Snow conditions 10. 3. 2025

General avalanche danger level - Monday, 10. 3. 2025
Danger is level 3 on the European five-level scale - CONSIDERABLE.
Main problem: weak layers, wet snow, wind slab
Danger pattern: Rain

Risk assessment
Avalanche danger above 1800 m is CONSIDERABLE, level 3, lower down MODERATE, level 2. In the high mountains new snow deposits will form with the southwesterly wind, where a dry slab avalanche may be triggered by small additional load. Persistent weak layers hidden in the old snow continue to be a threat; additional loading from new precipitation and wind-drifted snow will overload them locally, medium-sized and large dry slab avalanches will release spontaneously. Below 1800 m wet loose snow avalanches will release due to rainmelt. All previous threats are joined this week by further stability reduction due to rainmelt, conditions will be unfavourable and highly variable, demanding.

Snow conditions
In warm weather the snowpack on sun-exposed aspects has rapidly transformed and melted, pronounced sun-exposed slopes are locally completely bare up to 1800 m. Monday night was warm and humid, snow refroze only above approx. 1800 m. Lower down snow on sun-exposed and shady aspects remained wet, now further saturated by rain. Higher up snow on sun-exposed aspects is crusted, on shady aspects still dry.

Forecast weather development
Today, Monday, mostly cloudy with precipitation passing across the country by midday. Towards the end precipitation will become convective, showers and possibly thunderstorms. Snow above 2000 m, with stronger precipitation slightly lower. Above 2000 m in Southern and Western Julian Alps up to 30 cm snow, elsewhere up to 20 cm. After end of precipitation, afternoon, southwesterly will strengthen; on the coastal side of the alpine-Dinaric barrier it will remain cloudy, on the inland side cloudiness will break in the afternoon and evening. Overnight to Tuesday clearing, only some transparent high cloud remains, wind calming by morning. Tuesday morning clouding over again with renewed southwesterly strengthening, occasional precipitation in Julian Alps. Wednesday and Thursday cloudy and foggy, on the west mostly raining, above 1800 m snowing. By Friday morning above 1800 m another approx. 30 cm snow, in Western and Southern Julian Alps possibly more than 50 cm. Temperatures similar all days, at 1500 m +3 °C, at 2000 m around 0 °C.

Trend in snow conditions
Below approx. 1800 m due to rain today, Monday, wet loose snow avalanches will release spontaneously, possibly also some full-depth slides. Snowpack will locally be saturated to the ground. High mountains remain wintry. New snow will likely bond well to the surface, less stable snow in fresh wind slabs formed by southwesterly. There a small dry slab avalanche can release already with small additional load. Overnight to Tuesday the surface of wet snowpack will refreeze and temporarily stabilise - until next rain Tuesday evening. With precipitation on Wednesday and Thursday probability of spontaneous release of wet loose snow avalanches below 1800 m will increase again. Above the snow line new wind slabs will form. Persistent weak layers of faceted crystals and depth hoar will remain in high mountains even after deterioration; buried deeper under the snowpack surface (50-80 cm), they will be harder to overload, but if overloaded the avalanche will be deeper, larger. With precipitation and wind snow transport today Monday and then Wednesday and Thursday natural overloading of these weak layers will occur in many places, therefore spontaneous release of medium-sized and large dry slab avalanches is expected in high mountains. Overloading of the deep weak layer can also be caused by pressure from release of a smaller superficial storm slab avalanche, hence chain-reaction avalanche release possible. Such snowpack structure is not characteristic of typical winters in our mountains, therefore we have little experience with it. It is essential to apply measures that reduce snowpack loading when crossing, especially on steep slopes, near ridges, at gully outlets and below walls.

Next issue: Thursday, 13. 3. 2025

Source: ARSO