JAPAN - Tornadoes are relatively uncommon in Japan, but they have hit the nation with increasing frequency amid global warming.
A tornado ripped through Saitama and Chiba prefectures on Monday, blowing roofs off of buildings and injuring dozens of people. The tornado was spawned by huge cumulonimbus clouds that rapidly developed in the Kanto region on Monday afternoon.
It went on a 10-kilometer rampage, affecting an area from Koshigaya, Saitama Prefecture, and moving northeast to Noda, Chiba Prefecture. According to reports by local governments including those of the two prefectures, more than 600 buildings were damaged, and 64 people had been reported injured as of Tuesday morning.
In Saitama Prefecture, 63 people were injured, seven seriously, while one person was injured slightly in Noda.
In Koshigaya and Matsubushi in Saitama Prefecture, 458 houses and other buildings were damaged, with eight completely destroyed. In Noda, 153 buildings were damaged.
Tsumoru Matsumoto, a forecaster of the Japan Meteorological Agency, said the tornado was triggered by a so-called supercell, a massive column of cumulonimbus clouds with a diameter of more than 10 kilometers.
The agency's Doppler radar, which observes movements of winds in clouds, located in Kashiwa, Chiba Prefecture, about 18 kilometers southeast of the devastated site in Koshigaya, detected a swirl of rising updraft with a diameter of several kilometers-a feature specific to the formation of a supercell.
Cold air at minus 6 C moved over the Kanto region at an altitude of about 6,000 meters Monday afternoon. Meanwhile, near the ground, warm, moist air drifted from the south, causing atmospheric instability and rapidly developing a cumulonimbus cloud.