Tropical Storm Nepartak strengthened east of Tokyo on Monday night. At 11:00 p.m. EDT on Monday the center of Tropical Storm Nepartak was located at latitude 35.4°N and longitude 142.3°E which put it about 160 miles (260 km) east of Tokyo, Japan. Nepartak was moving toward the north-northwest at 5 m.p.h. (8 km/h). The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h). The minimum surface pressure was 992 mb.
Tropical Storm Nepartak exhibited a structure a little more like a tropical cyclone on Monday night. Nepartak was embedded in the center of an upper level low. The center of Tropical Storm Nepartak was under the center of the upper level low and the circulation assumed a more circular shape. Bands of showers and thunderstorms were revolving around the center of Nepartak. Winds to tropical storm force extended out 160 miles (260 km) in the eastern side of the circulation. Winds to tropical storm force extended out 100 miles (160 km) in the western side of Nepartak.
Tropical Storm Nepartak will move through an environment capable of supporting a tropical storm during the next 18 hours. Nepartak will move over water where the Sea Surface Temperatures are near 26°C. Since Tropical Storm Nepartak is embedded at the center of an upper level low, the winds are blowing from the same direction at all levels in the troposphere. So, there will be little vertical wind shear. Tropical Storm Nepartak will likely maintain its intensity during the next 18 hours and it could strengthen a little more.
The upper level low and Tropical Storm Nepartak are forecast to drift toward the northwest during the next 24 hours. On its anticipated track the center of Nepartak could make landfall on the northern coast of Honshu near Sendai in about 18 hours. Tropical Storm Nepartak will bring gusty winds and locally heavy rain to parts of northern Honshu. Nepartak already generated waves along the coast of Honshu and some Olympic events at coastal sites were postponed.
Elsewhere, Tropical Storm In-Fa continued to drop heavy rain over parts of eastern China. At 11:00 p.m. EDT on Monday the center of Tropical Storm In-Fa was located at latitude 31.2°N and longitude 119.5°E which put it about 100 miles (160 km) west of Shanghai, China. In-Fa was moving toward the west-northwest at 4 m.p.h. (6 km/h). The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (95 km/h). The minimum surface pressure was 982 mb.