Last week bore the imprint of southerly air currents. At high altitudes, lots of snow was transported. The freshly generated snowdrift accumulations were easily triggered to start with. The unseasonably mild temperatures then improved the situation. The main problems this week were small glide-snow avalanches and moist slides, also distant-from-ridgeline snowdrifts at high altitude and a diffuse old-snow problem on sunny slopes above about 2500 m.
Weather conditions and a brief outlook
The Alps received the brunt of a cold air thrust from the Atlantic in a powerful SW air current. With this, mild and dry air masses were pushed towards Tirol. Subsequently the high-altitude air current shifted to southerly and intensified, which brought about a mighty foehn syndrome.
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| Wide-ranging snow transport on 14.12 in far reaching parts of Tirol. Stubai Alps |
The foehn current will persist until Friday, 20.12, then be replaced by a cold front on Saturday, 21.12. The cold front will terminate the foehn and bring us variable and cooler weather conditions.
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| Striking: very mild temperatures, lots of wind, variable conditions. |
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| Forecast of fresh snow til 21.12. Then additional snowfall will come to Tirol. Temperatures will drop. |
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| Currently, on 19.12: rainfall in southern regions. Snowfall level at 2000 m. |
The snowpack
Last week was taken up by intensive snowpack analysis, also in the context of an avalanche commision course in Galtür. With support from helicopters, also government issue, we were able to concentrate on potential problem zones.
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| En route with the government helicopter. Grosstal (photo: 19.12.2019) |
Upshot: the snowpack is highly irregular over widespread areas, massively affected by winds at high altitudes, generally moist up to at least 2200 m (especially at ground level and on the upper surface). On sunny slopes, we found a series of melt-freeze crusts and faceted crystals, potential weak layers for slab avalanches, especially above 2500 m. Such avalanche prone locations are currently rather diffuse, tend to be of limited distribution.
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| On west-facing slopes we found the worst snow profiles. |
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| Generally in the encrusted zones, no thoroughgoing fractures could be generated. |
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| Highly irregular snow distribution. Heavy wind impact. Silvretta (photo: 18.12.2019) |
The snow quality is poor over widespread areas.
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| En route to the Sulzkogel (17.12.2019) |
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| Indication of a thoroughly wet snowpack (photo. 17.12.2019) |
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| In many places (excluding in southern regions) little-to-no snow at low altitudes. Kitzbüheler Horn (photo: 19.12.2019) |
Release avalanches
This week, there were three avalanches in which persons were involved.
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| Avalanche release in Sulztal. West, appx. 2500 m. One person was swept along, but could escape with injuries. Apparent old-snow problem. |
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| Avalanche just below Lampsenspitze. No one was buried. Material loss. (photo: 15.12.2019) |
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| Below the rocky fundament of the Schneiderspitze in the Axamer Lizum, two ice climbers triggered a slab avalanche. North, 1900 m, very steep. (17.12.2019) |
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| Elsewhere several avalanches were triggered by persons who were not buried by them. Freshly generated snowdrift accumulations atop loose snow layers. Stubai glacier (photo: 13.12.2019) |
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| Especially in NW regions, increased gliding snow activity. Ausserfern (photo: 15.12.2019) |
It is getting more wintery
As mentioned above: it is getting more wintery. To start with, from the south, subsequently from W/NW air currents are being funneled to Tirol which presage precipitation. To start with, most of the precipitation is expected along the Main Alpine Ridge from the Ötztal Alps eastwards, and in the southern part of East Tirol. Then, as the air current shifts, the precipitation will spread, but least of all to the northeastern regions. The old-snow problem referred to above will worsen with this burden of snow. Elsewhere, fresh snowdrift accumulations require increased heed. We also have a latent glide-snow problem
