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Abstract:
Avalanche formation depends on terrain characteristics, snowpack, and meteorological conditions. Of these, meteorological parameters, such as temperature, precipitation, and wind, strongly influence the possibility of a catastrophe in an avalanche-prone area. One-fourth of Norway´s public roads are exposed to the risk of avalanches; hence, the Norwegian Meteorological Institute (MET Norway) produces daily warnings on a scale of 1-5, 5 being the maximum danger level of risk of avalanche activity. The warnings are restricted to the winter period, i.e. December, January, February, March, and April. In this study, we identify the regions in Norway with high avalanche warnings (warning >= 4, named the `avalanche day´) based on the MET warnings. Four regions in Norway, namely Ofoten, Salten, Svartisen, and Hegeland, observed maximum avalanches (>= 35) between Dec 2017 and April 2022.The two conditions that drive the instability of the snowpack are (i) loose snow and (ii) slab avalanches. In particular, wet snow instances and persistent weak layers in the snowpack of slab avalanches are responsible for most avalanches in these four regions. To understand the impact of meteorological variables on these avalanches, we utilise the long-term observational gridded datasets (1 km resolution) from MET Norway. Over the last five years (Dec 2017- April 2022), during the winter months, the daily mean temperature analysis shows an increase three days before the `avalanche day´, but the accumulated precipitation increases by 12.5% a day before the event. Future work entails analysing long-term climate data for avalanche monitoring and prediction studies.
