Japan is famous for its abundance and consistency of snowfall, or "Japow", in the middle of winter, and has become a popular global destination for powder-thirsty skiers and snowboarders.
So why exactly does Japan receive so much snow in the winter, compared to other ski regions?
Asian Winter Monsoon
The driver of Japan's snow is the Asian Winter Monsoon, which is characterized by a cold, northwesterly flow from Siberia over the Sea of Japan. This produces copious sea-effect snowfall that inundates western Honshu and Hokkaido.
During the winter, cold dry air masses form over Siberia and sweep eastward. These air masses pick up moisture over the relatively warmer Sea of Japan.
Once the moist air hits Japan’s mountainous west coast, orographic uplift forces heavy precipitation that results in abundant, fluffy powder.
Japan Sea Convergence Zone
Honshu, compared to the northern Island of Hokkaido, is more prone to bigger storms in part due to the Japan Sea Convergence Zone.
The Japan Sea Convergence Zone is an atmospheric river-like cloud zone that forms when Siberian cold air flows over the topography of Korea and then over the warm Japan Sea.
This leads to exceptionally heavy snowfalls on Honshu, oftentimes at resorts in the Nagano and Niigata prefectures.