Key Facts
• As of August 11, 2 PM, seven cities in Kumamoto issued emergency rain warnings.
• Tamana City recorded 370 mm of rain in six hours, equivalent to two months’ rainfall.
• Rainfall exceeded 550 mm in some areas, surpassing the monthly average of 150–200 mm.
• Heavy rain clouds moved from northern to southern Kyushu on August 11 morning.
• Localized rainfall of 50–60 mm per hour expected in Nagasaki and Fukuoka.
• Urban drainage systems designed for up to 50 mm per hour may face flooding.
• Kumamoto’s Midorikawa River issued a flood risk alert, later downgraded to a cautionary level.
• Rain clouds are expected to spread to Honshu, including Hokuriku, by August 12.
• Post-rain, temperatures in Osaka may reach 35°C from August 14 onward.
• Residents advised to prepare for evacuation and avoid flood-prone areas.
Summary
Kumamoto Prefecture experienced record-breaking rainfall on August 11, with some areas receiving two months’ worth of rain in just six hours. Emergency heavy rain warnings were issued for seven cities, including Tamana and Yatsushiro. Rainfall exceeded 550 mm in certain regions, far surpassing the monthly average. Localized downpours of 50–60 mm per hour were forecasted for Nagasaki and Fukuoka, raising concerns about urban flooding. The Midorikawa River in Kumamoto issued a flood risk alert, later downgraded, but residents were urged to remain cautious. Rain clouds are expected to move toward Honshu by August 12, with Hokuriku likely to be affected. Following the rain, temperatures in Osaka are predicted to rise to 35°C from August 14, marking a return to extreme heat. Authorities recommend preparing for evacuation, avoiding flood-prone areas, and monitoring river conditions remotely for safety.
