Avalanche releases, fractures, settling noises: clear signals of alarm. Fresh snowdrifts in steep terrain need to be circumvented.
Our prior assessment of a delicate situation regionally for winter sports enthusiasts was confirmed today, 29.12. We received repeated reports of mostly medium-sized, in isolated cases also large-sized naturally triggered avalanches. In addition, slab avalanches were triggered by persons. So far, no injuries.
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| Naturally triggered slab avalanche in Tux Alps (photo: 29.12.2020). On the windblown ridge, wind impact is amply evident. |
This applies to southern parts of the land with more snowfall since yesterday (28.12), often 20-40 cm, from place to place as much as 60 cm of fresh snow, amid strong wind influence.
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| Precipitation 28-29 December. East Tirol got the brunt. |
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| Snow, snow, snow - Lienz basin (photo: 29.12.2020) |
Fresh snowdrifts react extremely sensitively to additional loading. They are deposited on top of the following weak layers:
- Diamond snow (especially loosely-packed ‘champagne powder’) and loose powder in all aspects
- Surface hoar, esp. at forest rims in all aspects, regionally also further up on north-facing slopes
- Faceted crystals near melt-freeze crusts formed on 22 December (heightened trigger sensitivity on north-facing slopes at 2100-2300 m, in E-S-W aspects at 2200-2500 m.
Information received today about numerous fracture cracks and settling noises at forest rims and above.
We currently rank avalanche danger as HIGH (level 4), due to high proneness to snowpack triggering in southern East Tirol above timberline.
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| Danger level map for 30.12.2020 |
This is a so-called “Winter Sports Enthusiasts HIGH” - in other words, a situation in which likelihood of slab avalanches triggering above the timberline by additional loading on the snowpack is ranked as HIGH. In addition, avalanche prone locations are widespread, they occur in all aspects. This was the reason why our observer in southern East Tirol was able to carry out his explorations only in moderately steep terrain up to the treeline. Above that altitude, particularly due to limited visibility, it was too risky to tread the snowpack. On the borders of the “high danger” region, the risks above forest rims are also extremely high. Lots of experience is required, along with great restraint.
In conclusion, our repeated appeal to one and all: recently generated snowdrift accumulations in steep terrain should under all circumstances be CIRCUMVENTED.
