Due to the influence of the Baiu front, from last weekend to the morning of the 12th, there was a record heavy rain mainly in the Chugoku region and southern Kyushu, causing damage in various places.
According to the Japan Meteorological Agency, in some areas, the amount of rainfall reached four times higher than previously predicted in a series of heavy rains.
During this time of the end of the rainy season, it is difficult to pinpoint where active cumulonimbus clouds occur, and observed rainfall can be much higher than expected.
On the 10th, rain clouds that developed linearly around the southern part of Kyushu struck one after another, and in Kagoshima prefecture, heavy rain continued to fall locally, and houses were flooded mainly in the Sendai River basin such as Satsumasendai City and Satsuma Town. Landslides occurred one after another.
In the vicinity of Satsuma Town, it was estimated that heavy rainfall of about 120 mm had fallen on the early morning of the 10th, and the rainfall for 24 hours was 473 mm, which was the highest since the start of observation.
On the other hand, according to the forecast announced by the Japan Meteorological Agency on the evening of the 9th, the amount of rainfall in the Satsuma district of Kagoshima prefecture including Satsuma town is expected to be 100 mm in 24 hours until 6 pm on the 10th, and it is actually in the same time zone. It was very different from the observed rainfall of 408.5 mm.
One of the reasons for this is that the Japan Meteorological Agency has analyzed that the amount of warm and moist air around the edge of the Pacific High may have continued to flow into southern Kyushu more than expected, and the rainfall may have increased sharply.
In addition, on the 8th of this month, there was a record heavy rainfall in the Chugoku region, and in Tottori prefecture, the 48-hour rainfall in Kurayoshi and Tottori exceeded 300 mm, the highest since we started collecting statistics.
The day before this rain, the Japan Meteorological Agency was most wary of heavy rain in the Sanin region in advance, but in reality, the amount of rainfall exceeded expectations in the Setouchi region on the south side.
Regarding this, the Japan Meteorological Agency says that the amount of warm and moist air flowing from the Kanmon Strait and the vicinity of the Bungo Channel may have exceeded expectations, and cumulonimbus clouds may have occurred one after another.
"End of the rainy season" which is difficult to estimate accurately
On the other hand, during the daytime on the 12th, active rain clouds flowed in again in the Sanin region.
According to radar analysis, it seems that it rained about 100 mm in heavy rain near Unnan City, Shimane Prefecture in the hour until 10 am, and after that, it rained intermittently.
The rainfall for 12 hours until after noon reached 204.5 mm in Sakaiminato City, Tottori Prefecture, and 167 mm in Kashima, Matsue City.
On the morning of the 12th, the Japan Meteorological Agency predicted that the rainfall expected in the Sanin region would be 50 mm for one hour and 100 mm for 24 hours.
From western Japan to northern Japan, it seems that a little strong cold air flowed in during this period, and warm and moist winds were also supplied, causing heavy rain.
At the end of the rainy season, there have been many deviations from expectations, and the Japan Meteorological Agency says, "It is difficult to accurately estimate when, where, and how much rain it will rain."
Heavy rain on the 13th Japan Meteorological Agency "Taking into account sudden changes in the situation"
Atmospheric instability lasts for 13 days and can lead to localized heavy rains.
After that, it is said that rain clouds are likely to develop over a wide area from Tohoku to Kyushu over this weekend, and the rainfall may exceed the expected rainfall.
The Japan Meteorological Agency frequently checks the latest weather information and evacuation information of local governments, taking into consideration that the situation may change suddenly, grasps the dangers in the area before the danger is imminent, prepares for evacuation, etc. We are calling for you to prepare for the event.