Hasliberg - Rosenlaui

Moderate avalanche danger will be encountered in some regions. Wind slabs require caution

Moderate avalanche danger will be encountered in some regions. Wind slabs require caution

As a consequence of new snow and a strong northerly wind, avalanche prone wind slabs formed. They are to be found in particular in gullies and bowls, and behind abrupt changes in the terrain. Avalanches can in some cases be released easily and reach medium size. The wind slabs are to be avoided in steep terrain.

As a result of the minor amount of fresh snow and northerly winds, relatively small-sized snowdrift accumulations were generated on Thursday. These drifts are expected to grow somewhat in frequency and size on Friday. The snowdrift accumulations are located on west-facing, north-facing and east-facing slopes, frequently atop a loose, expansively metamorphosed (faceted) old snowpack surface. Particularly on these slopes they are prone to triggering. The snowdrift accumulations constitute the major danger. Below that altitude the snowpack layering on the northern flank of the Alps and in the western part of the Lower Valais is favourable over widespread areas. Atop or beneath the rain crust which formed at the end of December there are weak layers evident; nevertheless these layers have proved relatively unlikely to trigger up to now. From the central part of the Valais over the northern part of the Ticino as far as Grisons, there are weak layers deeper down inside the snowpack. However, for a longer period of time there have hardly been any avalanche triggerings reported from these more deeply embedded layers.

In the northern regions skies were heavily overcast, accompanied by light, shower-like snowfall which extended down to low lying areas. In the Valais and in the southern regions it was partly sunny; in the Sotto Ceneri it was predominantly sunny. Fresh snow: By Thursday afternoon, the following amounts of fresh snow were registered above approximately 1000 m: - eastern Bernese Alps, central and eastern sectors of the northern flank of the Alps, northern Grisons: 5 to 10 cm; as much as 15 cm from place to place; - Jura region as well as the remaining regions of the Alps: only a few centimetres from place to place; in the southern regions it remained dry. Temperature: Temperatures dropped. At midday at 2000 m, -7 °C in the northern regions and -4 °C in the southern regions. Wind: - On Wednesday night, winds were predominantly light to moderate in strength, on the Simplon Pass and Bernina Pass frequently blowing at strong velocity, from northwesterly directions; - during the daytime in the eastern and southern regions at high altitudes, as well as in general in the Jura region, blowing at moderate to strong velocity, in the other regions of Switzerland blowing at light to moderate strength, from northerly to northwesterly directions. On Thursday night in the southern regions, skies will be predominantly clear, in the Valais partly clear. In the northern and eastern regions skies will be overcast accompanied by light snowfall extending down to low lying areas. During the daytime on Friday in the western and southern regions, it will be predominantly sunny. In the northern and eastern regions, a small amount of additional snowfall is expected on Friday morning, before it will subsequently become increasingly sunny from the west during the course of the day. Fresh snow: Between Thursday afternoon and Friday afternoon, the following amounts of fresh snow are anticipated: - central and eastern sectors of the northern flank of the Alps, northern Grisons: 5 to 10 cm; as much as 15 cm from place to place; - Jura region, western sector of the northern flank of the Alps, remaining parts of the Gotthard region, central Grisons, northern Engadine: only a few centimetres; in the other regions of Switzerland it is expected to remain dry. Temperature: At midday at 2000 m: between -8 °C in the western regions and -12 °C in the eastern regions, and -6 °C in the southern regions. Wind: - Jura region and western Prealps: moderate to strong Bise wind; - in the southern regions: moderate-to-strong velocity northerly foehn wind; - at high altitudes: on Thursday night in the eastern and southern regions, moderate to strong-velocity northerly wind, during the daytime on Friday blowing at moderate to strong velocity from northeasterly directions over widespread areas.

Saturday: In the northern and eastern regions skies will be predominantly overcast and in the eastern regions a few centimetres of snowfall is expected to extend down to low lying areas. In the Valais and the southern regions it will be rather sunny. At high altitudes a moderate to strong-velocity northerly to northeasterly wind will be blowing. Temperatures are expected to increase somewhat. Avalanche danger levels are not expected to change significantly. Sunday: It will be rather sunny in the mountains. The zero-degree level will lie at 2000 m. The northerly winds will slacken off. The danger of dry-snow avalanches will incrementally decrease. On steep sunny slopes, moist-snow slides from the fresh fallen snow are possible during the course of the day.