südliches Urseren

Increase in avalanche danger as a consequence of new snow and wind

Increase in avalanche danger as a consequence of new snow and wind

The fresh wind slabs are in some cases prone to triggering. They are to be avoided in steep terrain. Additionally in isolated cases avalanches can also be released in the old snowpack and reach medium size. These avalanche prone locations are barely recognisable, even to the trained eye. Careful route selection is important.

Fresh and drifting snow will be deposited on a variable old snowpack that has been influenced by rain, wind and the sun. In the regions on the northern flank of the Alps and the areas of Lower Valais and Grisons where a lot of fresh snow will fall, sometimes large snow drift accumulations will form. In the other regions, the snow drift accumulations will more likely be small to medium-sized. The fresh snow drift accumulations are prone to triggering. Slab avalanches are unlikely to be released in deeper layers on the northern flank of the Alps. From central Valais through northern Ticino to Grisons, faceted and loosely bonded layers exist in the snowpack. These are lying either directly underneath the rain crust that formed at the end of December, or they are embedded deeper in the snowpack. At elevated altitudes, these weak layers remain prone to triggering in some instances.

During Monday night snow fell at times in the north and in Valais in particular. By the morning the snowfall level had risen to 2200 m. During the day it was mostly dry but frequently cloudy. In the regions exposed to the foehn there were occasional bright spells. Fresh snow: From Monday afternoon until Tuesday morning above approximately 2400 m: - Extreme west of Lower Valais, Aletsch region: 5 to 15 cm - Rest of the northern Alpine ridge, rest of Valais: a few centimetres Temperature: At midday at 2000 m: between +4 °C in the north and -1 °C in the south Wind: - Strong over a wide area, storm force at times in the north, from the southwest - In Ticino, light to moderate from the south During the night, snow will begin to fall over a wide area. The snowfall level will drop to low altitudes. Around midday it will become increasingly dry from the west; snowfall will persist until the evening only in Engadine. Ticino will become sunny as the day progresses. Fresh snow: From Tuesday evening until Wednesday evening above approximately 1600 m: - Northern flank of the Alps, northern and extreme west of Lower Valais: 20 to 30 cm, but locally as much as 40 cm from Chablais to Wildstrubel - Elsewhere: 10 to 20 cm over a wide area; up to 10 cm in southern Upper Valais and in Ticino Temperature: Becoming significantly colder to reach between -11 °C in the north and -5 °C in the south at midday at 2000 m Wind: - During the night, mostly strong southwesterly - During the day on the main Alpine ridge and to the south, strong, otherwise mostly moderate, from the north

Thursday: A little snow will fall in the north, even in the lowlands. In the afternoon it will become increasingly dry and the weather will brighten up from the west. It will be quite sunny in the south. Cold weather will persist. At elevated altitudes and in the south, the wind will be moderate to strong from the north to northeast. The avalanche danger will not change significantly. Friday: On Friday cloud will build up from the west. It will remain sunny the longest in the east and south. The wind direction will revert to westerly. The avalanche danger will decrease a little.