I was lucky enough to be able to go backcountry skiing in Colorado just a few weeks ago. The fresh powder is spectacular, but comes with high risks. Avalanches are frequent in the Colorado back country, so it is important to have at least a basic understanding of how they form before you venture out of resort territory.
- Many factors influence the likelihood and severity of an avalanche, temperature, snowpack, wind, and terrain being the main ones. Snowpack is essentially defined as the various layers of snow that build up over the season. You can have icy layers, crystalized layers, or soft layers, which all build up on top of each other. This becomes an issue when say, a heavy layer builds up on a softer powder layer, on top of an icy smooth layer. This can lead to the formation of avalanches when top layers crack and begin to slide on icier bottom layers.
- Wind can help to displace snow from one side of the mountain to the other. This leads to wind slabs, where large amounts of snow can build up on this top layer, displaced by the wind, and increase the likelihood of an avalanche.
- Of course, another avalanche factor is steepness of the slope. Most avalanches occur on an incline of about 30-45 degrees.
- Temperature is the final important factor in forming avalanches. High temperatures cause the snow to melt, allowing water to trickle down lubricating the lower snowpack. It also makes the snow heavier, less fluffy, leading to slabs breaking away and starting avalanches. On the other hand, however, very cold temperatures cause water to evaporate out of the warmer snowpack and freeze on the surface, forming weak crystalline structures called surface hoar. Surface hoar serves as a weak layer of snowpack, so as that snowpack builds up on the surface hoar layer, it tends to break away much easier.
So there you go, that is the basics of avalanches. Before you go out and ski the backcountry, it is important to understand the conditions at the time. Check your local avalanche report (most states with backcountry skiing have them) and make sure to stay safe and make good decisions.
- Many factors influence the likelihood and severity of an avalanche, temperature, snowpack, wind, and terrain being the main ones. Snowpack is essentially defined as the various layers of snow that build up over the season. You can have icy layers, crystalized layers, or soft layers, which all build up on top of each other. This becomes an issue when say, a heavy layer builds up on a softer powder layer, on top of an icy smooth layer. This can lead to the formation of avalanches when top layers crack and begin to slide on icier bottom layers.
- Wind can help to displace snow from one side of the mountain to the other. This leads to wind slabs, where large amounts of snow can build up on this top layer, displaced by the wind, and increase the likelihood of an avalanche.
- Of course, another avalanche factor is steepness of the slope. Most avalanches occur on an incline of about 30-45 degrees.
- Temperature is the final important factor in forming avalanches. High temperatures cause the snow to melt, allowing water to trickle down lubricating the lower snowpack. It also makes the snow heavier, less fluffy, leading to slabs breaking away and starting avalanches. On the other hand, however, very cold temperatures cause water to evaporate out of the warmer snowpack and freeze on the surface, forming weak crystalline structures called surface hoar. Surface hoar serves as a weak layer of snowpack, so as that snowpack builds up on the surface hoar layer, it tends to break away much easier.
So there you go, that is the basics of avalanches. Before you go out and ski the backcountry, it is important to understand the conditions at the time. Check your local avalanche report (most states with backcountry skiing have them) and make sure to stay safe and make good decisions.