Automated Avalanche Hazard Indication for Southeast Alaska

Abstract. Snow avalanches represent a significant yet poorly characterized natural hazard in Alaska, where risk assessment is limited by extreme data scarcity, rapidly changing climate conditions, and land-use policies that often inadequately account for environmental uncertainty. We address these challenges in Southeast Alaska by developing the region’s first systematic, large-scale avalanche hazard indication maps to support public safety, infrastructure planning, and land-use decision-making. To overcome sparse observational records, we developed a hybrid modeling framework that integrates downscaled reanalysis for historical baselines (1981–2010) with dynamically downscaled climate projections for mid-century conditions (2031–2060). More than 3.5 million avalanche simulations were performed using RAMMS::LSHIM driven by downscaled snow inputs. Forest landcover masks were incorporated to represent both suppression of avalanche release and vegetation-induced braking during runout, recognizing that these simplified effects remain sensitive to landcover classification accuracy and assumed release-area configurations. The resulting maps reveal a heterogeneous response of avalanche hazards to climate change. At lower elevations, hazard extents generally decrease as warming temperatures shift precipitation from snow to rain. In contrast, select high-elevation areas of northern Southeast Alaska are projected to experience increased runout, where persistently low temperatures, combined with enhanced atmospheric moisture, lead to greater maximum snowfall. Collectively, these results provide the first region-wide, climate-informed assessment of avalanche susceptibility in Southeast Alaska, establishing a critical foundation for hazard adaptation, infrastructure resilience, and future mitigation strategies across Alaska’s sub-Arctic landscapes.