Winter and spring ¶
As a general rule, the avalanche bulletin is published daily at 5 pm and consists of the following parts:
- Forecast of the avalanche danger (hazard map and danger description) for the period until 5 pm the next day (in four languages).
- Description of the snowpack and weather in German, valid until 5 pm the next day. The translations (into French, Italian and English) are available by 6 pm at the latest.
In the winter months in particular, the avalanche danger forecast is updated at 8 am (in four languages) when the evening bulletin indicates danger level 3 (considerable) or higher anywhere in Switzerland. If the highest forecast danger level was 2 (moderate), the publication of a morning update depends on the actual situation. Morning bulletins are usually announced in the previous evening’s bulletin.
In principle, an assessment of the avalanche danger can also be issued at other times and without prior notice, but this happens only on rare occasions.
Summer and autumn ¶
From early summer until autumn, avalanche bulletins are published in case of heavy snowfall, and in late autumn at other times as well if the snow cover warrants it. As in this period the volume of on-site data available is less than in mid-winter, these bulletins are less detailed and shorter.
The criteria for the publication of a summer avalanche bulletin are met if the forecast depth of fresh-fallen snow per precipitation occurrence (normally 1 – 3 days) reaches one of the following values:
- 40 cm at 2500 m
- 60 cm at 3000 m
- 80 cm at 3500 m
These values are only intended as a guideline. Whether a bulletin is actually published also depends on the wind, the temperature and the spread and characteristics of the existing snowpack. Furthermore, the snowfall event must affect at least one whole massif; local snow flurries caused for example by individual thunderstorm cells do not count towards this.