Snow conditions 1. 4. 2024

General danger level - Monday, 1. 4. 2024
Danger is 3rd degree on the European five-level scale - CONSIDERABLE.
Main problem: wind slab, new snow, wet snow
Danger pattern: Cooling after warm weather / warming after cold
Danger pattern: Rain

Risk assessment
Avalanche danger is mainly in the high mountains above sea level around 2400 m CONSIDERABLE, 3rd degree, lower MODERATE, 2nd degree. On the highest peaks the snowpack is unstable especially in drifts that formed during snowfall with south and west wind. There slab avalanches can be triggered with minor loading. Between approximately 2000 and 2400 m the snowpack will be temporarily more stable due to cooling, but danger of cornice falls and gliding avalanches remains. In sunny weather on Tuesday and Thursday mornings the probability of spontaneous release of wet snow avalanches on the most sun-exposed slopes will increase.

Snow conditions
Since Friday in the Western Julian Alps up to the highest peaks it has at least briefly rained or wet snow has fallen, more than 60 cm of snow has fallen. Elsewhere above 2400 m it has been snowing continuously, up to 30 cm of snow has fallen. Most snow fell with strong south wind, at the end also with west wind, new snow drifts have formed. Between 2400 and 2000 m it first snowed, then with pronounced influx of warm air from the south it warmed up and snow turned to rain, so no new snow there today until 3 p.m. Below 2000 m it has been raining almost continuously everywhere, in the Western and Southern Julians a lot of rain fell, which soaked the old snowpack and reduced its stability. Thereby especially on steep slopes above 2000 m, where half a meter of snow fell a few days ago, wet snow avalanches released spontaneously. In the vicinity of the highest peaks, where it snowed, thunderstorms also appeared this afternoon. Today, Monday afternoon, it cooled slightly with the passage of the cold front; now the snow line is at approximately 1800 m and will drop a little more in the next hours. The snowpack has thickened on the highest peaks, new snow drifts have formed in northern and northeastern lee areas. Lower down the snowpack has been melting and settling, it is wet, only the top covered with dry snow. There is less and less snow in the mid-mountains. Thin snow cover on sun-exposed slopes starts only above around 1800 m or higher, in shady locations consolidated snowpack starts at sea level around 1400 m. Rainfall has also reduced the stability of cornices in the high mountains, which can collapse at unpredictable times.

Forecast weather development
Local precipitation - showers and thunderstorms - will reappear in the west after a short break today, Monday evening, and then spread towards the interior of the country. At midnight to Tuesday precipitation in the mountains will end, until then up to 10 cm of snow can fall above 1500 m. Then a strengthened northerly will blow temporarily, in the morning already a weak westerly. In the morning there will still be some clear skies, already midday especially in the north isolated showers and thunderstorms will form. The zero isotherm on Tuesday will be around 1800 m. On Wednesday morning sunny, during the forenoon clouding, southwesterly strengthening. Midday light precipitation will appear, above 1500 m snow. A few centimeters of snow will fall, which will not affect avalanche release dangers. On Thursday it will warm up, the zero isotherm will rise to around 2500 m. More sun and little wind.

Tendency of snow conditions
The snow that will fall above 1500 m on Tuesday night will not affect the avalanche release danger. The night northerly will somewhat redistribute it and deposit it in lee areas; snow drifts will presumably be well visible - the old, rain-soaked snow base contains considerable desert sand, in new drifts there will be less of it and there the snow will be whiter. Due to cooling the snowpack especially between 2000 and 2400 m will freeze and will therefore be temporarily less sensitive to additional loading - more stable. In sunny weather on Tuesday and Thursday mornings the probability of spontaneous release of wet snow avalanches will somewhat increase especially on steep eastern and southeastern slopes. Above 2400 m the main threats remain areas of wind slab especially near ridges. Despite temporary cooling the threats of cornice falls and gliding avalanche releases remain present also in the high mountains!

Next issue: Thursday, 4. 4. 2024

Source: ARSO