After an extended period of beautiful weather, the big change has arrived. It will bring noticeable precipitation after a long dry spell. Fresh snow and winds will swiftly lead to a striking increase in avalanche danger. In the regions where snowfall is heaviest, avalanche level 4 (high) will be reached. Backcountry skiers and freeriders are particularly at risk. Exposed transportation routes will not be endangered, or only in isolated cases.
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| On the Vorarlberg border and in northern barrier cloud regions, 50-70 cm of fresh snow is expected by Wednesday, 29.1.20. | | | | |
Weather
After a long period of fine weather, interrupted briefly by a weak perturbance on 18-19 January, a major weather change is coming, bringing notable amounts of precipitation. Today, 28.1, a cold front will pass through from the west, bringing fresh snow. The snowfall will be accompanied by strong to storm-strength and gusty northwesterly winds. Gusts of 80 km/hr are anticipated over widespread areas, in the Allgäu Alps-Karwendel region up to 100 km/hr. This cold front is the vanguard of a weather phase bringing variable, instable conditions, typical of a western airstream. It will remain highly variable even after the precipitation is over.
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| In the Allgäu Alps as far as the Karwendel, gusts of over 100 km/hr are expected. | | | |
Snowpack
The fresh snow will be deposited on top of an expansively metamorphosed snowpack which formed during the period of fine weather, including many nights of outgoing radiation. Once it is blanketed by bonded snow, this surface of faceted crystals will be an unfavourable snow base. On shady and wind-protected slopes, surface hoar has also been frequently observed. The loosely-packed old snowpack plus the fresh fallen snow are perfect ingredients for a highly accident-prone danger pattern, namely,
dp.5 (snowfall after long period of cold.
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| An expansively metamorphosed snowpack all the way down to the ground is visible here in the Axamer Lizum, and is widespread throughout Tirol. | . | | | | | |
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| Hard tracking in northern Stubai Alps because the snowpack is loose all the way down to the ground. | | |
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| Loosely-packed, expansively metamorphosed snowpack surface in central East Tirol |
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| On shady and wind-protected slopes, surface hoar is frequently observed. |
The fresh snowdrifts can be easily triggered, even with minimal additional loading. Moreover, in regions where snowfall is heavy increasingly frequent naturally triggered avalanches can be expected. Avalanche danger will reach at least level 3 - considerable; and in the regions where snowfall is heavy, level 4 - high. The avalanche danger level refers mainly to winter sports enthusiasts, often nicknamed “Skier High” to connote that few very large avalanches can be expected but very many medium-to-large avalanches can trigger naturally. In addition, avalanches can be easily triggered even by minimum additional loading in many places. In such a “Skier High” phase, all backcountry skiers and freeriders are in acute danger. Exposed transportation routes are at risk only in isolated cases.
Skiing and freeriding tours in outlying terrain demand a lot of experience in danger assessment on-site, as well as a great deal of restraint (
New snow problem).
