Increase in avalanche danger as a consequence of the new snow.
From midday as the snowfall becomes more intense there will be an appreciable increase in the avalanche danger to level 3 (considerable). The fresh snow as well as the wind slabs that are forming during the snowfall will be deposited on a weakly bonded old snowpack in particular on west, north and east facing slopes above the tree line. Especially here avalanches can be triggered in the faceted old snow and reach medium size. With the onset of the intense snowfall, the natural avalanche activity will increase. Especially in places where the wind is stronger the avalanche danger is greater. The number and size of avalanche prone locations will increase with altitude.
Snowpack
dp.5: snowfall after a long period of cold dp.6: cold, loose snow and wind
Up to 10 cm of snow has fallen since Saturday. 15 to 30 cm of snow, and even more in some localities, will fall above approximately 1500 m. As a consequence of a gusty wind from southerly directions, soft wind slabs will form. These will be deposited on a weakly bonded old snowpack above the tree line. The old snowpack is faceted and weak; its surface consists of faceted crystals. This applies especially in shady places that are protected from the wind. The old snowpack will be subject to considerable local variations.
Tendency
The new snow and wind slabs remain prone to triggering.
Danger level
treeline
Avalanche Problem
Wind slab
Treeline
Persistent weak layer
Treeline
The new snow and wind slabs of the last few days must be evaluated with care and prudence.
The fresh snow as well as the mostly small wind slabs that are forming over a wide area are in some cases prone to triggering. These can be released in the weakly bonded old snow by a single winter sport participant. Caution is to be exercised in particular on very steep shady slopes, as well as adjacent to ridgelines and in gullies and bowls in particular above the tree line. Mostly avalanches are small. The snowpack will be generally subject to considerable local variations. Weak layers in the old snowpack necessitate caution and restraint. Apart from the danger of being buried, restraint should be exercised in particular in view of the danger of avalanches sweeping people along and giving rise to falls.
Snowpack
dp.6: cold, loose snow and wind dp.1: deep persistent weak layer
The snowpack will be generally subject to considerable local variations. In some regions 20 to 40 cm of snow has fallen above approximately 1200 m. The fresh snow and the wind slabs must be evaluated with care and prudence in particular on steep shady slopes. The old snowpack is faceted. Individual weak layers exist in the bottom section of the snowpack on wind-protected shady slopes.
