Bisistal

As a consequence of new snow and wind a considerable avalanche danger will be encountered in some regions.

The fresh snow of the last few days and the wind slabs can be released by a single winter sport participant in some cases. The wind slabs are covered with new snow in some cases and therefore difficult to recognise. Avalanches can in many cases reach medium size. The number and size of avalanche prone locations will increase with altitude. In the afternoon as a consequence of new snow and strong wind there will be an appreciable increase in the avalanche danger. Experience in the assessment of avalanche danger is required.

Snowpack On each of the recent days some snow has fallen at elevated altitudes, so that a fairly large quantity of fresh snow is now lying in the high Alpine regions. From midday on Tuesday, intense snowfall and strong wind will give rise to large snow drift accumulations. Underneath the fresh snow of recent days the old snowpack is thoroughly wet below approximately 2700 m on north facing slopes, and up to more than 3000 m in the other aspects. In particular in southern Valais and in Grisons, as well as locally in the other regions, distinct weak layers still exist deep in the old snowpack. Observed weather review Monday, 15.05.2023 The south was partly sunny. Otherwise it was often cloudy and precipitation fell over a wide area; above 1800 to 2200 m it fell as snow. Fresh snow Between Sunday afternoon and Monday afternoon the following amounts of snow fell above 2600 m:

• Northern Alpine ridge from the eastern Bernese Oberland into Liechtenstein 10 to 20 cm; from the Reuss into the Glarus Alps up to 30 cm
• Elsewhere: up to 10 cm, but largely dry in the south

Temperature In the middle of the day the zero degree level will be between 2200 m in the north and 2700 m in the south Wind Frequently moderate from the north Weather forecast through Tuesday, 16.05.2023 The night sky will be partly bright in the south, but otherwise overcast. During the day it will be very cloudy everywhere. There will be light precipitation everywhere except in the south; on the northern Alpine ridge in the afternoon the precipitation will be intense. The snowfall level will be approximately 2000 m. Fresh snow Between Monday afternoon and Tuesday afternoon above 2600 m:

• Northern Alpine ridge: 10 to 20 cm over a wide area, but up to 30 cm from the eastern Bernese Oberland into the Glarus Alps
• Elsewhere: up to 10 cm, but largely dry in the south

Temperature In the middle of the day the zero degree level will be between 2200 m in the north and 2600 m in the south Wind There will be a northeasterly wind:

• Light to moderate during the night
• Moderate, sometimes strong during the day

Outlook through Thursday, 18.05.2023 Wednesday On Tuesday night, heavy precipitation will fall in the north. During the day there will be a little further precipitation only in the northeast and in southern Upper Valais. The far west will be partly sunny, but it will remain very cloudy elsewhere. The snowfall level will drop to approximately 1400 m. Approximately 20 to 40 cm of snow will fall above 2200 m on the northern Alpine ridge and, in some cases, in northern and central Grisons as well. The northeasterly wind will be sometimes storm force on Tuesday night on the main Alpine ridge, otherwise moderate to strong. The avalanche danger will increase over a wide area on Tuesday night. In particular on the northern Alpine ridge, medium-sized to large natural avalanches are to be expected at elevated altitudes. Those engaging in backcountry ski touring must dispose of extensive experience in the assessment of avalanche danger, and exercise restraint. Thursday There will be variable cloud with prolonged bright spells in the north in particular. In the south a little precipitation may fall. The wind will ease to become light to moderate, and the zero degree level will rise to 2500 m. Although the danger of dry avalanches will decrease, the situation will remain precarious for those engaging in backcountry ski touring. Solar radiation is expected to give rise to a large number of moist snow avalanches; on the northern Alpine ridge these may be quite large in some instances.