Two storms, Typhoon 7 and Typhoon 8, are expected to strike the Japanese archipelago through Saturday, June 27, 2024 [1].
The simultaneous arrival of these systems creates a high risk of severe flooding and landslides because the typhoons are interacting with a seasonal rain front to increase precipitation [2].
Forecasters predict the heaviest rainfall will hit the Tokai region, with expected totals reaching 350 mm [1]. Other areas face significant threats as well, with 200 mm of rain projected for the Kanto, Koshin, and Kinki regions [1]. Shikoku is expected to see 180 mm [1], while southern Kyushu may receive 120 mm [1].
The Japan Meteorological Agency said Typhoon 8 is forecast to develop maximum instantaneous wind speeds of 35 m/s [3]. The agency said the storms could potentially make landfall in the Tokai and Kanto regions.
Early impacts have already been reported. In the Matsubara Junction, parts of the inbound lane became impassable starting shortly after 7 a.m. on June 26 due to road flooding [4].
Authorities are urging residents across Japan, including Northern Japan, to remain vigilant against rising river levels and soil disasters as the systems move north [1].
“Tokai is expected to see up to 350 mm of rain.”
The convergence of two tropical cyclones with an existing rain front significantly amplifies the volume of precipitation beyond what a single storm would produce. This 'double typhoon' scenario increases the likelihood of saturated soil, which elevates the risk of landslides and flash floods in mountainous regions and urban centers across central and southern Japan.
