WINTER HAZARDS

Winter is a place of beautiful extremes, but with snow and ice come unique challenges, too. Winter Mountain Leader Lucy Wallace explains some of the risks, and how to manage them

What’s the key for having a great day out in the winter hills? It’s all about having a great plan in place before you set out. Winter walking is brilliant, but it also exposes us to a whole range of hazards we don’t see at other times of the year.

Knowledge is power. Knowing what potential dangers there are and where they might occur means we can plan to avoid them, by choosing our location or routes based on the risks, not just our ambitions. It is not unusual for conditions to change significantly over the course of a day, so we need to keep assessing the hazards throughout our journey. The experts call this ‘dynamic risk assessment’.

Ice and hard snow

Slippery conditions present a clear hazard to walkers. It’s not just ice on paths; hard, refrozen snow (known as névé) can cover whole mountain sides or lurk in shady gullies. A slip might result in a long, dangerous slide down the mountain. Carrying an ice axe and crampons, and knowing how to use them, is essential.

Avalanches

Avalanches can and do occur in the mountains. They happen when the snowpack moves, and even a small avalanche event can seriously impact our safety. It may be anything from a small slough to a huge, full-depth avalanche running hundreds of metres down the mountainside.

A small slough could knock someone off their feet and move them over rocky ground. Larger avalanches have the capacity to bury people. Significant factors to look out for are heavy snow, high winds, sudden fluctuations in temperature, and pre-existing weak layers in the snowpack.

Statistically, most people who are involved in avalanches in Scotland trigger the avalanche themselves, and these tend to occur in certain places. In Scotland in particular, we are exposed to very windy conditions, so the snow gets ‘re-distributed’ from the windward to the leeward slopes. Gradient is also a factor; avalanches tend to happen on slopes with gradients of between 30 and 45 degrees.

Cornices

Snow builds up on the lee (sheltered sides) of ridges, and on corrie rims. Here we find overhanging ledges of snow called cornices, which can conceal cliff edges and gullies. They can look like solid ground, but are not, making them very dangerous. In poor visibility, they are tricky to spot, so good navigation is required to stay well away from them.

It’s not just about us, either. Cornices are dangerous to people underneath when they collapse, and can even trigger an avalanche on the slope below.

Terrain traps

Typically these are small valleys or deep gullies that avalanches wash into, deeply burying avalanche victims. Some are known accident black spots. An example would be the ‘normal route’ up Buachaille Etive Mor, near the head of Coire na Tulaich, but many other locations also have the potential to become terrain traps.

Poor visibility

Aside from presenting navigational challenges, poor visibility means that mountain hazards are harder to identify. White-out conditions create flat light that conceals changes in terrain and snowpack. Days are short, and you can expect to be starting or finishing in the dark – or both. If visibility is poor, a cautious approach is advisable.

Wind

Powerful winds are common in winter, causing problems for people on exposed terrain, making progress difficult or impossible. Wind chill is energy-sapping, and dangerous if clothing is inadequate. It’s not unusual for conditions to deteriorate rapidly. Wind also moves snow around, scouring some slopes, and depositing snow in sheltered places, raising the avalanche hazard.

Rivers

Whilst rivers can be a hazard at any time of year, in winter they are more likely to be a problem. Heavy rain and snowmelt can make rivers impassable, even washing away footbridges.

By sticking to wind-scoured ridges and easier-angled slopes, we reduce our exposure to avalanche problems