Former Tropical Storm Shanshan strengthened into a typhoon southeast of Japan on Saturday. At 5:00 a.m. EDT on Saturday the center of Typhoon Shanshan was located at latitude 21.2°N and longitude 148.5°E which put it about 245 miles (395 km) northeast of Agrihan. Shashan was moving toward the north-northwest at 10 m.p.h. (16 km/h). The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were wind gusts to 90 m.p.h. (145 km/h). The minimum surface pressure was 975 mb.
A primary rainband wrapped around the center of circulation and an eye was developing at the center of Typhoon Shanshan. The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms. Several bands of showers and thunderstorms were revolving around the core of Shanshan. The strongest rainbands were south and east of the center of circulation. Bands north and west of the center consisted primarily of showers and lower clouds. Storms around the core were generating upper level divergence which was pumping mass away from the typhoon. Shanshan has a large circulation. Winds to tropical storm force extend out about 190 miles (305 km) from the center of circulation.
Typhoon Shanshan will move through an environment favorable for intensification during the next 24 to 48 hours. Shanshan will move over water where the Sea Surface Temperature is near 28°C. It will move through a region where the upper level winds are weak and there will be little vertical wind shear. Typhoon Shanshan will intensify and it could strengthen into the equivalent of a major hurricane.
Typhoon Shanshan will move around the western portion of a subtropical ridge over the Western North Pacific Ocean. The ridge will steer Shanshan in a north-northwesterly direction. On its anticipated track the center of Typhoon Shanshan will pass east of Iwo To in 24 to 36 hours. Shanshan could be just southeast of Honshu in about four days.