Gruyère

Considerable avalanche danger will be encountered over a wide area.

The wind slabs of the last few days represent the main danger. The avalanche prone locations are to be found especially in gullies and bowls, and behind abrupt changes in the terrain. These avalanche prone locations are covered with new snow and are therefore barely recognisable. Avalanches can in some places be released and reach medium size. Careful route selection is recommended.

Snowpack The fresh fallen snow from this week has been transported by strong-velocity winds from varying directions and snowdrift accumulations which are prone to triggering have been generated over widespread areas. In the western regions the snowdrift accumulations are deep. From region to region the snowdrift accumulations have been blanketed by fresh snow and are thereby difficult to recognize. As a consequence of strong-velocity northerly winds in some places, fresh snowdrift accumulations are expected to be generated on Friday on the Main Alpine Ridge more than anywhere else. There are deeply embedded layers inside the snow cover which are expansively metamorphosed (faceted), particularly on north-facing slopes above 2200 m and on south-facing slopes above approximately 2800 m. These weak layers are prone to triggering, particularly in the southern Valais and in Grisons, as stability tests and avalanche releases during the last few days have confirmed. Observed weather review Thursday, 19.01.2023 The snowfall came to an end in the western regions on Wednesday night and it was subsequently rather sunny during the daytime hours on Thursday. In the eastern regions skies remained overcast and there was a small amount of intermittent snowfall. In the southern regions skies were overcast, but it remained dry. Fresh snow Between Wednesday afternoon and Thursday morning the following amounts of fresh snow were registered above 600 m:

• central and eastern sectors of the northern flank of the Alps: 10 to 20 cm;
• in the remaining parts of the western and the northern regions, only a few centimetres over widespread areas.

Temperature At 2000 m, -10 °C. Wind

• Winds in the northern regions were blowing at light to moderate strength from westerly directions;
• winds in the southern regions were blowing at moderate to strong velocity from northerly directions; moderate-strength foehn wind extended down into the valleys.

Weather forecast through Friday, 20.01.2023 Following a night of partly clear skies it will be quite sunny to begin with in the western and the southern regions on Friday. In the eastern regions skies will be overcast. During the course of the afternoon, cloud cover will move in over far-reaching areas. In the Prealps and in Grisons, a small amount of snowfall is possible. Fresh snow - Temperature At 2000 m, -12 °C in the northern regions and -9 °C in the southern regions. Wind

• Winds in the northern regions will be blowing at light to moderate strength from northerly directions;
• winds in the southern regions will be blowing at moderate strength, during the afternoon at strong velocity, from northerly directions;
• during the afternoon winds will be blowing at increasingly strong velocity from northerly directions also in the other parts of the Main Alpine Ridge.

Outlook through Sunday, 22.01.2023 Saturday In the northern regions skies will be variably cloudy and a small amount of snow is expected to fall from region to region. In the central and eastern sectors of the northern flank of the Alps, 5 to 10 cm of fresh snow is anticipated. In the southern regions and in southern Valais it will be quite sunny. At high altitudes a moderate to strong-velocity northeasterly wind will be blowing. It is expected to remain cold. As a result of winds, freshly generated snowdrift accumulations will be formed which could increase avalanche danger levels somewhat from region to region. Sunday In the northern regions skies will be heavily overcast for the most part and during the course of the day intermittent light snowfall will set in from the east. In the Valais and in the southern regions it will be rather sunny. It is expected to remain cold. Avalanche dangers are not expected to change significantly.