Numerous naturally triggered avalanches
We have just completed a phase of numerous naturally triggered avalanches. Some were very large and swept over exposed transportation routes, primarily in the western regions where snowfall was heaviest. Due to higher temperatures and rain impact, glide-snow avalanches have also increased. Particularly in East Tirol where snowfall has been heavy, some large-sized releases provide ample evidence.
Naturally triggered avalanche activity has receded significantly. Today (30.01) isolated releases in western regions were reported. The reason seems to have been additional snowpack loading due to heavy snow transport. Starting tomorrow (31.01) thewinds should be far lighter. Impulses for naturally triggered avalanches could then come from diffuse radiation effects (near cloudbanks) although that is still hard to predict.
Situation for wintersports enthusiasts remains treacherous regionally
What remains is a regionally delicate situation for wintersports enthusiasts. This applies primarily to zones above the treeline. Below that altitude, due to rain and warmth, most of the weak layers inside the snowpack have either been activated already, or have dissolved. At low and intermediate altitudes the danger of glide-snow or (in extremely steep, rain-impacted terrain) wet loose-snow avalanches remains.
Above the timberline, on the other hand, wide-ranging snowdrift masses have been generated by snowfall and wind. These constitute the perfect “slab” and can be easily triggered by wintersports enthusiasts, particularly in transitions from shallow to deep snow. In isolated cases, even remote triggerings have been reported over the last few days – something characteristic of large-spread weak layers, mostly at mid-level in the snowpack. Since avalanches can fracture down to more deeply embedded layers of the snow cover, they can then grow to dangerous size for wintersports enthusiasts.
Several recent avalanches involved persons, two with fatal results
Since mid-January we have experienced a period in which increasingly frequent avalanches have involved persons and this period seems to be continuing. Headquarters today received seven reports of such avalanches, plus one of a cornice breaking (Zwölferkogel) and a rooftop avalanche in Lienz. The releases in East Tirol were on Hollbrucker Spitze on the Carnic Ridge and on Figerhorn in the Glockner Massif. The other avalanches were all in the Stubai Alps, increasingly in the Sellraintal: Schafzöllen, Vorderer Grieskogel, Neunerkogel, Widdersbergsattel and Zubusserkopf near Trins).
What we already know about the fatal avalanche accidents
Avalanche Neunerkogel (northern Stubai Alps)
The slab avalanche triggered when a person was in the 40° steep north-facing descent at approximately 2150 m altitude. The avalanche was about 150 m long and 80 m wide. The person did not have a transceiver, was found by an avalanche dog, buried about 50 cm beneath the surface. Resuscitation attempts were in vain.
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| Screenshot from www.lawis.at: the accident spot is visible below Finstertal Reservoir in the Kühtai. Near the avalanche, our observer Lukas Ruetz made a snow profile after the accident. At right, the results of this profile: the avalanche triggered in the wide-ranging weak layer in the middle of the snowpack. |
Avalanche Widdersbergersattel (northern Stubai Alps)
According to information of the rescue team leader (Mountain Rescue Axams) one sole tourer was in the ascent up the Widdersberg, departing from Axamer Lizum, and was buried by a slab avalanche beneath nearly 2 metres of snow. The avalanche was about 100 m wide, triggered right beneath the Widdersberger Sattel at about 2260 m altitude. The slope faced E-SE. Two persons saw the avalanche and the ski tracks leading into it, were able to immediately find the spot where he was buried. After about 40 minutes, the C1 crew was on-site, engaged in resuscitation attempts, which did not succeed. We assume, due to the similarity of terrain and snowpack analysis, that the problem causing the avalanche was the same as on the Neunerkogel.
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| Approximate site of avalanche beneath the Widdersbergersattel. (c) tiris |
A footnote (20 min following publication):
We just received notice that someone who was involved in the search-and-rescue operation after the avalanche beneath Vorderer Grieskogel, Kühtai, requested that we publish the following: the avalanche path was in the immediate vicinity of the Kaiserjochbahn. Persons who were on the lift and had their beacon devices turned on influenced the search enormously. Possibly there is a lesson to be learned: that lift personnel should ask people to turn off their beacons in the lift.
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| Avalanche Vorderer Grieskogel. Search-and-rescue team and Kaiserjochbahn (photo: (c) Gerold Santer on 30.01.2021) |
