A stationary front over Honshu will bring widespread rain and localized intense thunderstorms across western and northern Japan on Thursday [1, 2].
These contrasting weather patterns pose simultaneous risks of flooding in the north and heat-related illness in the south, complicating regional safety efforts.
The TBS NEWS DIG weather forecast team said the rain and thunderstorms are the result of a stationary front over Honshu combined with moist air and an influx of cold air aloft [1, 2]. The system is expected to impact areas from western Japan to the north, including the Tohoku and Hokuriku regions of north-east Honshu [1, 2].
Forecasters expect the Tōhoku region to see a 24-hour rainfall amount of 10 mm between Wednesday at 18:00 and Thursday at 18:00 [1]. While the north deals with precipitation, western Japan continues to experience a severe heat wave [1, 2].
High pressure and hot, humid air remain concentrated over the western part of the country [1, 2]. This atmospheric stability is driving temperatures upward in the Kyushu region [1, 2].
Specifically, the forecast for Thursday predicts maximum temperatures of 37 °C in Fukuoka, Kurume, Ōita, and Hita [2]. The combination of high heat and humidity increases the risk of heatstroke for residents in these urban, and rural centers [1, 2].
Weather officials said they continue to monitor the stationary front as it interacts with the cold air aloft, which can lead to sudden, heavy downpours in localized areas [1].
“A stationary front over Honshu will bring widespread rain and localized intense thunderstorms.”
The simultaneous occurrence of a stationary front and a high-pressure heat dome illustrates the volatility of late August weather in Japan. While the north faces the risk of flash flooding from localized thunderstorms, the south remains under extreme thermal stress. This split in weather patterns requires coordinated public health responses to address both water-related hazards and heat-related emergencies across different prefectures.
