Nat. Hazards Earth Syst. Sci. Discuss., https://doi.org/10.5194/nhess-2018-74 Manuscript under review for journal Nat. Hazards Earth Syst. Sci. Discussion started: 28 March 2018 c Author(s) 2018. CC BY 4.0 License. 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 Correspondence to: Frank Techel (
[email protected]) 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 ap- 5 plication 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 dif- ficult 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).