How is an avalanche forecast created?


By meteomorris on 25 November 2018 · 0

The avalanche message is an indispensable tool if you want to go off-piste. In addition to the current avalanche danger in the form of a figure, it contains a range of data, such as:

  • recently fallen and the expected amounts of fresh snow
  • recently and expected wind speeds and wind directions
  • the temperature in the last days and the most current forecast
  • information about the construction of the snow cover
  • a description of the danger zones
  • the load needed to cause a slab avalanche
  • an indication of the type of avalanches that we can expect

But how do they create an avalanche forecast?

A handful of experts is working hard where you can ride safely off-piste (or: where the risks are the lowest) from the beginning till the end of the day. The avalanche services are a 'black box' which just publidh a forecast every day for most people, so a little insight into how an avalanche forecast is created can not hurt, because with that knowledge you can get better insights yourself when you are skiing or snowboarding off-piste. Avalanche services use the following information sources:

1. Observers

Observers spread across the region where the avalanche service is active are exploring their 'backyard' and this information is frequently passed on to the local avalanche service. Avalanche activity is reported and described in detail (angle of inclination, exposition, size, etc.). Furthermore, snow cover characteristics (snow height, amount of new snow, surface hoar, etc.) and weather conditions (clouds, temperature, humidity, wind) are measured.

2. Snow profiles

Snow profiles are regularly dug in fixed places. These are both flat parts and steeper slopes. By digging a snow profile, one gets an idea of the structure of the snow cover and the weak layers that may or may not be present.

3. Automatic weather stations

Automatic weather stations on the mountain report on snow depth, temperatures in and on the snow cover, wind and solar radiation.

4. Weather

Weather is an important factor when it comes to avalanche danger. In addition to the observations, different weather models are used to get at reliable expectations.

5. Reports from the field

Anyone who's on its way in the mountains can report an avalanche. This information is very valuable for the avalanche services, because it allows to fill in the 'gaps' in the monitoring network. In addition to all the aforementioned sources of information, the avalanche service itself also goes out for a check. Every day, profiles are dug and analyzed in interesting areas. The ultimate risk potential is determined by:

  • Stabiliteit van het sneeuwdek en de kans dat een lawine getriggerd kan worden.
  • Grootte, type en aantal lawines.
  • Verspreiding van het aantal lawine gevaarlijke plekken.

  • Stability of the snow cover and the chance that an avalanche can be triggered.
  • Size, type and number of avalanches.
  • Spread of the number of dangerous spots where avalanches can occur.

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