Snow conditions 13.12.2017

General danger level - Wednesday, 13 December 2017

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

Main problem: new snow, weak layers

Danger pattern: Cooling after warm weather / warming after frost



Risk assessment

Avalanche danger is currently above about 1800 m MODERATE, 3rd degree, lower down LOW, 1st degree. Steep slopes and wind-loaded areas in the high mountains are dangerous, where individual slab avalanches of new, dry snow can release. You can trigger an avalanche even with a small additional load on steeper slopes and on wind slabs. Lower down, where it rained in recent days, the snow has frozen and stabilised upon cooling, and the amount of new snow that fell last night is too small to worsen the avalanche conditions.



Snow conditions

In the last 48 hours, the most snow has fallen above about 1800 m in the Julian Alps and western Karawanks, even more than 160 cm! Less elsewhere, specifically in the central Karawanks and Kamnik-Savinja Alps from 20 to about 50 cm, even less in the eastern Karawanks, only 10 to 20 cm. Lower down it rained for a long time, the snow settled and thinned, at the end of the precipitation about 10 cm of snow fell up to 1000 m elevation, and on Wednesday night it snowed even lower, but with little snow. In the high mountains, it mostly snowed on a crusty base, only in gullies was the old snow still soft. Therefore, there are weak layers in the snowpack in places. Strong southwesterlies created wind slabs and built cornices, ridges are heavily scoured. The snow is light and soft, lower down the layer of new snow is shallow.



Forecast weather development

On Wednesday there will be occasional light snowfall, but the amount of precipitation will be small. On Thursday it will be dry in most of our mountains, only in the western and southern Julian Alps and in the hills of northern Primorska and Notranjska there will be precipitation with snow line between 900 and 1200 m. Warmer air will flow in again and the freezing level will rise to about 1400 m elevation. On Friday it will be even warmer, freezing level at about 1900 m above sea level. Precipitation everywhere. Snow line at about 1400 m elevation, locally lower, in the afternoon and evening it will descend. Both on Thursday and Friday a strong southwesterly will blow.



Tendency of snow conditions

New snow has settled somewhat even in the high mountains. Today, Wednesday, due to cloudy and cold weather, the snowpack condition will be almost unchanged. On Thursday with warming, the snow will transform and settle faster, below the 0°C isotherm it will refreeze and also thin. The snowpack will slowly stabilise. On Friday new snowfall will again increase avalanche danger, new areas of wind slabs will form. In the high mountains avalanche danger will remain CONSIDERABLE, 3rd degree.



Next issue: Saturday, 16 December 2017



Source: ARSO