The winter of 1998-1999 will be remembered as 'the avalanche winter'. Four enormous catastrophic avalanches in Chamonix, Evolène, Galtür and Valzur respectively killed 12, 12, 31 and 7 people. A total of 62 people died as a result of the avalanches that raged over and through their homes. Another 5 people died in Switzerland as a result of catastrophic avalanches that winter and the material damage was around 600 million Swiss Francs. A snowy winter turned out to be a catastrophic winter. It's mid-January 2018 and we are again faced with a period of heavy snowfall and extreme avalanche danger. Fortunately, no major disasters have occurred yet. A comparison between then and now.
A catastrophic avalanche is a huge avalanche with devastating force that threatens public life, claims multiple casualties and often occur when the avalanche danger is HIGH or EXTREME. They often arise spontaneously. It's quite a difference with the 'normal' slab avalanche, which in pretty much all of the cases is triggered by a skier or snowboarder. The catastrophic avalanches claimed the most fatalities in the Alps in the past, but due to a set of measures, we're increasingly successful to counter the damage caused by these avalanches. Consider, for example, the temporary closure of roads and railways, the construction of tunnels and avalanche galleries in those places where many avalanches come down, the prohibition to build in those zones of the valley or on the mountain where avalanches regularly come down, and more avalanche protectional measures in the villages, such as preventive blasting of avalanches.
The basis for the avalanche winter of 1999 came in three periods with heavy snowfall from the northwest. It snowed heavily in the Alps between 26-29th of January, 5-10th of February and 17-24th of February. More than 5 meters of snow came down in large parts of the Alps within 5 weeks and the avalanche danger was EXTREME (5 on a scale of 5) frequently. Many roads were closed in that period, complete valleys were shut down and over a hundred thousand tourists couldn't go anywhere.
France was in shock on the 9th of February 1999, when a monster avalanche devastated 14 chalets and killed 12 people. The first snowfall of January 26-29th brought 1 meter of snow to the region, but there was nothing to worry about (yet). The second period of heavy snowfall from February 5th brought at least 2 meters of snow and the avalanche danger rose to EXTREME. The snowfall was accompanied by a lot of wind and that transported the snow to the same faces. Evacuation became a serious subject, but who and why? Construction of new houses was booming in the Chamonix valley and it was easy to understand from a financial perspective. The only problem was that some houses were built very close to known avalanche paths. Evacuation was briefly discussed, but a decision never came and with disastrous consequences. The responsible politician was sentenced to prison for negligence afterwards. Read more about this? Check this article.
Another disastrous avalanche came down in Evolène in the Swiss kanton of Valais on February 21st. During the third precipitation peak that winter the snow climbed so high on the flanks of this village that it had no other option thann to rage down. The avalanche danger in the region was HIGH (4 on a scale of 5) on Saturday, February 20th and again it just kept on snowing. It was relatively warm with the freezing level around 1800-2000 meters.
12 people passed away on the evening of the 21st of February. The combination of powder snow and the heavy snow lower on the mountain formed a gigantic avalanche that left a trail of destruction. Everything that was in the path of the avalanche was dragged down. It formed a pile of snow and debris with a height of 15 meters at the bottom of the valley. The bodies of 12 people were recovered later. Here too, local politicians responsible were prosecuted and convicted. Check out this video to learn more about this devastating avalanche.
The most famous catastrophic avalanche in Austria is the one that came down in the village of Galtür on February 23rd 1999. A huge avalanche rushes into the valley at unprecedented speed from the Grießkogel that afternoon. A huge havoc was the result. As many as 31 people did not survive this avalanche. The avalanche danger in the region was HIGH (4 on a scale of 5) from the 18th of February and the avalanche danger was HIGH to EXTREME (scale 4 and 5 on a scale of 5) from February 20th. The west of Tyrol was hammered by heavy snowfall since the beginning of the month. On average February was very cold and 2 to 3 degrees colder than normal. In addition, a whopping 375 cm of fresh snow came down in Galtür throughout the month (that's six times more than usual). If you look deeper into the data you can see a number of things that stand out.
Especially the high temperature peaks during the second major snowfall and the high temperature peak in the days just before the avalanche are striking. Although it was cold, there were two temperature peaks that certainly had a consequence for the composition of the snow cover. Only a few days after the accident, a massive evacuation was carried out and some 18,000 people were transported out of the Paznauntal. In the meantime, the next catastrophic avalanche came down in the village of Valzur. 7 people lost their lives here. Local politicians were also prosecuted for the avalanches in Galtür, but in contrast to Switzerland and France they were not convicted. Read more? Check this article, p. 132 and beyond
The winter of 2018 started early and it's been snowing in the Alps pretty much every week since the beginning of November. The first really heavy snowfall for the northwest arrives in the second week of December when the avalanche danger rises to HIGH for the first time. The snow cover at that time is 1.5 to 2 times thicker than normal in many places. More snow arrives after Christmas which, at the end of the year, accumulates in a unique storm cycle with sometimes rain up to 2500 meters. The snow cover above 1800 meters grows to enormous proportions and for the first time that winter the avalanche danger rises to EXTREME (5 on a scale of 5) in the northern French Alps. Roads are closed, ski resorts are cut off from the rest of the world and people who were part of the holiday traffic had to spent the night in emergency locations. The third heavy snowfall started on Monday the 16th of January and continued until January the 22nd. Strong winds, shifting temperatures and intense precipitation are the result. The avalanche danger in large parts of Switzerland and the French northern Alps rises to EXTREME on Monday the 22nd of January (5 on a scale of 5). Especially for Switzerland this is a unique situation.
Dozens of roads are closed, several villages are temporarily cut off from the outside world and ski areas are closed. At the same time dozens or even hundreds of avalanches come down. First as loose snow avalanches, but with the rise of the temperature more and more in the form of wet snow or mud avalanches. Fortunately, there are no major accidents. They've done a lot in Wallis to prevent 1999 happening again (Source):
It's still only January and it is not inconceivable that the Alps still have to deal with heavy snowfall the next couple of days. Nevertheless, it is hopeful that Switzerland and the northern French Alps have passed the first major test of mother nature. Catastrophic avalanches can never be entirely ruled out, but the measures taken after 1999 seem to work.