Dangerous avalanche conditions in the Alps warn experts

Posted by Sarah Stirling on 23/02/2017

Sarah Stirling talks to British and Swiss avalanche experts to find out why ski touring and ice climbing is particularly dangerous in the Alps at the moment, and how you can stay as safe as possible.

Our winters are going weird

Trump may doubt climate change, but perhaps that’s because he doesn’t ski tour or ice climb. When it snowed buckets in mid-November last year, hopes were high. Although it was weirdly early, at least the season seemed to be getting off to a better start than it had the previous few years.

Remember 2014? The first big snowfall of the season was followed by three weeks of cold and blue skies. When snowfall was finally predicted the week before Christmas, instead of celebrating, mountain gurus prophesied ‘avalanche carnage’ and a dangerous winter season ahead. They were right.

At the time, French avalanche expert Alain Duclos told me: “We’ve not seen these kind of conditions for a number of years across the Savoie and Hautes-Alpes.” Then, in 2015, it happened again.

This time the first dump of the season was followed by nothing for two months. Accommodation operators in the Alps were faced with glum customers over Christmas and New Year. Then, finally, there was loads of snow, and the season kept going until June.

This season, we are still waiting for another big dump of snow, and it’s now February. There was no snow for two months after that first dump in November. Christmas and New Year were barren once again Then 70cm fell. Then nothing for another two weeks. Then 70cm.

WATCH: Avalanche and route assessment on the approach on BMC TV

I remember my first full winter in Chamonix in 2012. The snow started promptly on the first of December, and kept reliably dumping all season. I asked Director of Chamonix’s Avalanche Academy, Stuart MacDonald, is this climate change, or have there always been crops of bad seasons like this?

He told me: “There have always been crap seasons. But they're much more common now than they used to be. This could just be a blip, but it seems unlikely.”

Dangerous conditions

The issue is, as well as poor skiing conditions, the lack of snow results in much more dangerous conditions, too. When the season starts with a dump of snow, and then nothing follows for ages, the result is a shallow snowpack. This means there's a steep temperature gradient between the ground and the surface of the snow.

Glassy, straight-edged and fragile faceted snow crystals commonly form under these conditions. It results in the kind of snow that doesn’t easily form snow balls. “Faceted snow crystals don’t bond to anything easily,” explains Stuart. Imagine what happens when new snow sits on top of this weak layer.

The Swiss Institute for Snow and Avalanche Research are Europe’s leading experts in the complex field of snow science. Dr Kurt Winkler, an avalanche forecaster on their team, told me: “We have this persistent week layer, especially in the intra-alpine regions of Valais and Grisons (the ‘orange’ spots on our danger map), including the whole Engadin.

WATCH: Winter skills: Conditions and weather on BMC TV

“This problem mostly exists on west to north to east-facing slopes between 2,000m or 2,200m up to maybe 2,800m. The problem is not as obvious as it was one or two weeks ago, but still we have some releases of dangerously large avalanches, often remotely triggered, and sometimes over larger distances.

“Without noteworthy precipitation, the problem will diminish over the next weeks, but very, very slowly. On these aspects and regions the situation will rest treacherous for a long time. What would help would be a lot of new snow to make the situation more dangerous for a short time and bury the week layers deeper into the snowpack. Unfortunately, huge precipitation is not predicted in the near future.”

One of the greater dangers here is public perception. Most average off-piste skiers know that it’s dangerous right after a heavy snowfall, but time stabilises most snow packs if there’s not much wind or new snow. However, this year the weak snow layer could once again persist to the end of the season in some areas of the Alps, making snow conditions much more difficult to assess accurately and safe terrain less predictable.

Current conditions in Chamonix

“I was out on Monday ski touring around Les Contamines and the wind has distributed the snow in all sorts of weird and unpredictable ways,” Mountain Guide Andy Perkins told me. “We skied powder on a south facing slope, and then facets on both east and west facing aspects. The day before in Megeve just over the hill, there was a fatal avalanche incident on a west facing slope.

“So each slope needs assessing on a case by case basis, now more so than ever as the regional prediction of considerable avalanche danger is just that: regional. There are slopes very unlikely to release and some that are highly unstable, and it takes an experienced eye to spot the difference. If in doubt, be conservative and stay on slopes less than 30 degrees.”

While avalanches are a complicated, inexact and often unpredictable science, the well-known formula ‘new snow over a weak layer on slopes more than 30 degrees’ really works very well [i.e. is avalanche prone].

WATCH: What to pack when heading into Backcountry on BMC TV

Stuart MacDonald, who regularly digs snow pits to examine the different layers forming, commented that, between 2,000m and 800m, on shady slopes that are north-west to north-east facing, there’s a weak sub layer that is going to stay there for quite a while. That’s because those slopes stay cold. “If you dig on those slopes you’ll find some really sugary snow down at the base.”

“The best thing would be a big dump to bury it, but there’s nothing like that on the radar, so it’s going to stay there,” he told me. “Is it safe to go off-piste? If you go to the right places, i.e. slopes that get a reasonable amount of sun, and slopes which are above and below those elevations.

“We probably had this problem on other aspects earlier in the season, but because they get more sun, with the warming it’s melted out now and bonded together. If we’d had lots of snow early season we’d have had a deeper snowpack from ground at steady zero to the surface not get this faceting.”

Stuart pointed out that last week, six people were killed while ice climbing in the Alps, in Italy and France. “It’s warm, more like spring than winter,” he told me. “People are climbing ice falls because it’s winter, and that’s what you do, but there have been some collapses due to melting ice. Perhaps people are not paying attention to the unusual conditions.”

Tips from the experts

Stuart Macdonald: Always go off-piste fully equipped with shovel, probe, transceiver and know how to use them. Always read the avalanche bulletin and learn how to plan your day properly to minimise avalanche risks. As the level of risk increases, reduce the angle you ski.

Alain Ducros: Be especially cautious to avoid remote triggering. i.e. as well as avoiding slopes more than 30° as much as possible, be wary of the bottom of those slopes. Learn how to recognise a typical weak layer and how to measure 30° in the field.

Andy Perkins: Be particularly wary of slopes steeper than 30°, slopes facing north through east when it’s cold, slopes facing south through west when it’s warm and lee slopes after wind-loading effect.

WATCH: How to put on skis when it's steep on BMC TV

Kurt Winkler: Consult the most up-to-date avalanche forecast at www.slf.ch or with the phone app ‘Whit Risk’ (also available in English). Take extra caution on steep, shady slopes in little-frequented backcountry terrain, especially for several days after the last really big snowfall.

Recommended reading for off-piste skiers: Staying Alive in Avalanche Terrain by Bruce Tremper.

The BMC's Off-Piste Essentials DVD in association with The National Mountain Centre at Plas y Brenin contains essential skills and techniques for back country skiing, ski touring and ski mountaineering - inlcuding avalanche awareness.

WATCH: The BMC Off-Piste Essentials trailer on BMC TV


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