Typhoon Choi-wan remains on track to slam northern Japan with strong winds, heavy rain and pounding seas late this week.
Choi-wan strengthened into a typhoon on Tuesday, local time, over the open waters of the northern Pacific Ocean.
Additional strengthening will occur through midweek as Choi-wan is guided to the north, bypassing much of mainland Japan.
However, a slight turn to the northwest will put the Kuril Islands directly in the path of Choi-wan with Hokkaido and the Russian island of Sakhalin also facing a blow.
Interaction with cooler water will cause Choi-wan to weaken to a tropical storm prior to reaching the islands. That does not mean that residents should let their guard down.
The center of Choi-wan is expected to cross the Kuril Islands Thursday night, local time, but conditions will begin to deteriorate early Thursday morning.
Into Thursday night, Choi-wan will threaten the Kuril Islands and eastern Hokkaido with wind gusts of 95 kph (60 mph). Locally higher gusts are not out of the question.
"Minor to moderate structural damage and power outages are most likely," stated AccuWeather Meteorologist Anthony Sagliani.
Flash flooding is a significant concern with rainfall on the order of 120 to 200 mm (5 to 8 inches). Coastal flooding will also ensue. Across Hokkaido, Sagliani is most concerned for coastal flooding along the northeast-facing coast, which includes Monbetsu and Shari.
Sapporo and the rest of southwestern Hokkaido will escape the worst, but not all of the storm's wind and rain. "Wind damage should be minor and there should only be an isolated risk for flooding here," stated Sagliani.
As Choi-wan tracks toward the Kuril Islands, gusty winds of 65 kph (40 mph) to as much as 80 kph (50 mph) will develop across northern Honshu, including Sendai, on Thursday and Thursday night. Sporadic tree damage and power outages may occur.
Choi-wan's rain and damaging winds will remain east and north of Tokyo. However, the Pacific waters south and east of Japan will remain dangerously rough for boaters until Choi-wan tracks north of the Kuril Islands on Friday. As Choi-wan tracks northward, seas will also build in the northern Sea of Japan later this week.
Later Thursday into Friday night, the threat of heavy rainfall and locally damaging winds will spread to Sakhalin. Choi-wan will then lose its tropical characteristics this weekend as it spreads some rain and gusty winds to Russia's Kamchatka Peninsula.