Combining high spatial resolution snow mapping and meteorological analyses to improve forecasting of destructive avalanches in Longyearbyen, Svalbard

Abstract

Two naturally triggered snow avalanches occurred on 19 December 2015 and 21 February 2017 in the town of Longyearbyen, Svalbard in the Norwegian high-Arctic. These events resulted in two fatalities, numerous injuries, and rendered fourteen residential buildings uninhabitable. Both avalanches occurred on the west-facing slope of the Sukkertoppen Mountain and were preconditioned by similar meteorological conditions. We investigate these two events by combining traditional weather and snowpack analyses with snow distribution data acquired via terrestrial laser scanning (TLS). As limited snow data exists on Svalbard, the TLS-derived snow depth and differential snow depth maps are the primary viable method for the description and analysis of destructive avalanche activity in this location. These TLS-derived surfaces permit detailed assessment of slope-scale snow distribution patterns both prior to and following avalanche activity. We identify strong easterly winds and moderate to heavy snowfall as precursors to destructive avalanche activity on this slope. The results of our investigation help clarify the relationship between winter storm characteristics and avalanche activity in high-Arctic environments and demonstrate the importance of scale-appropriate snow data for avalanche forecasting with increased precision at finer spatial scales. These results have implications for avalanche forecasting in this setting and other data sparse, high-relief Arctic settings where snow distribution patterns are controlled by wind.