Favourable avalanche situation widespread. Snow quality is deteriorating.

Weather Overview

High-pressure conditions predominate

Last week enjoyed the impact of a stable high-pressure front with only brief interruptions. Temperatures were above average for this juncture of the season. Little change in this scenario is anticipated over the next few days. A weak cold front on 10.01 will bring some precipitation in the evening as temperatures drop slightly. Thereafter, sunshine will continue. Light winds, mild air in the mountains. In the valleys, a temperature inversion is expected.

Beautiful weather in general this last week. Pirchkogel in northern Stubai Alps (photo: 05.01.2020) 

Typical weather development of the last week: only brief disturbances. Mostly beautiful weather. Windy in the mountains. Far too warm for this juncture of the season. Nachtweide station in Silvretta Skiarena 

Some precipitation

...was registered between 04.01. and 05.01.2020.

Most of the precipitation fell in eastern regions, as here in the Wilder Kaiser region.

The major bouts of precipitation of the last week.

Fresh snow on Stubai Glacier (photo: 05.01.2020)

Windy on Main Alpine Ridge in particular

Typical wind distribution last week. Winds were strongest in the regions along the Main Alpine Ridge.

Snow plumes along Main Alpine Ridge in Gurgl group (photo: 05.01.2020) 

Storm winds in Obernbergtal (photo: 05.01.2020)

Favourable avalanche situation

The avalanche situation corresponds to the weather: avalanche danger levels have continually decreased after a brief regional rise to ‘considerable’ above the treeline on 4/5 January. In the European Region Tirol-South Tirol-Trentino low danger currently prevails in general.

A uniformly favourable picture of the avalanche situation in the European Region for 10 January 2020.

Main danger: isolated glide-snow avalanches

There are currently very few avalanche prone locations. Caution is nonetheless urged towards isolated glide-snow avalanches on steep, grass-covered slopes, generally of medium size.

Glide cracks yawn wide in some places. In isolated cases also avalanches, particularly in precisely those spots. Thus, the rule of thumb is: avoid stopping below glide cracks. (photo: 07.01.2020)

Caution: glide-snow avalanches can plummet for long distances. This avalanche triggered on a W/SW slope at 2250 m in rear Gschnitztal. (photo: 02.01.2020)

Backcountry descents: on very steep slopes

That, too, corresponds to the current situation. Backcountry enthusiasts are skiing and boarding down very steep slopes. Avalanche releases are not the problem there, but rather a fall. This applies ‘only’ to very steep terrain where wind crusts are often hardened.

Backcountry in the Lienz Dolomites (photo: 06.01.2020)

Snowpack Overview

Generally poor snow quality

The deteriorating snow quality is striking. Generally the snowpack has been massively affected by winds or else thin melt-freeze crusts have formed on the surface. In zones where neither sunshine nor wind have done their work, one often breaks through down to the ground, particularly on shady slopes in regions of Tirol where there has not been much snowfall. In a nutshell: if you are in outlying terrain, it is only fun if you are a very good skier/boarder.

The work of the wind in Stubaital (photo: 05.01.2020)

Shining surface (from melting process) adjacent to wind-affected surface  (photo: 05.01.2020)

Typical snowpack layering

Snowpack without weak layers in the Kitzbühel Alps

Wind-affected snowpack surface, below that an expansively metamorphosed (faceted) layer from a long period of fine weather and high nocturnal outgoing radiation. Melt-freeze crusts stem from the warm weather in December including rainfall in mid-November and on Christmas Eve. In the interim, the snowdrifts have bonded well with the faceted layer, partly due to moister air masses on 3/4 January which moistened the uppermost layers in places.

Several melt-freeze crusts, well bonded with each other, in steep-sunny terrain

As mentioned above, beneath hardened wind crusts in wind-exposed, shallow-snow zones there are often loosely-packed, expansively metamorphosed (faceted) layers. Only seldom are the crystals in those areas absolutely unbonded over larger expanses, more often they’re encrusted.

Expectations for the coming few days

The favourable avalanche situation will persist. Caution urged in very steep terrain where the risks of taking a fall currently outweigh those of being caught in an avalanche. Keep glide cracks in view, that is where the greatest avalanche dangers currently stem from. In shallow-snow, wind-exposed, very steep zones, large additional loading could initiate a fracture in quite isolated cases and subsequently unleash a (generally small-sized) slab avalanche.

Snowfall + wind: rising avalanche danger

Following a week of high-pressure weather conditions and generally quite favourable conditions, winter sports enthusiasts have to realign their sights: starting on 4 January wind and snowfall will swiftly lead to heightened avalanche danger. Freshly generated snowdrifts on W/N/E facing slopes, particularly in wind-protected zones, will be easily triggered by backcountry skiers and freeriders.

The weather this last week

Mostly high-pressure conditions

During the last week, i.e. as we crossed over into the new year, a high-pressure front dominated. From the northwest, very mild and dry air masses flowed over the Alps. At ground level, cold air formed layers leading to huge temperature disparities between mountain peaks and valley floors (temperature inversion).

Generally fabulous weather for winter sports. En route in Virgental (photo: 31.12.2019)

On 27.12, moist air masses lodged against the Alpine flanks. Thereafter, very dry and mild air masses flowed in. At high altitudes it was often quite windy. Station Gallreideschrofen in Gschnitztal.

A similar picture in East Tirol Particularly on 28.12, strong winds were blowing in the heights.

Quite windy at high altitudes

This last week was subjected to repeated bouts of heavy wind impact, particularly in the southern regions at high altitudes. On 02.01, winds at high altitudes will again intensify, especially in the classic foehn-influenced zones and on the Main Alpine Ridge. On 03.01 the high-pressure conditions will diminish in force, the airstream will shift from southerly to westerly and the air will slowly gain in moisture.

Heavy wind impact (photo: 28.12.2019)

A typical picture on 28.12 in East Tirol: huge snow plumes on the mountaintops.

View from Tux Alps towards Main Alpine Ridge, where snow plumes are visible. (photo: 28.12.2019)

Snowpack development

Wind-impacted snowpack surfaces, esp. at high altitudes

Due to wind influence the snowpack surface is highly irregular, at least at high altitudes. In addition, shallow-snow spots alternate with deep-snow spots. Ridgeline zones were often utterly windblown.

Erratic snowpack surfaces in northern East Tirol (photo: 29.12.2019)

Huge wind swirls above Nauders (photo: 29-12-2019)

Thoroughly wet snowpack, esp. on sunny slopes

The warm temperatures and solar radiation made the uppermost layers of the snowpack (at very least) moist on E-S-W facing slopes in particular. This, in turn, weakened the snow. In extremely steep terrain, increasingly frequent moist loose-snow avalanches were observed for that reason.

Conditions like in springtime on sunny slopes. Central Lechtal Alps (photo: 01.01.2020)

Expansively metamorphosed snow in cold-air zones and in shady terrain

During star-studded nights, the snowpack cooled down massively. This reinforced the formation of loose crystals near the snowpack surface. It often resulted in decomposed snow or faceted crystals, in some places also surface hoar.

Surface hoar at 1200 m in the Mieming Massif (photo: 29.12.2019) 

On New Year’s Day, many valleys east of Innsbruck were swathed in fog. At the upper borderline of the fog, surface hoar often formed, but persisted only on shady slopes.

So-called burled powder is pictured above. Terrific for skiing, but already somewhat metamorphosed. This requires caution in case of approaching snowfall. En route in Sellrain, Fotscher Windegg. (photo: 29.12.2019)

A loosely-packed snow cover in which skiers break through the snow down to the ground. Poor snowpack structuring for approaching snowfall. This is a wind-protected shady slope at 2090 m.

Frequently good snow quality

Great powder in the northern Stubai Alps (photo: 01.01.2020)

 Dream-come-true descent in Lechtal Alps (photo: 29.12.2020)

Snowpack analysis

During our snowpack analysis we concentrated not only on the snowpack structuring of the surface layers, but also on the processes unfolding inside the snowpack near to the upper surface, specifically, on the generation of potential weak layers corresponding to Danger Pattern 4 (cold on warm), both from 21.12 and from 24.12. On those dates, moister and relatively warmer layers were covered by new fallen snow. Our conclusion to date: from region to region, faceted crystals have formed at the borderline to the layers which might constitute weak layers for the snowdrift accumulations deposited on top of them, but only in rare cases. Most suspicious in this respect is a narrow altitude band between 2100 and 2300 m on shady, very steep slopes.

The arrow points to a moist layer from 24.12.

Immediate vicinity of prior snow profile site: a melt-freeze crust developed from a moist layer. Bordering on that, no formation of faceted crystals.

South-facing slope at 2000 m, a thin weak layer expanded inside a warm layer on 24.12. Warmth had a favourable effect.

As the avalanche accident on the Gamskarspitze on 31.12.2019 demonstrated, there are loosely-packed layers beneath the wind crusts in zones where snow is shallow. These are isolated avalanche prone locations which occur particularly in high altitude zones.

The arrow points to a potential weak layer for slab avalanches below a hardened, wind-impacted layer. Large additional loading would be necessary to trigger this layer.

In isolated cases, there are faceted crystals beneath old melt-freeze crusts which can be triggered. W/E facing slopes above about 2500 m, S-facing slopes above 2800 m. This is a rain crust on shady slopes, formed in mid-November, in an altitude band between 2100-2400 m. Triggering seems likely only by large additional loading.

Fracture of faceted crystals beneath a melt-freeze crust, on shady slope at 2300 m in the southern Ötztal Alps (photo: 01.01.2020) 

Avalanche events

Over the last week, there were many winter sports enthusiasts in the mountains. In proportion to these numbers there were relatively few who triggered avalanches, a sign that the snowpack is well structured. An overview can be found here: one avalanche ended with a fatality on the Gamskarspitze in the western Verwall Massif. See previous blog.

Avalanche Scheibenspitze in Navistal (photo: 31.12.2019). The prerequisites seem to have been the same as for the avalanche accident on Gamskarspitze: shallow snow, wind-impacted, extremely steep, shady, 2400 m.

Avalanche Kesselspitze. Snowdrift accumulation triggered when a skier sprang into it on the slope. Arrow: ski tracks of two skiers who skied out of the avalanche path. Circle: two other persons on their descent. (photo: 29.12.2019)

Avalanche in Huilahner Kogel on 29.12, southern East Tirol (photo: 31.12.2019)

Increased glide-snow avalanche activity

The snowpack was already quite moist before 21.12, then was made thoroughly wet by the warm temperatures on sunny slopes. This reinforced gliding snow masses over steep, grass-covered slopes. Glide-snow avalanches were observed in North Tirol and in East Tirol.

Hot spots of glide-snow avalanches were in the Arlberg and Ausserfern regions, as well as the Tux Alps.  (photo: Arlberg region on 01.01.2020

Glide-snow avalanche near Berwang in the Ausserfern region (photo: 29.12.2019)

A serious danger to be considered on all backcountry tours, Ausserfern.  (photo: 28.12.2019)

Glide-snow avalanches sometimes grew to large size. Tux Alps (photo: 31.12.2019)

What’s next?


As referred to above, avalanche danger is expected to swiftly increase, and steadily in wind-influenced regions. This applies particularly to terrain where the snowpack is currently composed of loosely-packed crystals, and it especially includes shady terrain.

When on 4 January two front systems collide on the northern flank of the Alps in swift succession and new fallen snow is the result, also lower altitudes will be influenced by this event wherever precipitation is heavy. And in particular, wherever fresh snow is deposited on top of surface hoar.

Bildunterschrift hinzufügen

The danger will rise to considerable. Winter sports enthusiasts need to adjust to the new situation and the changed conditions - and consequently circumvent the freshly-generated snowdrift accumulations in steep terrain. For all untertakings in outlying terrain, great experience in assessing avalanche dangers on-site is essential.

Appendix: on 02.01 at 5:17 pm, Tirol headquarters reported an avalanche below the Nuremberger Refuge in the Stubai Alps. It is assumed that some persons were buried in snow. Strong-velocity winds are currently blowing on-site.

Avalanche accident Gamskarspitze, Western Verwall Massif, 31.12.19

On 31.12.2019, Tirol headquarters reported an avalanche below the Gamskarspitze in the western Verwall Massif just after 1:30 pm. One person was caught by the avalanche, was swept along several hundred metres and completely buried. The person died on the scene of the accident.

On 01.01 we were on-site with the state helicopter together with Alpine police in order to examine the evidence. It was a slab avalanche, the upper zone of the release was at 2450 m altitude, on an extremely steep north-facing slope. The avalanche triggered when one person was descending on skis near the fracture break.

Avalanche Gamskarspitze on 31.12.2019: the arrow points to the entry track, the ellipse marks the spot of burial. The accident site is located south of the toll station of the Arlberg divided highway S16. (photo: 01.01.2020)

Magenta marking: avalanche starting zone of the accident on the Gamskarspitze. The arrow points to the entry track. Blue marking in the background: an additional avalanche can be seen. This triggered naturally on 25.12 towards the end of a period of heavy precipitation. (photo: 01.01.2020)

The slope in the starting zone is 40 degrees steep. The steepest spot is about 20 metres below the fracture, where the gradient is 43 degrees. Our snowpack analysis showed that the snowpack in the upper avalanche zone was massively wind-impacted. Inside the snowpack, hardened wind crusts dominated. Below these, we found layers of faceted crystals. What was striking: the snow in this zone was shallow.

Upper (steepest) part of starting zone. (photo: 01.01.2020) 

Snow profile, recorded orographically, left of the entry tracks at the avalanche fracture. Decisive for the avalanche were the faceted crystals beneath the wind crusts.

This profile was recorded orographically right, a few metres above the fracture. Also here, wind crusts are visible, and beneath them, faceted crystals. Fractures artificially triggered by us did not break through the entire block.

The layers which were separated were wind crusts. Beneath those, the snow was softer. This photo corresponds to the snow profile above. (photo: 01.01.2020)

130 metres below the fracture point, orographically right of the avalanche deposit, a similar picture. Shallow snow on a wind-exposed site. Wind crusts, beneath them faceted crystals. No complete break upon additional loading.

The depth of the fracture varies from just a few centimetres to 190 cm (marking in background). The slope was skied in the foreground. (photo: 01.01.2020)

Spot of burial in a narrow trench. (photo: 01.01.2020)

What was significant for this avalanche was: Danger Pattern 7 (shallow snow next to deep snow). In wind-exposed zones where the snow is shallow, layers of expansively metamorphosed (faceted) snow crystals tended to form beneath the wind crusts from place to place to an increased extent.