The avalanche situation is currently very treacherous, particularly in North Tirol and in northern regions of East Tirol. The threat stems from wide-ranging snowdrift accumulations which are found in all aspects at and above the timberline, especially in gullies, bowls and behind protruberances in open terrain. It is still quite cold in the mountains, the snowdrifts thus remain prone to triggering and are easily dislodged by even the weight of one sole backcountry skier. Since the wind has incrementally slackened off since yesterday evening (09.01) the snowdrift accumulations are frequently covered, making them difficult to recognize.
Friday (11.01) promises to be sunnier, for the first time in a while in North Tirol. In combination with the above-described snowpack layering, a thoroughly risky and accident-prone day awaits us. We advise all backcountry skiers and freeriders to be utterly defensive in their conduct in outlying terrain. The inexperienced should not leave the secured and marked ski runs.
Ongoingly, as a result of the forecast solar radiation, naturally triggered avalanches can be expected in isolated cases tomorrow, particularly on SW to S to SE facing slopes. These releases can attain large-to-very-large size in the main areas of precipitation along the Bavarian border (avalanche sizes).
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| The snowpack remains prone to triggering (Northern Massif) (photo: 09.01.2019) |
All the way down to the valley floor, the snow cover is far deeper than usual for this juncture of the season. Glide-snow avalanches on steep, grass-covered slopes can grow to impressively large size and become a danger not only to skiers and freeriders, but also put transportation routes and buildings at risk. The problematic factor is this: glide-snow avalanches are utterly unpredictable, can release over the ground at any time of day or night. For that reason, zones below glide cracks in the snowpack surface should be avoided.
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| High risk of danger from glide-snow avalanches prevails widespread in Tirol, as here in the Tux Alps. Contrary to widely held opinion, a glide crack is not a sign of improving conditions, but quite the contrary, in most cases is an indicator of imminent danger of a glide-snow avalanche. (photo: 08.01.2019) |
Apart from trigger-sensitive snowdrift accumulations, in East Tirol south of the Main Alpine Ridge and north of the Drau, it is still possible for avalanches to trigger in the old snow. The most threatening potential layer is one of faceted crystals which formed around the melt-freeze crust on 6 December (GM4). Avalanche prone locations are found in all aspects between about 2200 and 2700 m and in general in very steep terrain. This weak layer can generally be triggered only by large additional loading. In places where the snow is shallow, however, there are also possible “hotspots” where even minimum additional loading can trigger an avalanche.
The immense amount of snow threatens more than the obvious danger of avalanches. Accidents in Salzburg and in Switzerland demonstrated just how fast a skiing accident in meter-deep, unbonded fresh snow can end in tragedy. It can sometimes be quite difficult to free oneself after a fall in deep snow. If your head is buried in snow, the risk of suffocation makes it more difficult still. What counts here is keeping your skiing partners in immediate view in order to react as quickly as possible when necessary. As in avalanches, the person buried usually has only a few minutes of survival. If such a person is not immediately found, the avalanche sensor device can help to pinpoint the victim.
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| Slope closures must be heeded without question. photo: 10.01.2019) |
Review
Several days with reams of fresh snow and storm-strength winds are behind us. Since the launch of this period of snowfall on Tuesday morning (07.01) there has been a great deal of fresh snow registered in far reaching areas of Tirol. Most of it fell in the northern barrier-cloud regions, from the Lechtal and Allgäu Alps over the Karwendel to the Wilder Kaiser. As so often to date this winter, the precipitation was accompanied by storm-strength winds in many places.
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| Amounts of settled fresh snow between Monday, 07.01 and Thursday, 10.01. |
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| Storm-strength northwesterly winds. |
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| Stormy: Stubai Glacier (photo: 07.01.2019) |
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| Interesting effects of extreme snow depths: the temperature sensor on the Seegrube has been buried in snow since 05.01. Apparently it lies 108 cm beneath the snowpack surface. |
Snowfall was most intensive on Tuesday night and the early hours of 09.01. During this time window the apogee of naturally triggered avalanche activity was also reached. The loosely-packed fresh snow was swept into the plummet paths of slab avalanches so that truly imposing powder-cloud avalanches developed in extremely steep terrain.
Every single one of the avalanches we are aware of and which poured over roads were either glide-snow or loosely-bonded snow avalanches. Tomorrow, Friday, when visibility improves, we can obtain a more comprehensive overview of the situation.
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| A glide-snow avalanche displaced a community road in the Astegg district of Finkenberg. (photo: 07.01.2019) |
On Wednesday, 09.01, there was an avalanche accident in Zammermoos, below the Galzig in the outlying terrain of the St. Anton am Arlberg skiing region. A 16-year old Australian lost his life. The avalanche was about 140 m long, about 45 m wide on average and triggered on a 45° gradient slope. The fracture depth of the avalanche varied from about 20 cm to 100 cm (For details go to LAWIS). The weak layer was a very thin layer of faceted and decomposed snow crystals which had formed only recently as a result of the temperature disparities during the snowfall (danger pattern: cold on warm). In addition, there was also graupel found in the uppermost layers of the snowpack, although not so prevalent as to be the primary weak layer.
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| Avalanche release Zammermoos on 09.01.2019. The place of burial is marked. (photo: 10.01.2019) |
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| At the Ulmerhütte weather station in the vicinity of the accident spot the temperature fluctuations of the last week are visible, a requirement for the danger pattern Cold-on-Warm. |
While North Tirol was immersed in snow, southern regions were at a loss. Precipitation reached the Dolomites, but the amounts were extremely modest. (Connyalm: 7cm; Porzehütte: 2cm).
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| Very little precipitation: observers in Obertilliach are still waiting for the very first snowfall of the winter. |
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| Great precipitation: in the last 7 days on Pillersee in the Waidring Alps, about 140 mm of precipitation was measured. |
Outlook
A temporary improvement in weather is anticipated on Friday 11.01, as mentioned above. Winds will be light to moderate from the north, somewhat stronger on the Main Alpine Ridge and in East Tirol north of the Drau. Due to the low temperatures, no significant improvement in the avalanche situation is expected. On Saturday, as a result of light snowfall and intensifying winds, the next front will make its entrance. From today’s perspective, things will turn serious again on Sunday and on Monday. We expect heavy snowfall once again, which will bring us immense amounts of fresh snow in the Arlberg region and on the Main Alpine Ridge more than anywhere else.
An update will be published in the next few days...
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| The snowpack will grow further at the beginning of next week. Northern Massif. (photo: 10.01.2019) |
