SnowFlurry 2 2021/22 | Snow profile review

Read the snow profile

General information

The snow profile was recorded on the second of December at 2:30 pm in Sölden between the Gaislachkogel and the toll station to the Rettenbachferner at 2350m. We are here on a 29° steep northeast slope. During the recording, the air temperature is -9.8°C, the snow surface temperature -8.5°C. There is no wind and it is very cloudy while it is snowing lightly.

In the comments field, we read about subsidence noises that the snow profiler Tobias heard here. The test result also matches this: ECTP9 in a prominent weak layer.

All layers are dry. This can be recognized by the number "1" in the column with the crossed-out circle. The moisture levels go up to 5, where 2 stands for "slightly moist" and 5 for "waterlogged".

The temperature gradient from the surface to the first measuring point within the snow cover ten centimetres below is very pronounced: from -8.5°C to -5.5°C. Below this, further temperature measurements were taken approximately every ten centimeters, showing a somewhat steeper gradient. Near the ground, the temperature is close to 0°C.

Blue

About 85 cm of snow lie at the site, divided into seven layers, which were determined using a hand profile. The top layer contains fresh new snow with a grain size of up to 2mm and a hardness of 1 (= fist). This means that the blue bar only extends to the first line on the graph to the left and you can easily penetrate the layer with your fist without exerting much force.

Below this, we see two layers with crystals that have already been more strongly degraded or drift snow. These consist primarily of round-grained crystals with a size of 0.5mm and a hardness of up to 2-3. This means that the layer is very difficult to penetrate for hardness grade 2 (four fingers) and very easy for hardness grade 3 (one finger).

Red

Between a height of 50cm and 35cm, there is a striking weak layer with hardness grade 1. It consists of angular crystals with a grain size of 1.5 to 2mm. The stability test is broken in this layer, in this case an Extended Column Test ECT with the result ECTP9. This means that on the ninth impact during the first wrist loading stage, the entire block with a width of 90 cm and a depth of 30 cm - which had previously been cut out of the snow cover at the sides and rear - broke apart into an upper half and a lower half. This was in the weak layer in the 35 - 50cm height range.

Green

Below the distinctive weak layers is a thin fusion crust with a hardness grade of 4 (pencil). However, the crust consists not only of fusion forms, but also partly of angular crystals. These are 0.5 - 1.5mm in size.

Below 31cm we see two more layers of angular and angular-rounded crystals with a grain size between 1 and 2mm and hardness grade 2 and 2-3.

Conclusion & interpretation regarding avalanche danger

The snow profile impressively confirms the warnings of the avalanche warning services. The constellation of snow slab (blue area) to weak layer (red area) is perfect here. The stability test shows a fracture including fracture propagation over the entire block at low loads.

But for us as winter sports enthusiasts, it's even worse: it's not just the properties of the snow slab and weak layer that match perfectly. At around 35 cm, the thickness of the snow slab is also perfect for triggering avalanches by humans. This is because from a thickness of the overlying snow slab - i.e. the snow layer above the weak layer - of around 75cm, the weak layers are no longer so easy to disturb with the weight of a person.

In addition, there are a few centimetres of loose fresh snow on the surface. The weak layers of old snow are not visible from the outside anyway, but here the fresh snow layer also hides the drift snow. This makes the situation even more insidious.

In summary: Where there is a layer of snow from the fall: Stay defensive and wait and see. The winter is still long and skiing in non-avalanche terrain can also be very nice!