The center of Typhoon Shanshan passed west of Iwo To on Saturday night.  At 11:00 p.m. EDT on Saturday the center of Typhoon Shanshan was located at latitude 25.4°N and longitude 138.4°E which put the center about 150 miles (240 km) west of Iwo To.  Shanshan was moving toward the northwest at 15 m.p.h. (24 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 974 mb.

Typhoon Shanshan maintained its intensity on Saturday as it moved over the Western North Pacific Ocean west of Iwo To.  Shanshan moved under the eastern side of an upper level low south of Japan.  The upper level low produced southerly winds that blew toward the top of Shanshan’s circulation.  Those winds caused moderate vertical wind shear, and the wind shear prevented intensification of Typhoon Shanshan.

The vertical wind shear also affected the structure of Typhoon Shanshan.  A small circular eye was present at the center of Shanshan’s circulation.  The eye was surrounded by a broken ring of thunderstorms and the strongest winds were occurring in that ring of storms.  Thunderstorms were occurring in bands in the northern side of Typhoon Shanshan.  Bands in the southern part of Shanshan’s circulation consisted primarily of showers and lower clouds.  Storms near the center of Shanshan generated upper level divergence that pumped mass away to the north of the typhoon.  The removal of mass in the upper levels was balanced by the inflow of mass in the lower levels of the atmosphere.  The balance of the outflow and inflow of mass caused the surface pressure to remain steady on Saturday.

Winds to typhoon force extended out 35 miles (55 km) from the center of Typhoon Shanshan.  Winds to tropical storm force extended out 125 miles (200 km) from the center of Shanshan’s circulation.

Typhoon Shanshan will move through an environment that will become more favorable for intensification during the next 24 hours.  Shanshan will move over water where the Sea Surface Temperatures are near 29°C.  It will move farther away from the upper level low south of Japan.  The upper level low will still produce southerly winds that will blow toward the top of Shanshan’s circulation.  However, there will be less vertical wind shear on Sunday.  Typhoon Shanshan is likely to intensify during the next 24 hours.

Typhoon Shanshan will move around the western end of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Shanshan toward the northwest during the next 24 hours.  On its anticipated track, Typhoon Shanshan will move closer to Kyushu and Shikoku.  Shanshan could approach southwestern Japan in 48 hours.  Shanshan could be a strong typhoon when it approaches Japan.