menu

jump links

selected

Content

Danger levels snow

Snow is the most common form of solid precipitation and consists of many very small ice crystals. These form at temperatures below -4 °C, and fall to earth, as long as their falling speed and the temperature and humidity below the clouds do not allow the crystals to melt or evaporate.

Danger level 5 (very severe danger)
Effects
  • Road and air traffic is brought to a standstill
  • Massive disruption to rail transport
  • Falling branches or trees as a result of the weight of their snowload
  • Heavy snowload on roofs
  • Breakdown of electricity supply and telephone communications network
Behaviour Information on recommended action can be found here:  What to do during snowfall
Description of measurement and prognostic values
  • Heavy/intensive snowfall in lowland areas of German-speaking Switzerland: >50 cm/24 h
  • Heavy/intensive snowfall in lowlands of Western Switzerland and south of the Alps: >50 cm/24 h
  • Heavy/intensive snowfall in the mountains: >100 cm/24 h, >140 cm/48 h, >180 cm/72 h
Danger level 4 (severe danger)
Effects
  • Impassable sections of road;
  • Disruption to air and rail travel;
  • Falling branches or trees as a result of the weight of their snowload;
  • Interruption of electricity supply and/or telephone network, particularly in regions that are not easily accessible;
  • Heavy snowload on roofs.
Behaviour Information on recommended action can be found here:  What to do during snowfall
Description of measurement and prognostic values
  • Heavy/intensive snowfall in lowland areas of German-speaking Switzerland: 30-50 cm/24 h
  • Heavy/intensive snowfall in lowlands of Western Switzerland and south of the Alps: 30-50 cm/24 h
  • Heavy/intensive snowfall in the mountains: 70-100 cm/24 h, 100-140 cm/48 h, 140-180 cm/72 h

 

Danger level 3 (significant danger)
Effects
  • Worsening of road condition
  • Disruption to air and rail travel
  • Branches breaking due to snowload
Behaviour Information on recommended action can be found here:  What to do during snowfall
Description of measurement and prognostic values
  • Heavy/intensive snowfall in lowland areas of German-speaking Switzerland: 15-30 cm/24 h
  • Heavy/intensive snowfall in lowlands of Western Switzerland and south of the Alps: 10-30 cm/24 h
  • Heavy/intensive snowfall in the mountains: 40-70 cm/24 h, 70-100 cm/48 h, 100-140 cm/72 h
Danger level 2 (moderate danger)
Effects
  • Slippery conditions due to snow-covered roads
Behaviour Information on recommended action can be found here:  What to do during snowfall
Description of measurement and prognostic values
  • Snowfall (Western Switzerland, south of the Alps): Lowland areas: 5-10 cm (in max. 24 h), Mountains: 20-40 cm (in max. 24 h)
  • Snowfall (German-speaking Switzerland, Canton Fribourg): Lowlands: 5-15 cm (in max. 24 h), Mountains: 20-40 cm (in max. 24 h)

Notes:

The snowfall warnings are primarily issued for widespread precipitation.

*The warning threshold values in category 3 for lowland areas differ according to region, with warnings being issued from 10 cm for Western and Southern Switzerland, and from 15 cm for German-speaking Switzerland.

Useful links:

Kontextspalte