südliches Urseren

Moderate avalanche danger will be encountered over a wide area.

In some places avalanches can be released in the old snowpack and reach large size. These avalanche prone locations are to be found in particular in areas where the snow cover is rather shallow. As a consequence of new snow and a strengthening southwesterly wind, mostly small wind slabs will form in the course of the day. They are to be evaluated with care and prudence in particular in very steep terrain. High Alpine regions: The avalanche prone locations are to be found in all aspects. Backcountry touring and other off-piste activities call for careful route selection.

Snowpack At 2500 m altitude in the western and the northern regions there is 100 to 200 cm of snow on the ground over widespread areas, in the northern and furthermost western parts of the Valais as well as in the central and eastern sectors of the northern flank of the Alps there is as much as 300 cm of snow on the ground in some places. In the southern regions where there is very little snow, only 50 to 100 cm of snow is on the ground at this altitude. A cohesive, area-wide snow cover exists in the northern regions on north-facing slopes at 1200 to 1600 m, on south-facing slopes at altitudes 200 to 400 m higher up. In the southern regions the snow levels on north-facing slopes lie at 1600 to 2000 m, and on south-facing slopes at 2000 to 2400 m, also higher up from place to place. Inside the snow cover there are near-surface layers which are still prone to triggering, particularly on shady slopes and in transitions from shallow to deep snow. Furthermore, on west-facing, north-facing and east-facing slopes there are also weak layers evident deeply embedded inside the snow cover. In the inneralpine regions of the Valais and Grisons more than anywhere else, these weakened layers are frequently still prone to triggering, more than anywhere else in zones where the snow is shallow. As a consequence of fresh fallen snow and intensifying southwesterly winds, snowdrift accumulations will be generated on Thursday. On north-facing slopes, these snowdrifts will be deposited on top of a loose old snowpack surface above approximately 2600 m. As temperatures drop, the danger of wet-snow avalanches will decrease; isolated gliding avalanches continue to be possible, however. Observed weather review Wednesday, 19.04.2023 Skies on Tuesday night were partly clear. During the daytime hours on Wednesday it was predominantly sunny in the mountains to start with, accompanied by convective cloud build-up during the course of the day. During the afternoon hours in the eastern regions, skies became predominantly overcast. Fresh snow - Temperature At midday at 2000 m, between +3 °C in the western regions and +1 °C in the eastern regions, and +5 °C in the southern regions. Wind Winds were blowing at light to moderate strength from northerly to northwesterly directions. Weather forecast through Thursday, 20.04.2023 Nighttime skies on Wednesday will be partly clear in the Valais, in the other regions of Switzerland skies will be predominantly overcast accompanied by light precipitation. During the daytime hours on Thursday, skies will be variably cloudy to heavily overcast. To start with, precipitation is expected on the northern flank of the Alps and in Grisons, during the afternoon also reaching the Ticino. The snowfall level will descend from 1600 m down to 800 m in the northern regions, in the southern regions the snowfall level will lie at 1400 to 1800 m. Fresh snow Between Wednesday evening and Thursday afternoon the following amounts of fresh snow are anticipated in northern regions above approximately 1600 m, in southern regions above approximately 2000 m:

• central sector of the southern flank of the Alps, Val Bregaglia, Corvatsch, Bernina: 15 to 25 cm;
• northern flank of the Alps fron the eastern Bernese Alps into Liechtenstein: 10 to 15 cm;
• in the remaining regions of Switzerland, only a few centimetres.

Temperature Temperatures are expected to drop. At midday at 2000 m, to between -3 °C in the northern regions and 0 °C in the southern regions. Wind Winds will be blowing from westerly to southwesterly directions,

• at light to moderate strength on Wednesday night;
• at moderate strength at heightened altitudes during the daytime; at moderate to strong velocity on the northern flank of the Alps.

Outlook through Saturday, 22.04.2023 Friday On the Main Alpine Ridge from the Furka Pass as far as the Bernina Pass and southwards therefrom, 20 to 40 cm of fresh snow are expected to fall by Friday midday, as much as 50 cm from place to place. The precipitation is expected to spread over to the bordering northern regions, where 10 to 30 cm of fresh fallen snow is possible. The snowfall level in the southern regions will lie at 1600 m, in the northern and the eastern regions at 1200 to 1500 m. During the daytime hours in the western regions it will be predominantly sunny, in the eastern regions partly sunny, and convective cloud build-up is anticipated during the course of the day. The southerly to southwesterly winds will be blowing at moderate to strong velocity in the areas of precipitation during the nocturnal hours on Thursday, in the other regions winds will be blowing at light to moderate strength. Avalanche danger levels are expected to increase on Thursday night as a consequence of fresh snowfall and wind, significantly so in the major areas of precipitation on the Main Alpine Ridge and in the southern regions. Saturday Nighttime skies on Friday will be predominantly overcast. During the daytime hours on Saturday it will be quite sunny in the northern regions accompanied by cloudbanks, in the southern regions skies will be predominantly overcast. Temperatures are expected to rise. Danger of dry-snow avalanches will decrease. Danger of wet-snow avalanches is expected to increase during the course of the day.