Journal cover Journal topic
Natural Hazards and Earth System Sciences An interactive open-access journal of the European Geosciences Union
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
28 Mar 2018
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Natural Hazards and Earth System Sciences (NHESS).
Spatial consistency and bias in avalanche forecasts – a case study in the European Alps
Frank Techel1,2, Elisabetta Ceaglio3, Cécile Coléou4, Christoph Mitterer5, Samuel Morin6, Ross S. Purves2, and Francesca Rastelli7 1WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland
2Department of Geography, University of Zurich Zurich, Switzerland
3Fondazione Montagna sicura, Ufficio neve e valanghe, Regione Autonoma Valle d'Aosta, Italy
4Météo France, Direction des Opérations pour la Prévision, Cellule Montagne Nivologie, Grenoble, France
5Lawinenwarndienst Tirol, Abteilung Zivil- und Katastrophenschutz, Innsbruck, Austria
6Météo France – CNRS, CNRM UMR 3589, Centre d'Études de la Neige, Grenoble, France
7Meteomont Carabinieri, Bormio, Italy
Abstract. In the European Alps, the public is provided with regional avalanche forecasts, issued by about 30 forecast centers throughout the winter, covering a spatially contiguous area. A key element in these forecasts is the communication of avalanche danger according to the five-level, ordinal European avalanche danger scale (EADS). Consistency in the application of the avalanche danger levels by the individual forecast centers is essential to ensure the greatest value for users, particularly those utilizing bulletins issued by different forecast centers. As the quality of avalanche forecasts is difficult to verify, due to the categorical nature of the EADS, we investigated forecast goodness by focusing on consistency and bias exploring real forecast danger levels from four winter seasons (477 forecast days). We qualitatively describe the operational constraints associated with the production and communication of the avalanche bulletins, and we propose a methodology to quantitatively explore spatial consistency and bias. We note that the forecast danger level agreed significantly less often when compared across national and forecast center boundaries (about 60 %), as compared to within forecast center boundaries (about 90 %). Furthermore, several forecast centers showed significant systematic differences towards using more frequently lower (or higher) danger levels than their neighbours. Discrepancies seemed to be greatest when analyzing the proportion of forecasts with danger level 4-High and 5-Very High. Operational constraints in the production and communication of avalanche forecasts, such as the size of warning regions, as well as differences in avalanche winter regimes, and variation in the ways the EADS is interpreted locally may contribute to inconsistencies. All these issues highlight the need to further harmonize the forecast production process and the way avalanche hazard is communicated to increase consistency, and hence value for the user.
Citation: Techel, F., Ceaglio, E., Coléou, C., Mitterer, C., Morin, S., Purves, R. S., and Rastelli, F.: Spatial consistency and bias in avalanche forecasts – a case study in the European Alps, Nat. Hazards Earth Syst. Sci. Discuss.,, in review, 2018.
Frank Techel et al.
Frank Techel et al.
Frank Techel et al.


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