Snow cover is a major factor influencing the local atmospheric environment. Snow depth in mountainous areas varies significantly owing to the effects of humid air advection and topography. However, snow cover distribution in the mountainous areas of Japan has not yet been quantitatively studied. In this study, in situ meteorological observation data from 2013/14 to 2019/20 on the eastern and western slopes of Mt. Norikura (Northern Japanese Alps) and the surrounding synoptic weather conditions were analyzed. The results showed that snow depth on the eastern slope was greater than that on the western slope. The maximum and minimum snow depths at all sites during the observation period were greater than 229 cm and almost 96 cm, respectively. The variation in annual maximum snow depth was less at the high-elevation site than at the low-elevation site. This is because lower air temperatures at higher elevations make the environment more conducive to stable snowfall and snow accumulation. In addition, variations in snow accumulation with elevation have unique characteristics: 1) the amount of snow accumulation showed a contrast, in that large accumulations in high elevation areas on the east slope and small accumulations in high elevation areas on the west slope are a result of strong westerly winter monsoon wind conditions; and 2) a cyclone along the Japanese south coast, possibly providing easterly air mass advection with a cyclonic circulation towards the slope of Mt. Norikura, supplies much snowfall in the low elevation areas on the east slope. The complex mountainous terrain and atmospheric advection path have created a unique spatiotemporal variation in the snow cover distribution on Mt. Norikura.

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