Regional avalanche warning in Norway, a new concept for a large country

Abstract

Norway encompasses 324 000 km2 of land area of which ca. 7 % are mountainsides steeper than 30 degrees. The country extends approximately 1700 km from south to north and features extreme variations in normal precipitation and temperatures from one region to another. A normal winter day can show several seasons in different parts of the country. Yet, the population is scarce and distributed all over the country, connected by long and avalanche prone transport routes through the mountains. This poses a major challenge for avalanche warning. Most weather observations are limited to inhabited areas in lowland terrain and there is no network of neither snow nor avalanche observations. Today, avalanche warnings are only issued for local objects of infrastructure and housing like the Oslo - Bergen railway or Highway 15 connecting east and west Norway. The NGI avalanche warning project in northern Norway which covers 22 000 km2 is a regional approach that also involves local observers. General warnings for large areas at a time are only issued by the Meteorological Office when level high or very high is reached. The Norwegian government has plans to establish a regional avalanche warning service administrated by the Norwegian Water Resources and Energy Directorate. This paper presents a draft concept for such a warning service, technical and administrative challenges and suggestions for their solution based on current technical possibilities and 35 years of NGI avalanche warning experience.