Former Typhoon Guchol weakened to a tropical storm over the Western North Pacific Ocean south of Japan on Sunday. At 5:00 p.m. EDT on Sunday the center of Tropical Storm Guchol was located at latitude 27.4°N and longitude 136.0°E which put it about 650 miles (1050 km) south-southwest of Tokyo, Japan. Guchol was moving toward the northeast at 20 m.p.h. (32 km/h). The maximum sustained wind speed was 70 m.p.h. (110 km/h) and there were wind gusts to 85 m.p.h. (135 km/h). The minimum surface pressure was 984 mb.

Former Typhoon Guchol weakened to a tropical storm on Sunday when it moved into a less favorable environment. An upper level trough west of Japan produced westerly winds that blew toward the top of Guchol’s circulation. Those winds caused moderate vertical wind shear and the wind shear caused Guchol to weaken. There was no longer an eye at the center of Guchol’s circulation. Thunderstorms were still occurring in bands in the northern and eastern parts of Tropical Storm Guchol. Bands in the western and southern parts of the circulation consisted primarily of showers and lower clouds. Storms near the center of Guchol generated upper level divergence that pumped mass away to the northeast of the tropical storm. Winds to tropical storm force extended out 175 miles (280 km) from the center of circulation.

Tropical Storm Guchol will move through an environment that will be unfavorable for intensification during the next 36 hours. Guchol will move over water where the Sea Surface Temperatures are near 26˚C. The upper level trough west of Japan will continue to produce westerly winds that will blow toward the top of Guchol’s circulation. Those winds will cause moderate vertical wind shear. Tropical Storm Guchol will continue to weaken as it moves over cooler water and is affected by moderate vertical wind shear. Guchol could make a transition to an extratropical cyclone early next week.

The upper level trough west of Japan will steer Tropical Storm Guchol toward the northeast during the next 36 hours. On its anticipated track Tropical Storm Guchol will pass south of Tokyo in less than 24 hours.