Characterizing snow instability with avalanche problem types derived from snow cover simulations

Abstract

Snow cover models support avalanche forecasting. However, despite much development to derive snow instability from snow cover model output, snow cover models presently do not provide information on avalanche problem types – an essential element to describe avalanche danger. We present an approach to detect, track and assess weak layers in snow cover model output data and assess the related avalanche problem types. We classify different avalanche situations into new snow, wind slab, persistent weak layer and wet-snow problems for either natural or artificial avalanche release. We demonstrate the applicability of this approach with both SNOWPACK and Crocus model output for several winter seasons at Weissfluhjoch, Switzerland, and two sites in Western Canada. At Weissfluhjoch, simulation results from both models coincided reasonably well with avalanche activity recorded with a seismic avalanche detection system. Over a 16-year period both models produced similar frequencies of avalanche problems. At the two Canadian sites frequencies of simulated avalanche problem types agreed fairly well with the observed frequencies. The results provide confidence that avalanche problem types can be simulated in different snow climates and that changes due to climate change can be studied. Moreover, the approach to assess avalanche problem types holds potential to support operational avalanche forecasting.