Snow conditions 26.2.2020

Danger is 3rd degree on the European five-level scale - CONSIDERABLE.

Main problem: new snow, drifted snow

Danger pattern: Cooling after warm weather / warming after frost



Risk assessment

Avalanche danger is rapidly increasing across all our mountain areas due to snowfall and new snow. Above about 1700 m a.s.l. or where there was previously an old snow cover, the danger will mostly be CONSIDERABLE, 3rd degree. Steeper slopes and places with drifted snow will be dangerous. On wind-exposed sites, where new snow is drifted down to the old base, there is still danger of slides.



Snow conditions

The old snowpack is well transformed and hard, with 5 to about 30 cm of new snow on it, depending on altitude, more snow in the high mountains of the western and southern part of the Julian Alps. The southwest wind created drifts, but the wind is turning northerly, so new drifts will form on southern slopes. New snow in the high mountains has not bonded well to the hard base, so there is a weak layer under the new snow. Snow conditions will continue to change during the day today.



Forecast weather development

Today it will snow in the mountains, the snow line will drop from initial about 1800 m sometimes even to lowlands. Northerly winds will blow. At night precipitation will cease, tomorrow partly clear. Southwest wind will blow. In the afternoon it will gradually cloud over from the west and in the night to Friday there will be transient minor precipitation again especially in Notranjska and northern Primorska. Snow line mostly around 800 m a.s.l. On Friday it will partly clear up. A strong, locally gale-force northerly wind will blow.



Tendency of snow conditions

Avalanche conditions will deteriorate. Due to snowfall, avalanche danger will increase everywhere and be CONSIDERABLE, 3rd degree especially in high mountains above about 1700 m a.s.l., but this altitude greatly depends on how high the old snow base was. Drifts will form this morning on northern, in the afternoon on southern slopes, tomorrow, with the southwest wind, again on northern sides of ridges and saddles. The weak layer under the layer of new snow will persist, as it will remain cold until Friday, freezing level mostly around 1000 m a.s.l. Therefore, especially on steeper slopes, you can quickly trigger a slab avalanche with minor snowpack loading at sites with drifted snow, and from steep slopes especially today and tomorrow unbonded dry snow slabs can release spontaneously. On wind-exposed ridges, where new snow is heavily drifted, there will be danger of slides.



Next issue: Saturday, 29.2.2020



Source: ARSO