Bisistal

In the northeast a considerable danger of wet avalanches will prevail.

Considerable danger of wet avalanches will prevail. As a consequence of the rain wet and gliding avalanches are to be expected from the late morning. Wet avalanches can release deeper layers of the snowpack and reach large size in isolated cases, especially on steep north facing slopes. The conditions are unfavourable for backcountry touring.

Moderate danger of dry avalanches will prevail. The somewhat older wind slabs are in some cases still prone to triggering at elevated altitudes. They are to be avoided as far as possible. Dry avalanches can additionally be released in deeper layers in isolated cases. Caution is to be exercised in particular in areas where the snow cover is rather shallow above approximately 2600 m on very steep north facing slopes.

Snowpack Particularly on high-altitude north-facing slopes, there are weak layers which are embedded in the near-surface section of the snow cover which are prone to triggering in some places. As a consequence of cooler temperatures during the last few days, the process of the snowpack becoming thoroughly wet has been brought to a halt. On east-facing, south-facing and west-facing slopes the snow cover was already thoroughly wet up to over 3000 m. On north-facing slopes thorough wetness of the snow cover extended up to between 2000 and 2500 m and was then brought to a halt. With increasingly high temperatures of daytime warmth and also rainfall, the near-surface layers of the snowpack will initially become further moistened. Moreover, as water seeps deeper down into the snow cover, particularly the deeply embedded weak layers (which are becoming wet for the first time this spring) will be additionally weakened. At heightened altitudes the snow depths on the northern flank of the Alps and in northern Grisons correspond to long-term medium values, in the Valais the snow depths are above the medium values over widespread areas. Further towards the south, the snow depths lie significantly below long-term medium values for this juncture of the season. Observed weather review Thursday, 27.04.2023 In the western and the southern regions, nocturnal skies on Wednesday night were predominantly clear. In the remaining regions of Switzerland there was a small amount of precipitation, subsequently the skies cleared up incrementally from the west. During the daytime hours on Thursday it was predominantly sunny. Fresh snow In the northern regions there was a few centimetres of fresh snow registered from region to region. Temperature At midday at 2000 m, between +5 °C in the western and the southern regions and +3 °C in the eastern regions. Wind Winds were blowing from westerly directions,

• during the nighttime hours predominantly at light strength;
• during the daytime hours slackening off and blowing mostly at light strength during the afternoon.

Weather forecast through Friday, 28.04.2023 During the nocturnal hours on Thursday night and during the daytime hours on Friday, skies are expected to be heavily overcast for the most part. Only in the central sector of the southern flank of the Alps will it be rather sunny starting in the morning. Fresh snow The snowfall level is expected to ascend from 2600 m up to 2900 m in the western regions and from 2000 to 2600 m in the eastern regions. Above those altitudes, the following amounts of fresh snow are anticipated:

• in the central and eastern sectors of the northern flank of the Alps, Prättigau, Silvretta, Samnaun: 5 to 15 cm;
• in the remaining regions of Switzerland, less; or else it will remain dry from region to region.

Temperature Temperatures are expected to rise further. At midday at 2000 m, between +9 °C in the western regions, +6 °C in the eastern regions, and +4 °C in the southern regions. Wind Winds will be blowing from westerly directions,

• generally at light to moderate strength;
• during the afternoon on the northern Alpine Ridge and in the western sector of the Main Alpine Ridge also at strong velocity.

Outlook through Sunday, 30.04.2023 Saturday Following a night of overcast skies on Friday, accompanied by precipitation in the northern regions more than anywhere else, it will be partly sunny in the western regions, rather sunny in the eastern and the southern regions during the daytime hours on Saturday. During the latter part of the day, cloud cover is expected to increase in general and, particularly in the western regions, additional showers are to be expected. The westerly winds will slacken off, they will be blowing predominantly at light strength during the course of the day. It is expected to remain mild. The danger of wet-snow avalanches will remain at elevated levels. Wet-snow and gliding avalanches can be expected on Friday night in the northern regions more than anywhere else as a consequence of rainfall up to 2700 m, and during the daytime hours in the case of sunshine. The danger of dry-snow avalanches could increase somewhat in the high alpine regions. Sunday The approaching developments in weather conditions are highly uncertain. Following a night of partly clear skies in the northern regions, it is expected to be partly sunny during the morning hours, during the afternoon it will become increasingly overcast. In the southern regions, skies will be overcast accompanied by precipitation. The snowfall level will lie at 2400 m. Winds will remain light, temperatures will remain mild. The danger of wet-snow and gliding avalanches is expected to remain at heightened levels. The danger of dry-snow avalanches will decrease.