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Rescue teams on a snowy slope work to excavate a lost person.

Keeping an eye on the geography or layout of the terrain can go a long way in helping you stay safe in the backcountry. Photo: Screenshot


The Inertia

Editor’s Note: If you’re interested in learning more about traveling, and riding, safely in the backcountry, check out Sam Thackeray’s Essential Avalanche Awareness Guide here. The Inertia readers get a 100 percent discount with code WELCOME10.


In the avalanche world, there’s no silver bullet. There’s no one thing that’s going to keep you safe out there. But the closest thing we have to that is terrain and learning how to identify and manage your avalanche terrain. You can learn more here or in my new class with Inspire Courses, the Essential Avalanche Awareness Guide.

When you go out into the field, start looking around and start learning what is avalanche terrain and what isn’t.

What Is Avalanche Terrain?

To define that, avalanche terrain includes slopes between 30 and 45 degrees with the prime angle of repose being at about 38 degrees. Not all avalanche terrain is created equal. It’s a very bell-shaped curve with 38 being in the middle and 30 and 45 being on each side of it. So as you work up into that terrain, degree by degree, avalanches are going to want to release closer and closer to that 38-degree slope angle. You’re probably asking, “How do I know what the angle of the slope is?”

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And as humans, we’re really bad judges of slope angle. What you need to do is get yourself an inclinometer, they’re pretty easy to find, easy to buy. You can stand on a slope, set it on a ski pole, place it on there, get a reading. You can use it in profile and hold it up and eyeball it. But this is really the only way to understand and to know and to learn what slope angle is and manage it accordingly.

Snowboard guide Sam Thackeray

Splitboard Guide Sam Thackeray, who works for Payette Powder Guides out of McCall, Idaho

What Isn’t Avalanche Terrain

So we’ve defined what avalanche terrain is, but equally as important is what is not avalanche terrain.

Any slope under 30 degrees is not going to be steep enough to produce an avalanche. Ridges, those high points are going to be good, safe places. And along with that, nice wide valleys or meadows – you’re not going to have an avalanche problem there.

Even if we decide that on any given day it’s safe and we can go out and go ski in avalanche terrain, it’s best to always travel out of avalanche terrain. In the backcountry, we spend 80, 90 percent of our time walking around and getting to the slopes that we want to go ski. At some point, it just becomes a numbers game.

Of course, there are a few caveats with those pieces of terrain.

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Things to Look Out For When Defining Avalanche Terrain

Ridges — we always need to be very aware and cognizant of cornices. They’re extremely unpredictable and can break a lot further back than you expect. So give cornices a wide berth of respect.

For traveling on slopes less than 30 degrees, we want to make sure that we don’t have avalanche terrain above us that could potentially run down onto that slope that we’re on.

In that same vein, if we’re traveling through meadows or wide valleys, make sure we’re not traveling through the run-out of those avalanche paths.

Avalanche Terrain Definitions

So when we’re looking at terrain, we break it down into three large categories. The first one being Simple Avalanche Terrain. These are slopes that have a lot of good, safe options to take a safer route, lower angle terrain so that you don’t have to commit yourself or your whole group to avalanche terrain. They’re going to tend to be smaller and without terrain traps.

That second middle ground is Challenging Avalanche Terrain. You’re moving into larger avalanche paths, more well-defined. Fewer safer, or less-exposed options to get out of that terrain if you don’t like what you’re seeing or deem the situation to be unsafe.

The third one is Complex Avalanche Terrain, where you’re going to have few, or basically no, options to take less-exposed routes. You’re going to have overlapping avalanche paths to where if you trigger one, another could potentially come down into that same deposition zone.

These are really broad brush strokes, but it’s important to understand that not all avalanche terrain is created equal.

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Editor’s Note: If you’re interested in learning more about traveling, and riding, safely in the backcountry, check out Sam Thackeray’s Essential Avalanche Awareness Guide here. The Inertia readers get a 100 percent discount with code WELCOME10.

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