Snow conditions 4. 4. 2024

General avalanche danger level - Thursday, 4. 4. 2024
The danger is level 2 on the European five-level scale - MODERATE.
Main problem: wind slab, wet snow
Danger pattern: cooling after warm weather / warming after cold
Danger pattern: spring situation

Risk assessment
The avalanche danger is MODERATE, level 2. On higher summits, the snowpack is unstable mainly in wind slabs formed during snowfall with south and west winds. There, a slab avalanche can be triggered with a large load. Below about 2400 m, the snowpack is more stable as it has frozen solid after the last rainfall. There, wet snow avalanches can release during the day on sun-exposed slopes. The danger will increase from day to day until Sunday due to the pronounced thaw!

Snow conditions
After cooling following the last rainfall, a rain crust so thick formed on the snowpack surface below 2400 m that it supports the weight of a person - risk of slipping exists. On Tuesday, snow softened during the day only on sun-exposed slopes, remaining frozen on shaded ones. Wednesday was cloudier, so snow softened more slowly or later. A few centimeters of snow fell in places. The snowpack below 2400 m is stable until the entire rain crust softens due to daytime thaw from the sun. Then the probability of wet loose snow avalanches increases, as well as gliding avalanches and cornice falls. Due to the high content of desert dust, snow on sun-exposed slopes softens faster than usual for this time. On the highest summits, snow is less stable in wind slabs, where a slab avalanche can be triggered by loading.

Forecast weather development
An exceptionally warm weekend lies ahead, the zero isotherm will rise above 4000 m by Sunday, around 15 °C at 2000 m on Sunday midday. On Thursday and Friday, even more humid air will flow from the southwest, so it will be cloudy especially in the Soča mountains, and cumulus clouds will form elsewhere during the day. Especially in the Julian Alps, a shower may form in the afternoon. The zero isotherm will rise to 3000 m by Friday. On Saturday and Sunday, the air will be dry, the atmosphere calm, mostly sunny everywhere. A thunderstorm may form in the high mountains on Sunday afternoon. From Sunday afternoon onward, the air will contain some desert dust, more on Monday and Tuesday, so visibility will be somewhat reduced.

Trend in snow conditions
With pronounced dry warming, the danger will increase most on sun-exposed slopes, where snow will become wet during the day due to the sun up to the highest summits. There, wet loose snow avalanches may release especially on steep slopes. Surface snowpack softening will be somewhat faster than usual with pure white snow due to high desert dust content. At night, despite high temperatures, a crust will likely form on the snowpack surface due to low air humidity, but it will be thinner each night with rising air temperatures. Therefore, it will soften earlier each morning, and the snowpack will become unstable earlier. The probability of unpredictable gliding avalanches and cornice falls will also increase. On shade-exposed slopes of the highest summits, snow will likely remain dry, with wind slabs near ridges remaining the main threat.

Next issue: Sunday, 7. 4. 2024

Source: ARSO