Nat. Hazards Earth Syst. Sci., 18, 2697–2716, 2018 https://doi.org/10.5194/nhess-18-2697-2018 © Author(s) 2018. This work is distributed under the Creative Commons Attribution 4.0 License. Spatial consistency and bias in avalanche forecasts – a case study in the European Alps Frank Techel1,2, Christoph Mitterer5, Elisabetta Ceaglio3, Cécile Coléou4, Samuel Morin6,8, Francesca Rastelli7, and Ross S. Purves2 1WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland 2Department of Geography, University of Zürich, 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 8Université Grenoble Alpes, Université de Toulouse, Toulouse, France Correspondence: Frank Techel (
[email protected]) Received: 16 March 2018 – Discussion started: 28 March 2018 Revised: 6 September 2018 – Accepted: 5 October 2018 – Published: 23 October 2018 Abstract. In the European Alps, the public is provided with danger level 4 – high and 5 – very high. The size of the warn- regional avalanche forecasts, issued by about 30 forecast cen- ing regions, the smallest geographically clearly specified ar- ters throughout the winter, covering a spatially contiguous eas underlying the forecast products, differed considerably area. A key element in these forecasts is the communication between forecast centers. Region size also had a significant of avalanche danger according to the five-level, ordinal Eu- impact on all summary statistics and is a key parameter in- ropean Avalanche Danger Scale (EADS).