Mountain Safety

Learning where, when and why avalanches occur can help you gather information and make observations to minimize your chances of getting caught in a slide. For an avalanche to occur, you need three things to happen:

1. Unstable snow
2. Avalanche terrain
3. A trigger - natural forces (such as wind) or human-induced (such as a person's weight traveling over weak snow)

Remove one of these three factors and the chance of an avalanche is none. For example, if you have unstable snow and you are the potential trigger, you can't have an avalanche if you're not in avalanche terrain. If the snow is unstable but you're in a flat or low-angle area (not in avalanche terrain), there's no risk of avalanches.

Use the following three questions as a guide to help you decide where and why an avalanche can occur:

1. Is the snow unstable and where is it unstable?
Unstable snow is snow that wants to or can slide downhill. Weather, precipitation, temperature, wind, sun and many other factors influence snowpack stability. While it takes more formal training and experience to understand and analyze snowpack conditions, there is one easy way to get this information: Read the avalanche forecast to find out whether the snow is unstable and where.

Avalanche forecasters and other professionals make field observations and analyze the snowpack and weather over the season to help you make decisions about when and where to go. These forecasts alert you to avalanche dangers and explain the types of problems you might expect.


2. Am I in terrain where avalanches can occur?
Recognizing avalanche terrain (where they occur) is a key to traveling safely in the backcountry. Avalanche terrain is anywhere an avalanche can start, run or stop. Learn to recognize such terrain to help you plan a trip and pick a safe route.

Consider these factors when deciding whether you're in avalanche terrain:


• Steepness of the slope:
A slope has to be steep enough for snow to slide. Most avalanche activity typically starts on slopes between 30 and 45 degrees. Some slides can happen on lower angles but they're not common. As you travel in the backcountry, ask yourself whether the slope is steep enough for snow to slide. It can be hard to estimate slope angle; a slope meter (inclinometer) is a useful tool to measure slope angle quickly. (Practice using a slope meter at a ski resort or elsewhere before traveling into the backcountry.)


• Connected slopes:
Avalanche terrain is anywhere an avalanche can start, run and stop. If you're traveling in more gentle terrain but it's connected to steeper slopes above you that can slide, there's still a risk of an avalanche.


• Terrain traps:
these are features like gullies, rocks, cliffs, trees or crevasses that can magnify the consequences of an avalanche. If you get caught in an avalanche, terrain traps will make even a small slide worse because they increase the risk of injuries or make it more challenging to dig someone out. A small slide can cause traumatic injuries if it barrels you into hard objects such as trees or rocks, sends you off a cliff, or buries you deeply in a gully or depression. Most people who die in avalanches do so from asphyxia (typically because they're unable to breathe when buried) or trauma.


3. Can I trigger an avalanche?
The third factor needed for an avalanche to occur is a trigger. Natural triggers such as snow, wind or rain can cause avalanches. But most avalanche accidents are triggered by the subsequent victim or someone in the victim's group. A skier, snowboarder, snowshoer, snowmobiler, climber and others can all trigger avalanches (such as by moving their weight over unstable snow). So the decisions you make about when and where to go and how to travel can make a huge difference in preventing accidents. And despite a prevailing myth, you cannot trigger an avalanche by shouting or making loud noises.

Recognize Five Red Flags

Additionall to reading the daily avalanche forecast, make sure to keep your eyes open for avalanche red flags. These are the simplest and most basic observations you can make to stay safe when navigating the backcountry. Be on the lookout for visual and audible queues of increased avalanche danger. If you see one of these red flags, it is natures way of telling you the snowpack is unstable and there is a real risk of avalanche.
Here are five red flags of unstable snow:

1. Recent Avalanches:
If you see signs of recent avalanches or forecasters tell you there have been recent slides, it's a clear warning to avoid avalanche terrain. If you can't tell whether an avalanche was recent, assume that it was. One clear sign of a recent avalanche: if you see piles of chunky snow (avalanche debris). Or if you look up at the mountains, you'll see the vertical face (called the crown or fracture line) where the avalanche has pulled away from the snowpack.

2. Shooting Cracks:
When unstable snowpack collapses under a trigger, cracks may shoot across the snow surface and can sometimes run for tens or hundreds of feet.

3. "Whumpfing":
This is the loud noise you may hear when unstable snowpack collapses under you or your group. As the air rushes out of the snowpack, it goes "whumpf." (Yes, that's the technical term adopted by avalanche forecasters and educators). Where shooting cracks are the visual clues, whumpfing is the audible one. The two can happen at the same time.

4. Big Changes in Weather:
If you're experiencing big changes in weather, you should expect big problems.
• Recent rain or heavy snowfall means the conditions are there for unstable snow.
• Strong winds: Look for surface patterns on the snow made by strong winds, which could indicate that snow has been transported and deposited in dangerous drifts that can release and run. Pay attention to cornices and drifts on steep slopes.
• Rapid temperature change: Beware if you experience rapid melting, which can affect snowpack stability.
5. Persistent Slab Avalanche:
This is a type of avalanche that forms when a weak layer of snow is buried by other layers of snow. While most avalanches occur during or after a storm, persistent slabs can occur long after a storm has ended and are disproportionately responsible for avalanche fatalities.

No matter what precautions you take, consider an avalanche education program. Using these five rules can grealty increase your safety when in the backcountry, but a course is always the best way to learn about avalanche safety.