Item: INTRODUCING SUBLEVELS IN THE SWISS AVALANCHE FORECAST
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Title: INTRODUCING SUBLEVELS IN THE SWISS AVALANCHE FORECAST
Proceedings: International Snow Science Workshop Proceedings 2023, Bend, Oregon
Authors:
- Célia Lucas [ WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland ]
- Simon Grüter [ WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland ]
- Mirjam Eberli [ WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland ]
- Jürg Trachsel [ WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland ]
- Kurt Winkler [ WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland ]
- Frank Techel [ WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland ]
Date: 2023-10-08
Abstract: In public avalanche forecasts, avalanche danger is commonly summarized using one of five ordinal danger levels. This strong simplification of a complex phenomenon inevitably leads to a loss of information. To compensate for this information loss and to ease interpretation of the forecast, the Swiss avalanche warning service introduced sublevels, that indicate whether the forecast danger is in the lower (-), middle (=) or higher (+) range of the danger level. After a 6-year test period, during which it showed that forecasters can reliably assign sublevels to a danger level, the sublevels were published for the first time in the public avalanche forecast in the winter season of 2022/2023. To evaluate the general understanding and the usefulness of the sublevels, and to understand how they influence people's backcountry behavior, we performed a user survey towards the end of the season. The survey with 3403 participants showed that participants perceived the sublevels as generally useful (85%) and that they understood them in the intended manner (94%). Sublevels also had a positive influence on the planning of backcountry tours. Faced with a forecast sublevel (+), almost half of the participants claimed they would change their plans to a less exposed tour than they had before when the same danger level was given but without sublevel information. This self-stated influence of the sublevels on the choice of a backcountry tour was especially important for participants with little or no avalanche training, showing that sublevels seem most useful for less experienced forecast users, who may find it difficult to extract similar information from the forecast text description.
Object ID: ISSW2023_P1.19.pdf
Language of Article: English
Presenter(s): Celia Lucas
Keywords: avalanche forecast, sublevels, warning, communication, user survey
Page Number(s): 240 - 247
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