südliches Urseren

Considerable avalanche danger will be encountered over a wide area.

The new snow and wind slabs of the last few days are lying on the unfavourable surface of an old snowpack. Single winter sport participants can release avalanches. Avalanches can in some cases release the entire snowpack and reach medium size. Backcountry touring and other off-piste activities call for experience in the assessment of avalanche danger.

Snowpack As a consequence of strong-velocity westerly winds and a small amount of fresh fallen snow, snowdrift accumulations were generated in many places on Thursday and on Friday. These snowdrift masses are still prone to triggering in some places. The fresh snow and freshly generated snowdrifts in western and northern regions from the beginning of the week are settling and stabilising to an increasing degree, nevertheless can still be triggered from place to place. In the more deeply embedded layers inside the old snowpack there are expansively metamorphosed (faceted) and loosely-packed layers evident. These layers are prone to triggering, particularly in the regions ranging from southern Valais over the Gotthard region as far as Grisons. In the remaining regions of Switzerland such layers occur more seldom or are no longer prone to triggering. The weakenend layers are to be found on north-facing slopes above 2200 to 2400 m and on south-facing slopes above approximately 2800 m. Observed weather review Friday, 13.01.2023 In the northern regions skies were heavily overcast accompanied by bright intervals in the inneralpine regions more than anywhere else. There was some intermittent snowfall registered above approximately 1300 m. In the southern regions it was predominantly sunny. Fresh snow Between Thursday afternoon and Friday midday the following amounts of fresh snow were registered above 1500 m:

• northern flank of the Alps, Valais and Jura region: a few centimetres;
• in the other regions of Switzerland it remained dry for the most part.

Temperature At midday at 2000 m, -1 °C. Wind Winds on the northern flank of the Alps as well as in general at elevated altitudes were blowing strong and intermittently at storm strength from westerly directions; in the other regions of Switzerland winds were blowing mostly at moderate strength. Weather forecast through Saturday, 14.01.2023 On Friday night a small amount of snowfall is anticipated above 1000 m in the northern and the eastern regions more than anywhere else. During the daytime on Saturday in the northern regions skies will be predominantly overcast accompanied by sunny intervals in the inneralpine regions of Grisons more than anywhere else. In the southern regions it is expected to be quite sunny. Fresh snow Between Friday midday and Saturday morning, the following amounts of fresh snow are anticipated above 1500 m:

• northern flank of the Alps, Lower Valais, northern Grisons: 5 to 15 cm; as much as 20 cm in the eastern sector of the northern flank of the Alps;
• Upper Valais, central Grisons, Engadine and Jura region: only a few centimetres;
• it is expected to remain dry on the southern flank of the Alps.

Temperature At midday at 2000 m, between +2 °C in the northern regions and -2 °C in the southern regions. Wind

• Winds on the northern flank of the Alps and in general at elevated altitudes will be blowing at strong velocity from western directions;
• during the nocturnal hours on the southern flank of the Alps blowing at strong velocity from northwesterly directions;
• in the other regions of Switzerland blowing mostly at moderate strength.

Outlook through Monday, 16.01.2023 On Saturday night in the northern and the western regions, precipiation is expected to set in which will subsequently intensify on Sunday. The snowfall level will ascend on Saturday night to approximately 2000 m in the northern regions, subsequently descend down to low lying areas during the course of the day on Sunday. Winds at high altitudes will be blowing at strong to storm strength from westerly directions. Following a dry phase on Sunday night, skies will be predominantly overcast during the day on Monday. Intermittently, snowfall is anticipated. All in all on Sunday and Monday in the Jura region as well as on the northern flank of the Alps, 15 to 30 cm of fresh snow is anticipated, in the furthermost western part of the Lower Valais more than 50 cm of fresh snow is possible. As a result of the fresh snow and strong-velocity winds, avalanche danger levels are expected to increase in the northern regions, significantly so in the western regions. In Grisons and on the southern flank of the Alps, avalanche danger levels are not expected to change significantly.