Geartrade: The Definition of Avalanche Terrain
At Geartrade, it goes without saying that we love talking about skiing. And we love talking about ski touring in the backcountry. But you can’t talk about ski touring without talking avalanche safety. And one thing that’s top-of-mind this week (as it’s dumping multiple feet of snow here in a fabulous February storm) is avoiding avalanche terrain while danger is high.
The definition of avalanche terrain merits a quick discussion, as our seasoned backcountry skier crew is often asked by beginners wondering how to stay safe. The simplest way, when danger is elevated, is to avoid avalanche terrain altogether—you can still ski glorious snow while the steeps settle, shed, and stabilize.
What IS avalanche terrain, and how do I avoid it when backcountry skiing?
We’re so glad you asked. If you understand what avalanche terrain is, you can figure out how to avoid it, staying safe whenever danger is high or you have any other risk element at play, such as touring alone or with a beginner. (Note, there are big risks in touring alone, touring with beginners, or touring for that matter—but this article will help explain the avalanche avoidance part.)
Avalanche terrain is, by definition, any slope steeper than 30 degrees—and anything beneath (or in the path of) slopes steeper than 30 degrees. Nearly all avalanches happen on slopes between 30-45 degrees in steepness, and if you stay under 30 degrees (and out of the way of overhead hangfire above 30 degrees), you’re setting yourself up for a safe time.
You have to be absolutely diligent in pre-planning your tour and monitoring during your tour, but with careful attention to slope angles on your route of ascent and descent, it’s perfectly possible to stay out of avalanches’ way.
(Note that this article is for the purpose of discussion and handy information, but nothing replaces professionally taught avalanche safety courses. Look up course offerings in your area and sign up for a new course or refresher!)
Now, back to avy terrain avoidance.
First, get a topographic map that shows slope angles.
So, here’s the fun part. Get a good map that has slope angle shading—Caltopo.com is one of our favorites, but there are many great options. Have a close look at local ski touring zones and trailheads. Looking at the slope angle coloring, you can identify which drainages and hills stay well under 30 degrees for the entire route of ascent and descent. Pay close attention to potential steeper sections and give them a wide berth, avoiding travel under them.
You can get a head-start in your search by asking around for low-angle ski touring in your area. People are likely to toss out great options, and you can then set about doing some detective work to confirm they have low-angle routes of ascent and descent.
Second, get a slope inclinometer (slope angle reader) to use on the go.
Maps are fabulous tools for initial planning. But they can only give information down to a certain level of detail. If the map’s topographic lines represent, say, 50-foot increments, the slope angle shown will be the average slope angle on that increment. There can always be smaller roll-overs and steeper trigger-points that are hard to spot on a topographic map but are completely identifiable in person.
Invest in a simple, inexpensive slope inclinometer (a fancy word for a slope angle reader) and take lots of measurements as you go. Many brands offer easy-to-use inclinometers that take just a moment to use—and they offer invaluable info to guide you as you keep your skintrack firmly on low-angle stuff, then pick a ski descent that does the same.
Third, don’t forget to trust your observations—and your intuition.
If you carefully map your tour and monitor slope angles to fine-tune as you go, you’re on a path to success … and safety. But don’t forget to use your eyeballs along the way. You can quickly notice many neon signs of avalanche terrain, such as wide swaths of mowed-down trees that have been taken out by repeat slides over the years. Gullies are also a big no-no, as are flats beneath steeps where avalanche debris would quickly pile up and deeply bury a person. Sometimes, you can even see actual avalanche crowns where slopes have recently slid. That’s a surefire sign that nearby slopes of a similar elevation, aspect, and angle are untrustworthy.
These visual cues (and other clues, such as whoomphing sounds, wind-affected snow, and stability tests) are all part of your toolkit as you’re out and about, ever-monitoring and assessing if you ought to be where you are.
In summary …
Take an avalanche safety course … then take more to build and refresh your knowledge! It will help you master how to identify avalanche terrain and when it’s safe to go into it. In the meantime, never forget that you can avoid avalanche terrain altogether. Lean on careful pre-trip planning, lots of on-the-go observations, and ongoing education, and you can tour just about any day.
For more avalanche safety tips check out our other blogs on touring safety.
How to read the avalanche report
Avalanche Report Basics
Spring Avalanche Problems and How to Avoid Them
The SheJumps Alpine Development School
Beth Lopez is a seasoned writer and creative director who loves to tell tales of adventure and discovery—and finds writing a powerful way to give a voice to people, causes, and places. Beth runs amok in the Wasatch mountains when untethered from her computer. She believes there’s no such thing as a bad ski day and considers animals her favorite people. Don’t tell her mother about her Instagram mountaineering photos.
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