Weakly bonded old snow in the inneralpine regions
Edition: 19.12.2021, 17:00 / Next update: 20.12.2021, 18:00
Snowpack
In the lower part of the snowpack, particularly on west-facing, north-facing and east-facing slopes above approximately 2200 m, there are weak layers evident. In western Lower Valais and on the northern flank of the Alps these ground-level layers are covered by thick layers of fresher snow so that the likelihood of avalanches being triggered by persons is low. From central Valais over the Ticino as far as Grisons the snowpack layering is least favourable. In those regions there have been isolated medium-sized avalanches triggered by persons during the last few days.
The activity of gliding avalanches is continuing to diminish incrementally. Nevertheless, gliding avalanches continue to be possible on steep grass-covered slopes which have not yet discharged in isolated cases.
During a night of clear skies on Sunday, a melt-freeze crust which is capable of bearing loads will form on the snowpack surface of very steep south-facing slopes. As a consequence of daytime warming and solar radiation, the snowpack surface will become moist on steep south-facing slopes.
Observed weather on Sunday, 19.12.2021
Following a night of clear skies it was sunny in the mountains during the daytime.
Fresh snow
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Temperature
At midday at 2000 m, between +5 °C in the western and the southern regions and +1 °C in the eastern regions.
Wind
Winds in the central and eastern sectors of the Main Alpine Ridge were blowing at moderate to strong velocity from northerly directions; in the other regions winds were light to moderate.
Weather forecast through Monday, 20.12.2021
Following a night of clear skies it will be sunny in the mountains during the daytime.
Fresh snow
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Temperature
At midday at 2000 m, between +2 °C in the western and the southern regions and -1 °C in the eastern regions.
Wind
Winds in the high alpine regions will be blowing at moderate to strong velocity from northerly to northeasterly directions; in the other regions of Switzerland winds will be light to moderate.
Outlook through Wednesday, 22.12.2021
On both days it will be sunny in the mountains.
The danger of dry-snow avalanches is not expected to change significantly. Gliding avalanches continue to be possible in isolated cases.