Weather at the heart of avalanche forecasting

The avalanche that swept away three snowmobilers at the end of March reminded us of the importance of safety in avalanche terrain. She also highlighted the work of Avalanche Québec and its role in predicting these events.

The Avalanche Quebec team must carefully examine the snowpack to write its bulletins, but it must also scrutinize the weather forecast. It suffered a serious setback in December 2022 when a storm destroyed a weather station at the summit of Mines Madeleine, at an altitude of 1,150 meters, in the Chic-Chocs.

“The weather station was already quite frosty, which made the structure heavier,” says Dominic Boucher, general manager of Avalanche Quebec. There was a peak wind of 180 km/h. And after that, radio silence. When we were able to return to this area a few days later, we discovered the station on the ground, a total loss. There was nothing we could salvage. »

The Avalanche Quebec team had to call on partners, such as the Ministry of Education, the MRC de la Haute-Gaspésie, Nergica, the University of Sherbrooke and SEPAQ, to finance and build a new weather station more robust and better adapted to the extreme conditions of the Mines Madeleine summit. In particular, it has set up a small container which will make life easier for those who come to maintain the station.

“Before, you had to climb into the structure, open the box to the outside,” recalls Mr. Boucher. Sometimes we were with the computer, in the wind, in the snow, trying to do the updates. Now, inside, it’s not hot, we haven’t put any heating on, but at least it cuts the wind. »

To prepare its forecasts, Avalanche Québec relies on three weather stations, two of which belong to it. The third is the property of the Quebec Ministry of the Environment, the Fight against Climate Change, Wildlife and Parks. It is located in the valley, behind the Mont-Albert lodge, at approximately 250 meters above sea level.

One of the Avalanche Québec stations is located approximately mid-mountain, at an altitude of 650 meters, in the Mont Ernest-Laforce sector. The third is the Mines Madeleine station.

“The idea of ​​having distributed them according to the different altitude bands is to know what is happening at critical places in the mountains,” explains Mr. Boucher.

It is also essential to be able to count on stations that can properly capture the snow that falls in the area.

“Where the Summit of Mines station is, even after a storm of 40 to 50 centimeters, there is no snow on the ground, everything is windy,” explains Mr. Boucher. While the Mont Ernest-Laforce station and the Mont-Albert lodge are fairly well protected from the winds, we are able to follow snow accumulations. »

It is very important to measure winds and snow accumulations to evaluate the formation of wind slabs on slopes, the main cause of avalanches in the Chic-Chocs.

“A wind slab is an accumulation of snow carried by the wind which will settle in sheltered areas,” explains Dominic Boucher.

We are thinking in particular of the area located just below the edge of the summit. The accumulation there can be three to five times greater than the amount of snow that falls.

“If we record 10 cm of new snow in the valley, we can have patches of 30 to 50 cm thick, so it is really important for us to follow these patches,” says Mr. Boucher. If this slightly hardened snow has the misfortune of resting on a layer of weaker snow, such as powder or transformed snow, it could be a single skier passing by so that it collapses and triggers the avalanche. »

Fortunately, users, whether skiers, snowshoers or snowmobilers, are increasingly aware of this danger, and avalanche safety training is in high demand.

“It’s a very good sign, we are happy to see the figures from year to year,” emphasizes Dominic Boucher.

He notes that many groups (clubs or friends) now require new members to undergo training and obtain the necessary equipment.

“More and more, what we see is well-equipped people who prepare for their days, who know what they are doing. Of course, there are always people we can’t reach, but now that’s the exception. »