In the south, skies will be mostly overcast and snow will fall down to low altitudes. Precipitation will accumulate following a southeasterly course, especially on the Main Alpine Ridge in Upper Valais, where around 20 to 40 cm of snow will fall by Friday, with up to 20 cm falling on the rest of the southern flank of the Alps. In the north, conditions will be mostly sunny in the mountains. There will be a strong foehn wind but there is little transportable snow. Avalanche risk will increase in regions with fresh snow, significantly so on the Main Alpine Ridge in Upper Valais.
"}], "validTime": {"endTime": "2025-12-24T16:00:00Z", "startTime": "2025-12-23T16:00:00Z"}, "bulletinID": "a8b84cce-14c9-49de-9078-78b641887417", "customData": {"CH": {"aggregation": [{"category": "dry", "problemTypes": ["persistent_weak_layers"], "validTimePeriod": "all_day"}]}}, "nextUpdate": "2025-12-24T16:00:00Z", "unscheduled": false, "dangerRatings": [{"mainValue": "moderate", "customData": {"CH": {"subdivision": "minus"}}, "validTimePeriod": "all_day"}], "weatherReview": {"comment": "Conditions were mostly overcast with high cloud. There was some light snowfall in some southern regions.
A few centimetres fell locally on the Main Alpine Ridge in Valais and in Valle Maggia.
At midday at 2000 m, between +4\u00b0C in the north and 0\u00b0C in the south
Southerly:
Conditions will remain sunny in the morning but low stratus cloud cover will gather from the north in Alpine valleys up to higher than 2000 m. A little snow may fall. Over the course of the day, clouds will gather in the south and snow will start to fall. The snowfall level will be at low altitude.
A few centimetres on the northern edge of the Alps and on the southern flank of the Alps
At midday at 2000 m, between -7\u00b0C in the north and -3\u00b0C in the south
There is appreciably less snow than usual at this time of year in most regions and snow conditions for ski touring are very poor in many places. Only in northern Lower Valais are snow depths approaching average. On southern slopes and in general below 2400 m, the snowpack has mostly frozen solid.
On the Main Alpine Ridge in Valais and in western Ticino, the small volumes of fresh snow which have fallen in the last few days are lying on a thin but weak old snowpack of faceted crystals. Avalanches may be triggered in these regions. In the inneralpine regions of Valais, on the southern flank of the Alps and throughout Grisons, there are sometimes pronounced weak layers of faceted crystals or surface hoar in the snowpack, especially on northern and eastern slopes above approximately 2400 m. However, only very isolated avalanches have been triggered in these layers. Further north, the structure of the snowpack is more favourable.
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