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Tips for Avoiding Avalanches

by Robyn Gordon

Slopes < 30 degrees

Remember that virtually all avalanches release on slopes of 30 degrees and steeper. You can effectively avoid avalanche terrain by staying on slopes of less than 30 degrees.

Slopes > 30 degrees.

37 degrees is recognised as a killer slope. It has the slope for speed and the quantity of gathered snow to be powerful.

If you are planning to tackle steeper terrain, here are a few safety reminders:

  1. Carry and know how to use avalanche rescue gear. You should not be skiing or climbing potential avalanche slopes without having beacons, shovels, and probes.
  2. Only one person in a group should be exposed to potential avalanche danger at a time.
  3. Climbing, skiing, and riding down the edge of slopes is safer than being in the centre.
  4. Snow stability changes from day to day and hour to hour. For example, a large spring storm, or a sustained period of hot weather can increase the avalanche danger. During a storm, or immediately after, new snow may not bond well to the icy old snow surface. Also, soon after a storm, several hours of bright sun can warm the surface snow enough to become unstable. However, after a couple of days, the new snow will strengthen and ease the danger.
  5. Watch temperatures closely and monitor the snow pack for free water. When you can begin to wring water out of a fist full of snow, it is time to move to more gentle terrain, less than 30 degrees in steepness. Beware of overnight temperatures that do not get below the freezing level, or barely get below freezing for just a short time. When this happens the danger for wet snow avalanches increases earlier the following day. Usually you have little risk when you ski early in the morning when the snow surface is crusty, or just beginning to soften. The danger begins to rise with thaw conditions late in the morning through the afternoon.
  6. Hoar frosts or a long period of frosty mornings creates an unstable layer. This layer will remain in the snowpack for weeks/ months.

Big cornices may last well into the summer. To be safe, avoid travelling under cornices when the snow turns wet or when water starts to drip from the cornices.




Robyn Gordon
Robyn Gordon

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Also in EDUCATIONAL RESOURCES

About avalanches

by Robyn Gordon

Why Worry About Avalanches?

Snow avalanches are a natural process, occurring perhaps 1,000,000 times per year, world-wide. They are one way for snow on an incline to adjust to the pull of gravity. The vast majority of these slides are not a problem, because an avalanche, in and of itself, is not a hazard. A person (or a person's belongings) has to get involved in order for there to be a problem.

So, who gets caught in avalanches?

 

What happens if you get caught in an avalanche?

 

The fact is, that avalanches don't drop from the peaks onto the heads of unsuspecting innocents with the unpredictability of a plummeting meteorite. 95% of people who are caught in avalanches are caught by a slide that was triggered by themself or a member of their party.

I think this is good news! Our behaviour creates the hazard, so we can change our behaviour to avoid problems.

Avalanche Characteristics

There are many different types of avalanches, but the one that worries us the most is the "slab" avalanche, in which a mass of cohesive snow releases as a unit. This type is easily recognized by its distinct crown and flanks (click for a diagram of the nomenclature associated with avalanches).

Slab and other avalanches can be hard or soft, wet or dry and can be triggered naturally or artificially.

Spotting Avalanche Hazard: The Avalanche Triangle

Some places have avalanches: Switzerland's Alps, Utah's La Sals, Nepal's Himalayas, New Zealand’s Mountains. Some places don't: South Viet Nam, the Mile-High Stadium, your living room (the distinctions are not always so obvious, unfortunately).

Why is this? Avalanches are formed by a combination of three things that together are known as the "Avalanche Triangle". These 3 ingredients may be present in one location but absent 10 feet away. The three legs of the triangle are Snowpack, Terrain and Weather.

Detecting Instability

There are many tip-offs to the presence of a potential avalanche, including surface clues and active stability tests. You should never trust a single information source--stability evaluation is an ongoing process!

The information from this page originates from www.avalanche.org.

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New Zealand Avalanche resources

by Robyn Gordon

Mountain Saftey Council (MSC) New Zealand

The Mountain Safety Council is an important advocate of outdoor safety in new Zealand. They have an excellent brochure on avalanches, how to recoginise danger and how to prevent them. Their website has further resources available that you might want to explore. It also contains saftey tips for in summer time.

MSC also runs a website with backcountry avalanche advisory which is provided as a public service. It is intended as an advisory only.

Avalanche forecasting is an undertaking which requires extensive study and field observations. Those endeavouring to travel in the Southern Alps and the mountains of the North Island, do so at their own risk. We recommend winter travellers be well informed about current weather, snowpack and avalanche hazards.

Winter travellers should not travel alone. All members of your party should wear a transceiver (457khz) and know how to use it. In addition everyone should carry a shovel, and a probe. Winter travellers should advise someone where they are travelling, and when they will make next contact.

Department of Conservation (DOC)

The Department of Conservation can assist with safety advise. Check their website for more details.

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Risk Management

by Robyn Gordon

Before teachers take classes on snow trips they should have all students fill out a risk assessment forms. This is called risk management.

The forms help to identify all of the possible risks that may occur during the trip. The next step is then to work through scenarios how the grooup will respond in case one of the scenarios happens. Each of the scenario's should be worked through to make sure they have the right equipment, first aid, support systems, and procedures in place before they go.

They are then prepared for every possibility.

The Avalanche Lady covers risk management in her speech and can help school groups with providing the risk assessment forms.

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