General Interest

Caught in an Avalanche

Although overshadowed by the severe weather in France & Spain on the 24th January, there was a dramatic mountain rescue attempt in Scotland that same day, when a major rescue operation found three climbers who were lost after an avalanche on the Highlands mountain Buchaile Etive Mor near Glencoe. Though the climbers were taken to hospital in Fort William in a serious condition they all sadly died later, from the effects of the avalanche.

Avalanches are more common in this country than you might imagine, as we often see the kind of conditions that precipitate them. With the popularity of winter climbing and off piste skiing greater numbers are at risk and each year people are killed or injured in the UK by them. Quite often though such accidents are avoidable, if those involved had been more careful & understood the risk better. For this reason the Scottish Avalanche Information Service (SAIS) exists to help warn of potential avalanche hazards. Its' website is at http://www.sais.gov.uk/

If you plan to go winter mountain trekking, off piste skiing or climbing, avalanche hazard considerations should always be part of your daily preparation planning, making sure you check both forecast snow and weather conditions, in respect to such a hazard. Avalanches may occur whenever there is snow lying on the mountain side at a sufficient angle. They occur regularly here in the  Lake District , the Cheviots, the Pennines and north and central Wales- so its not just Highland Scotland that is at risk.

If you are trying to make an assessments of the hazard, the bottom line is that there no substitute for the gut feeling for snow conditions you acquire after years of mountain walking experience. However, newbies can still have a safe time if they learn the basic signs of risk -and then act on them!

There are different types of avalanche - when one snow layer slides over another its called a 'Surface Avalanche'; if the snow layer slides over the ground it is called a 'Full-Depth' avalanche. It can be dry or wet depending on how much water is present in the snow; can be of loose powdery snow or may be a more compact 'slab' of snow, a type of avalanche which occurs when an area of cohesive snow separates from its surrounding snowpack and slides down en masse.

So how should you best avoid getting in the way of such an event? Well, it's complcated and the best idea is probably to study the SAIS website's excellent guidance to start with (see http://www.sais.gov.uk/avalanche-awareness.asp ). In a few sentences though you know how to read the signs. These include monitoring the weather, as many weather conditions affect avalanche risk- so get information before you set out. Use local advice and ring the forecasts available from pre recorded telephone advice lines (see below) but above all factor in the chance of unexpected changes in weather. When you're about to arrive there look at the snowpack- is there any evidence of recent avalanche activity, any fresh loading of new snow on old? What's the state of the snow like? You can dig a snowpit if you like to test it. Dig down to the first reasonably thick layer of older re-frozen snow and check the hardness of it. The more compact it is generally, the better. Very soft layers, layers of ice, hail layers or air spaces are all signs of potential trouble however.

The web site above offer many techniques that will help you to make a reasonable hazard assessment. If you think the snow
is only marginally safe don't risk it!

Here then are the key warning signs that spell 'Trouble', as detailed by the SAIS;

• If you see avalanche activity on the slope where you intend to go, go somewhere else.
• If there rapid slab or new snow building up at more than 2cm per hour it may produce unstable conditions more than 30 cm build up is very hazardous. Get off the slope immediately.
• If when you do a snowpit test you find slab snow lying on ice or neve, leave the area.
• If you find a discontinuity between snow layers, caused by loose hail pellets or an airspace, leave the area.
• If there's a sudden temperature rise - risk increases as the temperature rises, even if it's still below freezing
• If it feels unsafe - the "seat of the pants" feeling of the experienced observer deserves respect.

Remember that on most mountains in the UK, an avalanche hazard can be avoided by a sensible choice of route.