südliches Urseren

For those venturing off piste a critical avalanche situation will be encountered over a wide area

For those venturing off piste a critical avalanche situation will be encountered over a wide area

As a consequence of new snow and a storm force northwesterly wind, deep wind slabs formed. The new snow and wind slabs are lying on top of a weakly bonded old snowpack. Even single snow sport participants can release avalanches easily. Avalanches can be triggered in the old snowpack and reach very large size in isolated cases. Remotely triggered avalanches are possible. In addition further very occasional natural avalanches are possible. The conditions are critical for backcountry touring and other off-piste activities. This also applies in steep starting zones in areas close to the tree line. Caution and restraint are required. As a consequence of warming during the day and solar radiation moist loose snow avalanches are to be expected. Individual gliding avalanches are possible.

Monday’s winter storm brought precipitation over a wide area and transported large quantities of fresh and old snow. In locations situated some distance from ridgelines, sometimes large snow drift accumulations have formed. The fresh snow and snow drift accumulations are prone to triggering, and avalanches can be released easily. Distinct weak layers exist deeper in the snowpack in particular on west, north and east facing slopes. On the northern flank of the Alps these are mostly covered by thick layers of snow and therefore less prone to triggering. From southern Valais through northern Ticino to Grisons, in many places all the old snow near the ground is faceted. In these regions over the weekend several large avalanches, and in isolated cases very large avalanches, were triggered by people. Further releases of this kind remain possible.

On Sunday night, heavy precipitation commenced. The snowfall level initially rose from 800 m to approximately 1400 m before dropping to low altitudes. During the day it was very cloudy at first, and in the east snowfall persisted until the afternoon. In the west the precipitation ceased in the morning and it became increasingly sunny. In the south only a little precipitation fell, and during the day it was fairly sunny. Fresh snow: From Sunday afternoon until Monday afternoon above 1600 m: - Northern Alpine ridge, Valais excluding both the Visp valleys and the southern Simplon region, rest of the Gotthard region, northern Grisons, Silvretta, Samnaun: 25 to 40 cm - Jura, remaining regions on the northern flank of the Alps, Saastal, southern Simplon region, central Grisons, rest of Lower Engadine: 10 to 25 cm - Further south: 5 to 10 cm Because of the storm, the fresh snow was deposited very irregularly. Temperature: At midday at 2000 m: between -10 °C in the north and -7 °C in the south Wind: - In the north initially from the southwest to west, then from the northwest: strong to storm force, severe storm in the high Alpine regions. In the course of the afternoon easing from the west. - In the south, a strong northerly wind even in the lowlands In the east, cloudbanks will linger in the morning but it will be mostly sunny elsewhere. Temperatures will rise significantly from the west. Fresh snow: - Temperature: Increasing, at midday at 2000 m: between +2 °C in the southwest and -4 °C in the northeast Wind: - In the north, light to moderate from westerly directions - In the south and generally at elevated altitudes, moderate to strong from the north

On both days it will be sunny and mild. The zero degree level will rise towards 3500 m on Wednesday before falling to 2500 m again on Thursday. At elevated altitudes the wind will be light to moderate on Wednesday and moderate to strong on Thursday, from westerly directions. The danger of dry avalanches will decrease, but only slowly on shady slopes. In the inner Alpine regions in particular, the situation will remain critical for snow sport participants venturing off piste. Under the influence of solar radiation and daytime warming, the danger of wet snow and gliding avalanches will increase during each of the coming days.