Tropical Storm Nari developed over the Western North Pacific Ocean south of Japan on Saturday.  At 5:00 p.m. EDT on Saturday the center of Tropical Storm Nari was located at latitude 25.8°N and longitude 142.4°E which put the center about 715 miles (1150 km) south-southeast of Tokyo, Japan.  Nari was moving toward the east-northeast at 9 m.p.h. (15 km/h).  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 998 mb.

A low pressure system over the Western North Pacific Ocean strengthened on Saturday and the Japan Meteorological Agency designated the system as Tropical Storm Nari.

More thunderstorms formed near the center of Tropical Storm Nari on Saturday.  More thunderstorms also developed in bands in the eastern side of Nari’s circulation.  Bands in the western side of Tropical Storm Nari consisted primarily of showers and lower clouds.  Storms near the center of Nari generated upper level divergence that pumped mass away to the south of the tropical storm. The removal of mass caused the surface pressure to decrease.

The distribution of winds speeds in Tropical Storm Nari was asymmetrical.  Winds to tropical storm force extended out 110 miles (185 km) in the eastern side of Nari’s circulation.  The winds in the western side of Tropical Storm Nari were blowing at less than tropical storm force.

Tropical Storm Nari will move through an environment that will be mostly favorable for intensification during the next 24 hours.  Nari will move over water where where the Sea Surface Temperatures are near 29°C.  It will move under the southeastern part of an upper level low south of Japan.  The upper level low will produce westerly winds that will blow toward the top of Nari’s circulation,  Those winds will cause moderate vertical wind shear.  The vertical wind shear will inhibit intensification, but the shear will not be enough to prevent intensification.  Tropical Storm Nari will intensify during the next 24 hours.

Tropical Storm Nari will move around the western side of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Nari toward the north during the next 24 hours.  On its anticipated track, Tropical Storm Nari will move toward eastern Japan.  Nari could approach eastern Honshu in 36 hours.