Pays d'Enhaut

In the west and in the north a very critical avalanche situation will be encountered in some regions

In the west and in the north a very critical avalanche situation will be encountered in some regions

As a consequence of new snow and a moderate to strong northwesterly wind, further wind slabs will form. These are prone to triggering. Natural avalanches are to be expected. Avalanches can be triggered in near-ground layers and reach very large size. This applies especially on west, north and east facing slopes above approximately 2000 m. Exposed parts of transportation routes can be endangered occasionally. Snow sport activities outside marked and open pistes call for very extensive experience in the assessment of avalanche danger and great restraint. Below approximately 2000 m medium-sized to large gliding avalanches are possible. Slides can occur on cut slopes.

In the lower part of the snowpack, weak layers with expansively metamorphosed (faceted) crystals are evident on west-facing, north-facing and east-facing slopes above approximately 2200 m in nearly all regions of Switzerland. From central Valais as far as Grisons as well as generally in spots where the snow cover is shallow, the snowpack layering is most unfavourable. In the western part of Lower Valais and on the northern flank of the Alps, the weak old snowpack is frequently overlain with thick fresher layers. In general, avalanches can most easily be triggered in spots where the snowpack is shallow. As a result of strong to storm-strength winds, from southerly directions to start with, subsequently from northerly to northwesterly, a great deal of snow was transported on Friday and will be continue to be transported on Saturday as well. Wide-ranging snowdrift accumulations are expected to generate which will be easily prone to triggering in some places.

Following a brief phase of clear skies on Thursday night, a new round of snowfall set in during the early morning hours of Friday in the western regions. The precipitation spread to the southern and the eastern regions during the later morning hours on Friday. Fresh snow: Between Thursday afternoon and Friday afternoon: - western and northern parts of Lower Valais, Vaud Alps: 20 to 40 cm; - Jura region, remaining parts of northern flank of the Alps, remaining parts of Lower Valais: 10 to 20 cm; - remaining parts of Valais, Grisons, Ticino: only a few centimetres. Temperature: At midday at 2000 m, between -5 °C in the northern regions and -9 °C in the southern regions. Wind: - Winds in the northern regions will be blowing at increasing strength from southerly directions on Thursday night, foehn wind is expected in the northern Alpine valleys; will gradually slacken off to moderate to strong velocity during the course of the day, blowing from westerly directions; - winds in the southern regions will be light, blowing at moderate strength at high altitudes, from southerly directions. In the northern regions, skies will be heavily overcast and snowfall is anticipated which will be deposited as far down as low lying areas. In the furthermost western regions and in central Valais, bright intervals are possible during the afternoon; on the southern flank of the Alps skies will be predominantly sunny. Fresh snow: Between Friday afternoon and Saturday afternoon: - Jura region, furthermost western part of Lower Valais, northern flank of the Alps: 20 to 30 cm; - remaining parts of Lower Valais: 10 to 20 cm; - Upper Valais, northern and central Grisons: 5 to 15 cm; - southern Grisons, less; on the southern flank of the Alps it will remain dry. Temperature: At midday at 2000 m, between -9 °C in the northern regions and -5 °C in the southern regions. Wind: - In the northern regions, blowing at strong velocity from northwesterly directions during the nocturnal hours and the morning; slackening off during the course of the day, then shifting to northerly, but on the Main Alpine Ridge persisting at strong to storm strength until the afternoon. - In the southern regions, blowing at moderate strength during the night, at strong velocity during the daytime, and at storm strength at high altitudes, from northerly directions.

Sunday: Following a night of temporarily clear skies on Saturday night, skies in the northern regions will be overcast on Sunday; in the Valais and in the southern regions, predominantly sunny. Temperatures are expected to rise noticeably. The northerly winds will continue to blow at predominantly strong velocity at high altitudes and in the southern regions. In the western and the northern regions the danger of naturally triggered avalanches will decrease. For winter sports enthusiasts venturing beyond the secured ski slopes into backcountry terrain, the avalanche situation remains critical over widespread areas. Monday: Between Sunday and Monday in the eastern regions, a small amount of precipitation is anticipated. During the daytime on Monday it will be sunny. Temperatures are expected to rise further, by midday reaching -4 °C at 2000 m in the western and southern regions, and -2 °C in the eastern regions. Winds will be blowing at light to moderate strength from northerly directions during the daytime. As a result of significantly higher temperatures, the avalanche situation will remain critical to begin with.