter and 20-40% in the spring.] I am in the Sierras.

    That is more than enough weight to debilitate you or push you in a direction you may not want to go. Too many people are looking to the big avalanche and not thinking about merely being incapacitated and a burden on those you are with….

  24. hortence September 24th, 2013 12:46 pm

    “Nonetheless, I need to reach the top of the pitch to take photos of the hut. ”

    This sentence jumped out at me. Maybe it should be filed under “Human Factor Risk.” After all th ere is a big gap between “need” and “want.”

  25. Lou Dawson September 24th, 2013 1:18 pm

    Hortence, good point. In this case the backstory is that it was a “need” in that I was getting photos for the hut company and for guidebooks, but it wasn’t enough of a “need” to get killed over!

  26. Jeff October 25th, 2013 9:45 am

    Jason, I don’t know you nor your experience (for all I know you’re an avy professional), but reading your second sentence made the hair on the back of my neck stand up! Hard for me to reconcile taking it ‘absurdly mellow’ and being involved in ‘countless small slides in-bounds, and several out-‘. Be safe out there.

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