Category: Snow Conditions

January looks like being one of the worst months ever for avalanche fatalities amongst off piste and backcountry skiers. It looks like around 40 people will have lost their lives in avalanches in the Alps this month alone – usually the fatalities for the entire season are about 100, so this year is on track to be one of the worst. The distinction for the wordt season ever currently stands with 147 avalanche deaths in 2017/18.

From a meteorological and snow science perspective, the 2025/26 season has been the perfect storm of dangerous conditions. Experts are calling it a “once in a two-decade” phenomenon.

The disaster was seeded back in late autumn. After a cold, dry spell, the initial snowpack didn’t consolidate properly. Instead, the snow crystals transformed into a loose, sugary layer called “persistent weak layer” (or depth hoar). During January fresh, heavy snow landed directly on top of that fragile, sugary base layer.

This is where the science meets human nature. You noted the majority of victims are off-piste and backcountry skiers. Reports suggest 90 to 95% of fatal avalanches are triggered by the victims themselves .

The deep, fresh powder that skiers crave is the same snow that is dangerously unstable. creating a terrible paradox:

• Ignored Warnings: Despite high-risk warnings, many experienced skiers ventured into closed or unprotected areas .
• The Herd Instinct: Experts note that seeing other tracks in the powder distorts risk perception. Skiers follow others into dangerous terrain, assuming it must be safe .
• High Traffic: After recent snowstorms, more people than usual headed into the backcountry, increasing the statistical chance of accidents
• Increased Popularity of Back Country Skiing: Many piste skiers are taking up ski touring as it is seen as ecologically more attractive than skiing on piste with all its mechanical equipment and snow cannons.

It’s a stark reminder that in the backcountry, nature, not the skier, is always in charge.

The rise of artificial snow is inexorable. In 2009 about a fifth of slopes in the French Alps were supplied by snow-machines. Today it is over half, and rising fast. In some resorts in America the artificial takeover is nearly total. According to International Ski Federation rules, it would now effectively be impossible to make competition-grade slopes without using artificial snow.

An article in 1843 magazine provides the following explanation of what artificial snow is:

Snow machines take water, mix it with compressed air and blast it into a mist of tiny droplets that freeze into hard balls of ice as they fall to the ground. Under a microscope, these look nothing like snow crystals. They’re just lumpen spheres crammed together like misshapen Maltesers. Snow machines have two big advantages beyond the obvious: creating snow when none is falling. First, artificial snow is about 50 times harder than the real stuff, which makes it far less likely to melt. Compared with a piste of natural snow, an artificial one will last up to five weeks longer when temperatures rise above zero. Second, the structure of artificial snow is uniform. The natural sort settles into packs with wildly different textures. 

This different structure of artificial snow can have a negative impact on the mountain ecosystem.

And why is it sometimes too warm to make snow even when it is below freezing? the article continues:

What matters for snowmaking is the combination of air temperature and humidity, what’s known as “wet-bulb temperature”. Just as human bodies struggle to cool down on humid days, so snowflakes struggle to freeze in moist air. At a wet-bulb temperature of -8℃, which, for example, registers when the air temperature is -5℃ and the humidity a low 20%, it’s easy to make snow. But as the air’s cooling capacity declines, snowmakers have to compensate by pumping less water through the machines. The result is ruinous inefficiency. It takes three times as much energy – and three times longer – to make a cubic metre of snow at a wet-bulb reading of -4℃ as it does at -8℃. At -3℃, you’re using quadruple the energy you needed at -8℃ – though it’s technically possible to make snow, you’d really rather not. Above -2℃, forget about it. The water won’t freeze as it falls to the ground.

Even snow machines do not provide a complete solution for global warming. Human ingenuity is finding increasing numbers of ways to keep skiing viable, but at a cost.

Artificial snow is an environmental disaster. Typically a ski resort will use a billion litres of water in a season to produce artificial snow, with as much as 40% of the water lost through leakage, evaporation or because artificial flakes blow away from the piste they’re supposed to land on. Snowmaking also accounts for approximately 50% of the average American ski resort’s energy costs