Tropical low to unleash downpours, hamper recovery from Japan earthquake

By Courtney Spamer, AccuWeather meteorologist

By Adam Douty, AccuWeather senior meteorologist

September 09, 2018, 10:59:17 AM EDT

After former Typhoon Jebi and several typhoons and tropical storms during the month of August, Japan will again be bracing for tropical rains.

A tropical depression that traveled through the Philippine Sea for the first week of September has since dissipated near the Ryukyu Islands of southern Japan.

Despite weakening, the tropical moisture lingering from this system will combine with a front moving through the Sea of Japan bringing another flooding threat.

“A plume of moisture along the front will dump bouts of heavy rain across Japan through Monday,” said AccuWeather Senior Meteorologist Dave Houk.

Much of the country, from the island of Kyushu to eastern Hokkaido, will be at risk for the heavy, tropically enhanced rain, with widespread amounts of 75-150 mm (3-6 inches). 

“The hardest-hit areas, likely in southwestern and western Honshu, could get up to 200 mm (around 8 inches) of rain through Monday, with an AccuWeather Local StormMax™ of 300 mm (12 inches) of rain,” Houk added.

From Friday night and into Saturday, parts of Shikoku and western Honshu already received 100-150 mm (4-6 inches) of rain. This heavy rain is expected to spread eastward into central Honshu through Monday.

Downpours can cause localized flooding and travel disruption.

This wet weather alone could cause flooding issues for Japan, but in the wake of Typhoon Jebi, flooding will be even more exaggerated. Even 100 mm (4 inches) of rain can be the tipping point that causes a mudslide.

Any rain, no matter how heavy, will hinder cleanup efforts following the former typhoon.

RELATED: 
AccuWeather Japan Homepage 
AccuWeather radar in Japan 
Japan begins cleanup after Typhoon Jebi

The increased chance of mudslides may also be the case for places across southern Hokkaido, where residences are still cleaning up from the recent 6.7 magnitude earthquake. The deadly quake shook the island early on Thursday morning, local time, damaging structures and burying homes in mud.

After some dry weather on Saturday, rain returned to southern and eastern Hokkaido on Saturday night and is expected to continue on and off through Monday.