Avalanche safety: What to look for on the slopes
Whether you are riding down a backcountry face after a day of hiking, or catching some fresh powder after snagging the first chair up at a resort, learning to spot avalanche terrain is a skill that could save your life.
And while some think only trained snow specialists can spot avalanche danger, a little common sense can go a long way.
Blane Smith, Executive Director of the Alaska Avalanche School, likened looking for avalanches to finding bear prints in the mud; you generally stop and survey the situation to see if you are in danger of being attacked, especially if your senses pick up on other signs that might lead you to think a bear is present, like a salmon stream near by or high brush the bear could be hiding in.
“Avalanches are the same way; they’re not mysterious at all, and they have tracks,” Smith said. “Just like you assess the risk of bears you can use the same intuitive skills to assess avalanche risk.”
Before setting foot, ski or board on a questionable slope, Smith said the question to always ask yourself is, “is this slope steep, smooth, leeward and loaded?”
If it is, then get off.
The first thing to consider when looking at a slope is how steep it is, asking yourself “Is this slope capable of producing an avalanche?”
According to Smith, an avalanche can occur on a slope upwards of 25 degrees, with the most dangerous “red light terrain” existing between 30 and 45 degrees ” not so steep that snow sluffs off but steep enough to be easily triggered.
The next aspect to consider is how smooth the slope is. For this you will need to look at signs that point to what’s going on under the snow.
When the term smooth is used in this sense, Smith said it means there is very little on the slope that will act to anchor the snow in place, like trees and rocks. For the slope to be “rough” enough to lower the risk of an avalanche, trees need to be so thick you cannot ski through them and rocks need to be exposed and in abundance.
But while most skiers and riders are not looking for impassable tree or rock lines to ride through, another thing to determine is if the slope you plan to ride is on the leeward side of the mountain.
Avalanching isn’t just a product of how steep the slope is, it’s also about how much stress is imparted on the slope ” more snow equals more stress.
“Wind can transport snow from the windward side of slope to the leeward side at rate 10 times greater than it can fall from the sky,” said Smith.
According to Smith, cornice areas are an easy indicator of a leeward side of a mountain. Sometimes, however, signs are more subtle, like scouring, wind texturing, and loading on leeward sides.
But as the wind blows and the snow rapidly accumulates on leeward aspects, that building of stress leads to the slope being loaded, or at a point of maximum stress.
And at this point, all the slope needs is a trigger.
“The avalanche is looking for a trigger,” said Smith. “It doesn’t care if it’s a natural trigger, like more snow or a cornice fall, it’s just looking for a trigger. And we want to make sure we’re not that trigger.”
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