Remarkable snowfall measurements were recorded during this uncommon event. Not only were the snow totals impressive, but the speed at which it fell also caught the attention of meteorologists. On Monday, a weather station in Obihiro, Hokkaido, reported a staggering 47.24 inches of snowfall within just 12 hours. This amount more than doubled the station’s previous 12-hour snowfall record spanning 26 years of data, according to the JMA. Additionally, five other locations in Hokkaido also set new 12-hour snowfall records since the mid-1980s. Weather historian Christopher Burt highlighted that this event ranked among the most intense 12-hour snowfalls ever recorded globally. Comparatively, only Thompson Pass in Alaska and Montague Township in New York have experienced similar snowfall rates in North America.
The occurrence of such a substantial snowfall within a short duration raises the question: how can an area accumulate nearly as much snow in 12 hours as Denver, Colorado, typically receives in an entire year? The rapid snowfall rate observed on Monday was attributed to a swiftly intensifying low-pressure system over the northern Sea of Japan, where moist air was forced upward over lingering cold air above Hokkaido. This setup created conditions conducive to what is known as “sea-effect snow,” an atmospheric phenomenon resembling lake-effect snow in the Great Lakes region. The bitter cold air from Siberia and Manchuria, with temperatures well below freezing, interacted with the relatively warmer Sea of Japan waters, generating heavy snow bands that were carried inland by westerly winds and lifted by the Japanese Alps. Consequently, areas east and south of the Japanese Alps typically receive less snow due to the moisture being depleted over the mountains.
Japan’s proximity to frigid Siberian air makes its sea-effect snow zones among the most prolific globally. For instance, Sukayu in northern Honshu receives an astonishing average of 694.5 inches of snowfall annually. The region around Japan’s Mt. Ibuki holds the record for the highest known 24-hour snowfall and snow depth, with 90.6 inches of snowfall and 465.4 inches of accumulated snow on the ground reported on Feb. 14, 1927. The frequent heavy snowfall necessitates unique adaptations, such as homes with extended eaves to prevent snow buildup and the use of underground sprinklers to melt accumulated snow off roofs.
Jonathan Erdman, a senior meteorologist at weather.com, has been extensively covering national and international weather events.
Al Weather has been a weather enthusiast since 1996, with a particular interest in extreme and peculiar weather phenomena. You can connect with him on Bluesky, X (formerly Twitter), and Facebook.
