Lots of snow + wind. And now, a high-pressure front
Following days with ample snowfall and storm-strength winds, beautiful weather is on the way.
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A turbulent week lies behind us. Windy, initially warm with rainfall, snow depths reducing slightly thereby, followed by a cold front, with lots of snowfall in places. High-pressure front starting on 6 February. |
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| In parts of Tirol, up to 100 cm of fresh snow was registered over the last 3 days. |
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| One of the snowfall hot spots: Karwendel Massif. In photo, Seegrube above Innsbruck. (photo: 05.02.2020) |
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| It was also rather stormy. |
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| And not only in the mountains. East Tirol (photo: 05.02.2020) |
Main danger currently: fresh snowdrifts
The avalanche situation for backcountry winter sports enthusiasts is treacherous above the timberline for a brief spell. Fresh drifts are the main danger. Fresh snowdrifts constitute the main danger. This is confirmed by avalanche releases in which skiers/freeriders were involved today (6 February). Fortunately, the avalanches caused no grave injuries.
Avalanches during the last few days
Due to numerous reports we now have a good overview of avalanche releases of the last few days. We extend a huge THANK YOU for these reports. It is clear that most avalanches were released in the fresh snow. A few of them fractured in the expansively metamorphosed (faceted) layers which occupied us before the rainfall of 3 February. The latter situation was observed only in isolated cases, and then, above 2300 m (in other words, above the rainfall level).
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| Avalanches in Northern Massif. (photo: 06.02.2020) |
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| Slab fracture in Bockkar. Ausserfern. (photo: 06.02.2020) |
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| Explosions with varying success throughout the land. Most were in the Stubai Alps. (photo: 06.02.2020) |
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| Most avalanches were observed adjacent to ridgelines, i.e. on sunny slopes. Stubai Glacier. (photo: 06.02.2020) |
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| Ridgeline slab, east-facing slope, Roter Kogel, East Tirolen Main Ridge. (photo: 06.02.2020) |
Winter sports enthusiasts were involved in avalanche releases on the Arlberg, in the Silvretta and in the Ötztal.
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| A skier wanted to enter the slope behind the closure and was able to stand still as the avalanche released. Ski area Sölden. (photo: 06.02.2020) |
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| One of the few avalanches we know of which fractured in the old snow. Gleirschtal. (photo: 06.02.2020) |
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| A look back. Naturally triggered avalanche due to expansively metamorphosed weak layer and warmth. Eastern aspect, about 2300 m, 31 January. The following days released additional such avalanches due to massive warmth and rainfall. (photo: 01.02.2020) |
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| Loosely-packed avalanches in extremely steep terrain due to solar radiation. Mieming Massif. (photo: 06.02.2020) |
A look inside the snowpack
Recent snowfall was marked by layers of graupel. This may well have formed a weak layer for slab avalanches. A further weak layer was formed by the fresh snow blanketing everything. Both are prone to triggering for a short time. Caution urged mostly towards sunny terrain and, in the heights, shady slopes.
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| Throughout the land wherever snowfall was heavy: graupel. Ausserfern. (photo: 04.02.2020) |
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| Indicative of the current snowpack layering. There are several weak layers inside the masses of fresh snow. Northern Massif. (photo: 06.02.2020) |
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| Weak layers near the surface. The lower layer shows a melt-freeze crust, beneath that is a faceted layer of snow crystals. Where the snowpack can be disturbed, esp. above 2300 m in W/E aspects, there is barely tracked terrain. Ötztal Alps. (photo: 02.02.2020) |
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| Avalanche warners from EUREGIO during their snowpack analysis in the Lienz Dolomites. (photo: 06.02.2020) |
Danger pattern cold-on-warm (dp.4) could become a threat!
We are currently observing with particular attentiveness a borderline layer between the thoroughly wet old snowpack surface generated by rainfall and the fresh fallen snow. Due to huge temperature differences, a weak layer might well form over the coming few days. As yet we have not been able to find anything of concern in the borderline regions of these layers. As soon as we have concrete evidence, we will publish it.
A request to all winter sports enthusiasts who occasionally like to have a look into the snowpack: we are grateful for all your reports about snow transformation (i.e. Are there faceted crystals? What do the stability tests show?) The best thing is to report it directly to lawine@tirol.gv.at THANK YOU.
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| In the picture, old snowpack and fresh snow deposited on top of it. In the borderline regions between moistened / thoroughly wet old snow and cold fresh snow (see arrows) the faceted crystals about to form can be seen. (photo: 05.02.2020) |
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| Snow profile shows striking temperature disparities at the borderline between old and new snow. |
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| Exactly the same situation as in the profile above. |
What’s next?
...that is precisely what the EUREGIO avalanche warners think about every single day...
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| The EUREGIO avalanche warners Lukas (South Tirol), Norbet (North Tirol) and Sergio and Gianluca (Trentino) at their analysis of the current situation and joint compositon of an avalanche bulletin. Dolomite Hut. (photo: 06.02.2020) |
The coming days will be dominated by beautiful weather. Fresh snowdrifts need to be cautiously assessed at high altitude. For that reason, we advise backcountry skiers/freeriders towards caution. Most critical currently: ridgeline terrain at high altitudes where there are many snowdrift accumulations. Also at 2300-2800 on west and east-facing slopes, in transition zones from shallow to deeper snow where snowfall has been heavy, large-sized avalanches could trigger.
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| Incidentally, powder can also still be enjoyed in a few places. Wankspitz, Mieming Massif. (photo: 05.02.2020) |
As already mentioned, a new weak layer could form (based on dp.4) which might prove a threat in the rain-impacted regions, especially above the timberline.
