Report | How do SLF observers work in the field?

We actually wanted to do something together in the height of winter, when the avalanche situation is tricky and the snow cover offers something "exciting" to see. But we don't manage to find a date together and so it ends up being the end of March. There has been virtually no precipitation for 3 weeks and the avalanche bulletin points to a classic spring situation with a diurnal cycle. However, there are isolated danger spots in the old snow in the high north and east sectors. The conditions are actually rather safe, so I wonder what we'll find in the snowpack.

Reto picks me up by car and during the 40-minute drive to Savognin I realise how enthusiastic he is about his job. Not just about working in the snow, but about off-road work in general. Reto's main job is as a geologist in a local engineering office, so on the car journey I learn all sorts of exciting things about the "small" crumbling hills in Domat/Ems, which were left behind by the Flims landslide a long time ago. And about the current landslide near Brienz, which is not only causing problems for the Albula road and the route of the Rhaetian Railway, but is also threatening the village of the same name.
Reto has been making snow profiles for the SLF for more than 10 years. He joined the organisation as a long-standing terrain observer after completing a multi-week internship at the SLF and subsequent training.

Now it's time to dig. A wall a good 3 metres wide is cleared down to the ground. While digging, we place the snow thermometer on the snow surface, protected from the sun. We have already recorded the air temperature.

When creating the hand profile, we take a very close look at the individual layers, determine the moisture of the snow, grain type and size, the hardness of the individual layers and measure the temperature every 10cm at the top and every 20cm further down. You can find a detailed article on creating and interpreting snow profiles in this snow flurry.

On the surface we find a thin layer of surface frost, which doesn't really play a role at the moment, but could become a problem if there is a large overlay of shoots and fresh snow. This is followed by several layers, which become firmer towards the bottom at around 30 cm. The potentially weak layer follows below this slap: angular, large crystals. Sometimes even bucket crystals.

We take a close look under the magnifying glass: The largest ones are up to 4mm in size. The crystals here are barely connected to each other and trickle towards us like coarse sugar as we dig. Further down, the layers tend to become firmer again. Once everything has been noted, we uncover two ECTs (extended column test) on the wall. A block measuring 30 x 90 centimetres is uncovered in each case. Why two? Because it is quick, an identical or very similar result increases the significance and the two ECTs next to each other are practically the same width as the slide block.

--> On to the next page! -->

Now Reto throws 10 wrist strikes and then takes the first blow from the elbow. Zack! On the 11th stroke in total, the weak layer we had previously identified collapses along its entire length. Reto looks at me, laughs and is almost a little pleased that his hunch has come true. On the second ECT, the same layer collapses on the 3rd stroke from the elbow.

After we have cut off the 1.5 x 2 metre slide block at the back with a cord, Reto puts on his skis and carefully climbs into the upper third of the block. Now he bobs three times without jumping. On the first jump, the whole block slides off again. It's the same shift as the 2 ECTs before. Everything is once again recorded exactly in the field book. If you were to find this structure on a large scale, the risk of avalanches should certainly not be underestimated. However, as we have already observed on the approach that the slap is missing in many places on the weak layer, the danger spots are very sporadic and not widespread.

A detailed explanation of the individual stability tests can be found here.

Every slope profiler creates profiles in their own region. When Reto is not travelling with his deputy Thomas on the Pizol, he is out with friends in the inner Alpine regions of Graubünden. Like the other profilers, Reto does the whole thing more or less on a voluntary basis. He receives a small expense allowance as well as travel expenses and, in our case, the lift ticket reimbursed.

For me, this marks the end of a very exciting trip. As a ski instructor and snow sports enthusiast, I read the bulletin almost every day. I find it fascinating to see what's behind it and what's going on in the snow. Reto and I are definitely making an appointment for next winter, when there is a lot of snow and the avalanche risk is a little more difficult to assess. I'm looking forward to it and will report back in the form of a condition report or a continuation of this report.

Thanks of course to SLF and Reto for making it possible!