Tropical Storm Danas to unleash heavy rain on South Korea, Japan into early next week

By Eric Leister, AccuWeather senior meteorologist

After drenching the Philippines and Taiwan, Tropical Storm Danas will now bring the risk of flooding to South Korea and Japan this weekend.

Danas is expected to slowly move north-northeastward across the East China Sea before crossing the Korean Peninsula and entering the Sea of Japan (East Sea) on Sunday.

Downpours reached southern South Korea on Friday with the heaviest rainfall expected across southern and eastern parts of the country lasting through the day on Saturday.

Heavy rainfall is also expected across western Kyushu and far southwest Honshu on Saturday and Saturday night. These downpours will raise the risk for localized flooding and travel delays.

"The heaviest rain expected across the region could total as high as 150-300 mm (6-12 inches), and will be most likely in southeastern South Korea and far southwestern Japan with an AccuWeather Local StormMax™ of 450 mm (18 inches)," said AccuWeather Senior Meteorologist Dave Houk.

Several hours of heavy, tropical rainfall is likely to oversaturate the ground, increasing the risk for mudslides.

While the primary concern with Danas will be flooding, Danas is expected to remain a tropical storm as it approaches Japan and South Korea. The strongest winds from Danas will remain over the open waters of the East China Sea from Friday into early Saturday before approaching South Korea. However, areas near and east of Danas' track in South Korea could see damaging wind gusts. Wind gusts associated with Danas could reach an AccuWeather Local StormMax™ of 110 km/h (70 mph).

In Japan, the areas most at risk for locally damaging winds and power outages will be western Kyushu and southwestern Honshu as Danas passes near the area from Saturday night into Sunday.

The wind threat is likely to diminish once Danas makes landfall in southern South Korea.

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The exact track of Danas early next week will determine how far north the flooding threat will extend. However, all residents of northern Japan and southeastern Russia should monitor this storm closely as more details become available in the coming days.

By this time, it is possible that Danas will have lost most of its tropical characteristics and much of the threat will have diminished.

Satellite image of Tropical Storm Danas on Friday afternoon, local time. (RAMMB)

Danas began as a tropical depression in the Philippine Sea on Monday morning and quickly strengthened into Tropical Storm Danas east of Luzon by Monday night. In the Philippines, the storm is known locally as Falcon.

Flooding was reported across the Philippines with the heaviest rain falling across northern and western Luzon.

With the track of Danas staying east of the Island, Taiwan avoided the heaviest rainfall and instead was hit with periodic showers and thunderstorms.

Rainfall of 25-75 mm (1-3 inches) was most common with locally higher amounts across the island.

Despite the recently churned-up waters near the Philippines, this area will need to continue to be monitored for further tropical development into the weekend.

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