Sunday’s devastating tornadoes in Ibaraki and Tochigi prefectures were caused by a rare situation attributed in part to a winter that went on for some weeks longer than normal, and a recent sharp rise in surface temperatures, experts said Monday.
One person died and several were injured in the twisters.
“Tornadoes rarely occur in this season,” said Yasushi Fujiyoshi, professor at Hokkaido University. “It is rare in the first place for cold air to form in the troposphere in May.”
Fujiyoshi said such frigid air is more a feature of the fall and the extended period of freezing weather earlier this year helped create the atmospheric conditions conducive to tornado-formation.
He also warned there is a possibility that massive, unstable cumulonimbus cells, the main source of thunder, hail and tornadoes, will be more common this year, but added this does not necessarily spell more tornadoes, because there are many other conditions affecting wind movements that help spawn twisters.
Experts noted that tornadoes form during unstable atmospheric conditions when thunderclouds form quickly.
On Sunday, with the air at minus 21 degrees at an altitude of 5,500 meters, a warm air mass moved in over an area stretching from the Tohoku to the Tokai regions. This created conditions for thunderclouds to form, bringing with them heavy rain and hail.
Unlike in the U.S., tornadoes in Japan are more common between August and October, during the main typhoon season, said Takeo Tanaka, head of the weather information office at the Meteorological Agency. But he added that the mechanism of how and why tornados form has yet to be pinpointed.
Whatever theories meteorologists may have, residents living in the affected areas in Tsukuba, Ibaraki Prefecture, and Moka, Tochigi Prefecture, face tough challenges ahead.
On Monday morning, they were busy clearing debris left in the storm’s aftermath, including flipped cars and roofless and devastated structures.
Yoshio Asano, 51, who lives with his 81-year-old mother, said they spent Sunday night in a room that survived the twister. Their house was partially damaged.
“We felt scared because we were left without electricity,” he said. “But we were prepared. We had emergency flashlights and batteries because of the March 11 earthquake last year.”
Even so, Asano said he is at a loss when he thinks about what to do, where to start, and what’s going to be waiting for him as he tries to rebuild his life.
For him and others left to pick up the pieces, there is the reality that the power of Mother Nature if a force to be reckoned with.
“A blame game won’t get us anywhere,” Yasushi Izumi, a 38-year-old office worker who lives in the area, said as he cleared shattered glass and other debris at his home.
Information from Kyodo added