As we get into spring, more and more of us are getting antsy to get out into the outdoors, and into the mountains. With the high amount of recent snowfall in the area, the threat of an avalanche is very possible. All it takes is a warm day, a windy day (which we never have!), or more new snow on top of less stable snow. Most of us do not have or can't afford beacons so we are at the mercy of our training and our knowledge of what to look for. Even during spring bear season, which is coming upon us, I have seen small avalanches in areas that I would hike over in a second. It's just not the mountain climbers who need to be aware, the cross country skier, the snow-shoe enthusiast, the shed hunter, and anyone else who takes weekend trips to the hills in the spring. The following information, mostly taken from National Snow and Ice Data Center, will give you a nugget of information about avalanche safety. Please take a moment to read this and apply it to your memory bank.
Keep the wind at your back, and your eyes above the skyline,
Although avalanches can occur on any slope given the right conditions, in the United States certain times of the year and certain locations are naturally more dangerous than others. Wintertime, particularly from December to April, is when most avalanches will "run" (slide down a slope). However, avalanche fatalities have been recorded for every month of the year. The highest number of fatalities occurs in January, February and March, and April when the snowfall amounts are highest in most mountain areas. A significant number of deaths occur in May and June, demonstrating the hidden danger behind spring snows and the melting season that catches many recreationists off-guard. During the summer months, it is often climbers who are caught in avalanches. In the United States, 514 avalanche fatalities have been reported in 15 states from 1950 to 1997.
Slab avalanches are the most common and most deadly avalanches, where layers of a snowpack fail and slide down the slope. Since 1950, 235 people in the U.S. have been killed in slab avalanches. Hard slab avalanches involve large blocks of snow and debris sliding down a slope. In soft slab avalanches, the snow breaks up in smaller blocks as it falls. An avalanche has three main parts. The starting zone is the most volatile area of a slope, where unstable snow can fracture from the surrounding snow cover and begin to slide. Typical starting zones are higher up on slopes, including the areas beneath cornices and "bowls" on mountainsides. However, given the right conditions, snow can fracture at any point on the slope. The avalanche track is the path or channel that an avalanche follows as it goes downhill. When crossing terrain, be aware of any slopes that look like avalanche "chutes." Large vertical swaths of trees missing from a slope or chute-like clearings are often signs that large avalanches run frequently there, creating their own tracks. There may also be a large pile-up of snow and debris at the bottom of the slope, indicating that avalanches have run. The runout zone is where the snow and debris finally come to a stop. Similarly, this is also the location of the deposition zone, where the snow and debris pile the highest. Although underlying terrain variations, such as gullies or small boulders, can create conditions that will bury a person further up the slope during an avalanche, the deposition zone is where a victim will most likely be buried. Several factors may affect the likelihood of an avalanche, including weather, temperature, slope steepness, slope orientation (whether the slope is facing north or south), wind direction, terrain, vegetation, and general snowpack conditions. Different combinations of these factors can create low, moderate or extreme avalanche conditions. Keep in mind that some of these conditions, such as temperature and snowpack, can change on a daily or even hourly basis. This necessitates constant vigilance of your immediate surroundings while doing any wintertime backcountry travel. The route you chose may be safe when you begin, but may become dangerous if conditions change dramatically throughout the day. While this may seem like a lot of work, once you understand factors that can cause avalanches, most of these signals require simple observation to evaluate your surroundings as they change. Simply ask yourself, when are conditions sufficient to cause a mass of snow to slide down a slope?
If you are caught in an avalanche yell and let go of ski poles and get out of your pack to make yourself lighter. Use "swimming" motions, thrusting upward to try to stay near the surface of the snow. When avalanches come to a stop and debris begins to pile up, the snow can set as hard as cement. Unless you are on the surface and your hands are free, it is almost impossible to dig yourself out. If you are fortunate enough to end up near the surface (or at least know which direction it is), try to stick out an arm or a leg so that rescuers can find you quickly. If you are in over your head (not near the surface), try to maintain an air pocket in front of your face using your hands and arms, punching into the snow. When an avalanche finally stops, you may have only a few seconds before the snow sets up and hardens. Many avalanche deaths are caused by suffocation, so creating an air space is one of the most critical things you can do. Also, take a deep breath to expand your chest and hold it; otherwise, you may not be able to breathe after the snow sets. To preserve air space, yell or make noise only when rescuers are near you. Snow is such a good insulator they probably will not hear you until they are practically on top of you. Above all, do not panic. Keeping your breathing steady will help preserve your air space and extend your survival chances. If you remain calm, your body will be better able to conserve energy.
Following is a list of quick checks you can make throughout the day:
-What have the weather conditions been over the past few days? Recent heavy snows?
-Can you observe any wind loading on the slopes?
-Do you have a good sense of the snowpack? Have you performed any snowpit or shear tests?
-Have you noticed many fracture lines, heard "whumping" or cracking sounds, or hollow noises in the snowpack?
-Are you keeping an eye on the orientation and steepness of the slopes as you cross them?
-Are you lingering in gullies, bowls, or valleys?
-Noticed any recent avalanche activity on other slopes similar to the one you are on?
-If a slope looks suspect, are there alternative routes?
Extra precautions to take
-If there is no alternative to crossing a suspect slope, do so one person at a time to minimize risk.
-When descending or ascending a slope, try to stay as far to the sides of a potential avalanche chute as possible to decrease your chances of being caught if an avalanche runs.
-Be aware of the condition of those in your party. If someone is tired, hungry, or cold they may not be using their best judgement.
-Remain constantly aware of changing weather or temperature conditions, particularly if your outing will last more than a few hours.
-Consider avalanche rescue equipment, such as beacons, ski-pole probes, and collapsible shovels, as a necessary part of your backcountry gear.
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