Pays d'Enhaut

Stormy weather and new snow: In the west a considerable avalanche danger will prevail

Stormy weather and new snow: In the west a considerable avalanche danger will prevail

As a consequence of new snow and a sometimes storm force westerly wind, avalanche prone wind slabs will form. They can be released even by a single winter sport participant. The number and size of avalanche prone locations will increase as the day progresses. By the middle of the day danger level 3 (considerable) will be reached. The wind slabs are to be bypassed in steep terrain. As the day progresses as the snowfall level rises there will be an increase in the danger of wet avalanches. In particular on north facing slopes small and medium-sized wet and gliding avalanches are to be expected below approximately 2000 m.

Fresh fallen snow and, to some extent, also old snow is being intensively transported over widespread areas by storm-strength westerly winds. Prior to the current snowfall the snowpack surface was massively marked by sun impact over widespread areas. Thus, bonding to the layers of fresh snow and fresh snowdrift accumulations is generally favourable. On the other hand, on north-facing slopes at high altitudes the snowpack surface was often expansively metamorphosed (faceted) and formed a weak snowpack base in those places. As a result of rainfall up to 2000 m, wet-snow and gliding avalanches can be expected. This will be the case particularly on north-facing slopes. In the inneralpine regions of Grisons and in some parts of the Valais the snowpack structuring on north-facing slopes continues to be weak; nevertheless, hardly any avalanches have been registered triggering from these deeply embedded layers for a longer period of time.

Following a night of predominantly clear skies it was sunny on Monday. Starting at midday, cloud cover moved in from the west. Fresh snow: - Temperature: At midday at 2000 m, +2 °C. Wind: Winds were blowing predominantly at light strength from southwesterly directions. On Wednesday evening, precipitation is expected to set in from the west. During the night and on Thursday during the daytime, precipitation is anticipated over widespread areas, most of all in western regions. The snowfall level during the night will lie at 1400 m, during the daytime it will ascend to nearly 2000 m. In Grisons only a small amount of precipitation is anticipated, in the furthermost southern regions it will remain dry. Fresh snow: Between Wednesday evening and Thursday afternoon, the following amounts of fresh snow are expected above approximately 2000 m: - furthermost western part of the Lower Valais on the French border and northern Lower Valais: 30 to 50 cm; - remaining parts of the Lower Valais and western sector of the northern flank of the Alps: 10 to 25 cm; - remaining regions of Switzerland: 5 to 15 cm; in the furthermost southern regions it will remain dry. Temperature: At midday at 2000 m, between -1 °C in the northern regions and +2 °C in the southern regions. Wind: Winds are intensifying, during the night they will be blowing at storm strength from westerly directions.

Friday: On Thursday night and during the daytime on Friday, storm-strength southwesterly winds will continue to blow and precipitation is expected over widespread areas which will be heavy in the western regions and on the northern flank of the Alps. In the southern regions and in the Engadine, variably cloudy skies are anticipated, during the afternoon light precipitation can be expected. The snowfall level will lie at approximately 2000 m. In the major areas of precipitation, large (in some cases, very large) wet snow avalanches can be expected below 2000 m. In the furthermost western part of the Lower Valais and probably also on the northern Alpine Ridge west of the Wildstrubel, Danger Level 4 (high) will be reached. Saturday: On Saturday, skies are expected to be heavily overcast for the most part and additional precipitation is anticipated. The snowfall level will descend during the Friday night down to approximately 600 m. In the northern regions the storm-strength westerly winds will slacken off during the course of the day. In the southern regions it will become increasingly sunny as a consequence of increasingly strong northerly winds. The danger of dry-snow avalanches continues to remain treacherous over widespread areas. However, as a consequence of descending temperatures, the danger of wet-snow avalanches will decrease.