südliches Urseren

Considerable avalanche danger will be encountered over a wide area.

The fresh snow and the sometimes large wind slabs are lying on top of a weakly bonded old snowpack. Single winter sport participants can release avalanches easily. These can release the weakly bonded old snow as well and reach large size in some cases. Whumpfing sounds can indicate the danger. Backcountry touring and other off-piste activities call for experience in the assessment of avalanche danger and caution.

In steep rocky terrain moist snow slides and avalanches are possible as a consequence of warming during the day and solar radiation.

Snowpack The huge amounts of snow which have fallen in the western and the northern regions since Thursday were deposited on top of soft layers of faceted crystals over widespread areas above approximately 2200 m. For that reason, fractures extending down to these deeply embedded layers are easily possible. In addition, the fresh fallen snow has been intensively transported by the strong to storm-strength westerly winds. Far-reaching snowdrift accumulations have been generated, including distant from ridgelines. The fresh fallen snow and freshly generated snowdrift accumulations tend to increase significantly with ascending altitude. Below 2200 m, the snow cover in the areas of precipitation is thoroughly wet from the rainfall, in the other regions of Switzerland the snowpack is moist up to approximately 2500 m due to the mild temperatures. Dry-snow avalanches which fracture and release at high altitudes can sweep away the entire thoroughly wet snowpack at altitudes below 2000 to 2500 m. The snow cover is only quite shallow, however. Observed weather review Saturday, 24.12.2022 During the nocturnal hours of Friday, intensive snowfall continued in the northern and the furthermost western regions. The snowfall level descended towards the end of this period of precipitation to nearly 1800 m in the western regions, to nearly 1500 m in the eastern regions. During the daytime hours on Saturday there was only a small amount of precipitation, but skies remained heavily overcast. In the furthermost southern regions it was predominantly sunny and dry. Fresh snow Between Friday afternoon and Saturday midday the following amounts of fresh snow were registered above approximately 2500 :

• furthermost western part of Lower Valais, northern Alpine Ridge west of the Wildstrubel, northern Alpine Ridge from the Aletsch regioin as far as Hausstock: 30 to 50 cm;
• remaining regions of the northern Alpine Ridge, remaining parts of Valais, northern Prättigau: 15 to 30 cm;
• in the other regions of Switzerland, less than 15 cm; in the furthermost south it remained dry.

All in all since the onset of this period of precipitation on Thursday afternoon until Saturday midday, the following amounts of fresh snow have been registered above approximately 2500 m:

• furthermost western part of Lower Valais as well as the northern Alpine Ridge west of the Wildstrubel: more than 1 metre;
• remaining parts of the northern Alpine Ridge and Lower Valais: 50 to 80 cm;
• remaining parts of Upper Valais, furthermost northern part of the Ticino and northern Prättigau: 30 to 50 cm;
• northern Grisons as well as Lower Engadine: 15 to 30 cm;
• in the other regions of Switzerland, less than 15 cm; in the furthermost south it remained dry.

Temperature At midday at 2000 m, between +3 °C in the southwestern regions and 0 °C in the northeastern regions. Wind Winds in the northern regions and in general at elevated altitudes were blowing at strong velocity from the west. Weather forecast through Sunday, 25.12.2022 It will be predominantly sunny and mild. The zero-degree level is expected to ascend to 3000 m. Fresh snow - Temperature At midday at 2000 m, between +7 °C in the northern regions and +3 °C in the southern regions. Wind Winds will be blowing at moderate to strong velocity, in some high alpine regions at storm-strength, from westerly directions. Outlook through Tuesday, 27.12.2022 Monday On Boxing Day it will be quite sunny to begin with. During the course of the day, cloud cover will increase from the northwest and in northern regions precipitation will set in during the afternoon. The snowfall level will descend from approximately 2000 m down to nearly 1600 m by evening. In the southern regions it is expected to remain dry and rather sunny. At elevated altitudes, a moderate to strong-velocity westerly wind will be blowing. The avalanche danger levels are expected to decrease slightly. Nevertheless, for winter sports enthusiasts in outlying terrain away from secured ski runs, the avalanche situation remains treacherous. Tuesday During Monday night in the western regions above 2000 m, and in the eastern regions above 1600 m, a small amount of snowfall is expected. On Tuesday morning the precipitation will come to an end and it will become rather sunny. Temperatures will drop somewhat, the zero-degree level will lie at 1700 m. Avalanche danger levels are not expected to change significantly