Numerical snowpack model simulation schemes for avalanche prediction in Japan

This paper presents simulation schemes, developed by National Research Institute for Earth Science and Disaster Resilience (NIED), for stability indices and liquid water infiltration that may be applied to a range of numerical snowpack models for avalanche prediction. The schemes were originally developed in the SNOWPACK model, and are introduced for wider application using flow charts, equations, and parameter tables for simulation of the natural stability index, shear strength, and water content. Validation of the stability indices was performed through simulations of eight recent surface avalanche accidents. Even though the simulations did not explicitly consider the weak layer formed by brittle precipitation particles that triggered most of the recent avalanches, they show that avalanche risks are high when stability indices are below a threshold of 2. This result supports previous work and demonstrates the wider applicability of the schemes for providing information on snowpack stability. However, estimation of avalanche risk could be improved through incorporation of information on snow crystal type and associated metamorphism parameterization in numerical snowpack models.