The weak layer of snow formed by snowfall during cyclone passage generates surface avalanches. This type of avalanche can cause significant problems for humans, traffic, and logistics. Visualizing the level of hazard of these surface avalanches can help minimize the damage they cause. The topographic, snow pit, and meteorological characteristics of two surface avalanches caused by snowfall from a cyclone were analyzed. An algorithm for estimating the risk of surface avalanches caused by snowfall in a typical winter monsoon and during a cyclone was developed based on the analysis results. By incorporating the results of our previous study into the algorithm for estimating the risk of surface avalanches due to snowfall from a cyclone, we were able to improve the avalanche potential estimation algorithm such that it can cover surface avalanches generated by snowfall following the typical winter monsoon pattern after a cyclone has passed. In the three cases we verified, a warning was issued because the threshold of danger was exceeded before the surface avalanche occurred.

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