While Dujuan is no longer a powerful typhoon, it will still target mainland Japan and the Korean Peninsula with drenching rain and gusty winds into Thursday night.
Dujuan is currently a tropical rainstorm after weakening over eastern China in the wake of its second landfall in the Fujian Province on Tuesday, local time.
Periods of rain will persist across the Chinese provinces of Anhui and Jiangsu into the start of Thursday as Dujuan tracks northeastward. Rainfall will generally be on the order of 25 to 50 mm (1 to 2 inches), keeping flooding issues on an isolated level.
After Dujuan departs China, it will combine with a non-tropical storm system tracking through northeastern China.
"This merger will create a strong non-tropical system that will bring potentially flooding rain and gusty winds to the Korean Peninsula and Japan," stated AccuWeather Meteorologist Eric Leister.
This adverse weather will spread in a west-to-east fashion across the area into Thursday evening, eventually also targeting far southeastern Russia later Thursday into Thursday night.
The heaviest rain, and greatest potential for localized flooding, will fall from South Korea to northern Japan and far southeastern Russia. Even where flooding does not ensue, any downpours will heighten the risk of vehicles hydroplaning when traveling at highway speeds.
"Due to the fast movement of this storm, total rainfall will generally average 25 to 75 mm (1 to 3 inches) of rain," continued Leister. "The rain will fall quickly, with most areas experiencing only six to 12 hours of rain."
A separate area of similar rain totals may unfold in the higher terrain of China's eastern Liaoning and southwestern Jilin provinces.
Gusty winds will also increase as Dujuan and the non-tropical system combine, meaning stronger winds are expected in and around the Sea of Japan than points to the west.
"Wind gusts will generally be on the order of 65 to 80 kph (40 to 50 mph) around the northern East China Sea and 80 to 95 kph (50 to 60 mph) around the Sea of Japan and Japan's eastern coast," stated AccuWeather Meteorologist Adam Douty.
There can be locally higher winds on the coast of Hokkaido and the coasts of eastern Honshu, while gusts to 65 to 80 kph (40 to 50 mph) are also expected along the southern coast of Japan from western Honshu to Kyushu.
"No widespread damage is expected from the winds; however, the gusty winds, combined with heavy rain can result in travel disruptions across the region and sporadic power outages," added Leister.
Residents with outdoor activities should prepare for possible postponements or alternate plans. Loose lawn items should be secured or moved indoors as the gusty winds can easily toss these items around.
Cities likely to experience the gusts of 65 to 80 kph (40 to 50 mph) include Jeju and Busan, South Korea; and Nagasaki, Fukuoka, Hiroshima, Kochi and Hamamatsu, Japan. Gusts will be on the lower end of this range in Seoul, South Korea, and Shanghai, China.
Sapporo, Sendai and Akita, Japan, are at risk for the gusts of 80 to 95 kph (50 to 60 mph).
"Around Tokyo, the greatest opportunity for the southwesterly winds to gust to 95 kph (60 mph) will be around Tokyo Bay with gusts closer to 65 kph (40 mph) farther inland," said Douty.
Calmer and drier conditions will return to southern Japan and the southern East China Sea on Friday, while a cold front drops southward and leads to showers and persistent gusty winds from the northern Korean Peninsula to northern Japan.
Snow may even fall in the highest mountains along the border of North Korea and China.