Potential effects of climate change on future snow avalanche activity in western Norway deduced from meteorological data

The formation of snow avalanches is controlled by the complex interaction between terrain characteristics, snowpack and meteorological conditions. Accordingly, snow avalanches exhibit a high sensitivity to climatic variations. This study focuses on the possible effects of climatic variations on snow avalanche activity within one of Norway's most snow avalanche-prone areas. We have statistically analyzed long-term homogenized meteorological data from seven official meteorological stations, three of them with a long-term record of 120 years (1896-2015). In addition, gained results and insights from a four-year (2009-2012) high-resolution snow avalanche monitoring investigation conducted in the same study area are incorporated. Potential effects and overall implications of a changing snow avalanche activity are discussed. Statistical analyses show an increasing trend for both air temperature and precipitation with an accelerated increase for the last 30 years for the core winter period. A tendency for a relationship between a positive North Atlantic Oscillation index and higher precipitation sums during winter could be detected. Magnitude-frequency analyses of monthly precipitation sums for the winter period exhibit an increase of precipitation especially during the last three decades with the tendency that more precipitation can be expected in March and February. An increase of the monthly precipitation sums during the winter period may lead to a generally higher snow avalanche frequency. Due to more frequent periods with air temperatures close or above the freezing point during the winter period, the probability of wet snow avalanches and slush flows will increase.