How steep is 27°? 

Lots of people think that of zones that are under 27 degrees as being boring or too gentle to have fun. However, I don't believe this to be the case, and in fact, I have lots of great memories skiing slopes under this threshold. While I would agree that these slopes are far from being extreme. By using a level app on your phone, you can see for yourself that the exact angle is still a moderate pitch that is roughly equivalent to a blue trail at a resort. For this reason, if I’m not 100% confident in the stability of the snowpack, I find that often it is not worth it to risk skiing steeper terrain.

Not every slope under 27° is safe from avalanches!

Here is my checklist that qualifies a slope as non-avalanche terrain.

If the zone answers "no" to each of these questions, then it is safe from avalanches.

• Look from afar: Is the slope over 27°?

• Look closely: are there any spots within the zone that exceed 27°? Even just for a small section? 

• Look above: Are there slopes above the zone that exceed 27°? 

• Look left and right: are there slopes connected to the zone that exceed 27°?

• Look before and after: Do you have to ski through or below any terrain that exceeds 27° to get into or back from the zone? 

Here is an example of a skier on a slope that is under the 27° threshold but is still exposed to avalanches from the steeper slopes above.

To avoid exposure to avalanches, staying in the green area would have been a much better choice. In the green area, the slope angle is more consistent staying under 27° all the way to the ridge. 

It is important to know that in some conditions, it is possible to remote trigger an avalanche from far away from the start of the slide. 

In this example, the additional weight of the skier could be enough to trigger an slide starting in the steeper section above (highlighted in red). If this happened, both the skier and the photographer would have a high chance of being buried.

A Note on Trees:

Dense trees are often cited as a feature of a slope that prevents avalanches. The argument is that if the trees are close enough together, they will support the snowpack and prevent large slabs from sliding. 

While this is factually true, in practice, relying on trees to prevent avalanches is trickier than it sounds. The main problem is that once the tees get spaced out more, they can actually weaken the snow pack and act like perforations in the snow. 

In fact, looking through avalanche accident reports, lots of avalacnche gets triged within forested areas. When looking at a slope, both in person and on satellite maps, it can be hard to tell how consistently dense the forest is, and it only takes one larger gap in the trees to trigger a slab large enough to bury a person. For this reason, I generally do not use tree density as a factor to qualify a slope as non-avalanche terrain. 

Test Yourself: