Severe flooding and mudslides in the Yamaguchi and Shimane Prefectures of Japan over the last few days were the result of record levels of rainfall. One person has been reported killed in the flooding and a number of others are still missing. The rainfall was so heavy, the Meteorological Agency in Japan described it as “unprecedented”. Estimate say that the region saw half of the average monthly rainfall in just a few hours on Sunday 28th July.
The heavy rain caused the River Abu-gawa burst its banks bringing floods to the city of Hagi, Yamaguchi Prefecture, which stands on the river delta. Full scale search and rescue operations began on Monday. The victim was an elderly woman found under a collapsed house in Hagi. A further 10 people were injured in the tragedy and another 480 people were rescued by helicopter from the flooded area.
The floods also affected the transport network, with train lines and roads blocked by landslides or flood water, including national routes.
Around 5,000 people are believed to be affected by the floods, many of whom have been told to evacuate their homes as storms were expected to continue, bringing the risk of further floods and landslides.
So why all the rain?
According to Japan News, the heavy rainfall was due to:
…an atmospheric depression caused by the westerlies that snake their way south near Japan. The system pushes cold air from the north upward where it meets warm, humid air at the edge of the high-pressure system in the Pacific Ocean.
According to the meteorological agency, downpours tend to be short in summer because the Pacific high usually covers all of Japan. However, an agency official said fronts are forming near Japan more frequently this year because the westerlies have developed a pressure pattern similar to that seen in the rainy season.
There is also low pressure above the Sea of Japan, which moves slowly due to the cold air, thus causing the front to linger in the Chugoku region. As the elevated air was pushed to east by the westerlies, the updraft continued, causing heavy rainfall for hours.
The agency forecasts an unstable atmosphere in eastern Japan, as the front is expected to stretch to east.
Sources:
Disaster Charter; Photo Credit and Source: Japan News
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