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Avalanche bulletin through Sunday, 23 April 2017

In the north and in the east a moderate avalanche danger will be encountered over a wide area

Edition: 22.4., 17:00 Next update: 23.4., 18:00 Validity

In the north and in the east a moderate avalanche danger will be encountered over a wide area
Edition: 22.4.2017, 17:00 / Next update: 23.4.2017, 18:00
Snowpack
In northern and eastern regions, the fresh fallen and freshly drifted snow from this week has settled and consolidated only very incrementally due to the persistently low temperatures. Particularly on steep, north-facing slopes, the snow is still loosely-packed and, in some places, prone to triggering. In addition, as a result of the northwesterly winds on Saturday, fresh snowdrift accumulations have formed in high alpine regions more than anywhere else. During the nights, a melt-freeze crust forms which on south-, west- and east-facing slopes is capable of bearing loads. In western and southern regions the snowpack surface is generally capable of bearing loads in the early morning hours, subsequently softens and melts during the course of the day.
Deeply embedded inside the snow cover there are layers of faceted-crystal snow. These are most likely to be trigger-sensitive on the seldom-skied north-facing slopes of southern Valais and Grisons at altitudes between 2400 and 3000 m. Before temperatures plummeted and the snowfall set in this week, the snow cover on north-facing slopes below approximately 2400 m, and on south-facing slopes below approximtely 3000 m, was already thoroughly wet.
Observed weather on Saturday, 22.4.2017
It was sunny, following a night of clear skies.
Fresh snow
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Temperature
At midday at 2000 m, between +4 °C in western regions; and 0 °C in eastern regions; and +6 °C in southern regions.
Wind
Winds at high altitudes were westerly to northwesterly, blowing at moderate-to-strong velocity.
Weather forecast through Sunday, 23.4.2017
In northern and eastern regions, nocturnal skies will be overcast and a small amount of snowfall is anticipated. The snowfall level will descend from 1600 down to 1200 m. During the course of the day, it will become increasingly sunny. In western and southern regions it will be predominantly sunny, following a night of clear skies.
Fresh snow
By Sunday morning, 5 to 10 cm of fresh fallen snow is expected above approximately 1600 m in the central and eastern sectors of the northern flank of the Alps, as well as in northern Grisons. In the Valais and in Ticino, it will remain dry.
Temperature
At midday at 2000 m, between +2 °C in western regions; and -1 °C in eastern regions; and +5 °C in the Valais and in southern regions.
Wind
Winds will be northwesterly, blowing at light-to-moderate strength; in high alpine regions at moderate-to-strong velocity.
Outlook through Tuesday, 25.4.2017
Monday
In southern regions, nocturnal skies will become increasingly overcast. During the morning hours, light snowfall is possible above approximately 1800 m. In northern regions, it will be relatively sunny, following a night of predominantly clear skies. In northern and in eastern regions, the danger of dry-snow avalanches is expected to slowly decrease; the danger of wet-snow avalanches, on the other hand, will increase slightly over the course of the day. In western and southern regions, avalanche danger levels are not expected to change significantly.
Tuesday
In southern regions, snowfall is anticipated above approximately 1600 m. The danger of dry-snow avalanches is expected to increase. In northern regions, only a small amount of snowfall is anticipated and the danger of dry-snow avalanches is not expected to change significantly.