Typhoon Chanthu was spinning over the East China Sea off the central coast of China on September 13, 2021. According to the Joint Typhoon Warning Center (JTWC), at 21:00 UTC (1:00 p.m. EDT) the center of the storm was located about 352 miles (566 km) south-southwest of Kunsan Air Force Base, South Korea. Maximum sustained winds remained near 75 mph (120 km/h), placing it as a weak Category 1 storm on the Saffir-Simpson Hurricane Wind Scale.
The storm is expected to make landfall in or pass very close to the coast of Zhejiang over the next 24 hours. Several media outlets reported that China cancelled flights and trains in Shanghai ahead of the storm’s close approach expected on September 14. After that time, Chanthu is forecast to turn northeastwards and likely weaken before reaching the southern coast of South Korea on September 16-17.
The Moderate Resolution Imaging Spectroradiometer (MODIS) on board NASA’s Aqua satellite acquired a true-color image of Typhoon Chanthu making a close approach to China on September 13. At that time, the large storm had a cloud-filled center and asymmetrical shape. Large convective bands surrounded the center, stretching more than 1,000 km (620 mi) to the northeast, covering parts of Japan with cloud and rain. In contrast, the heavy banding to the southwest of center spanned only about half of that distance.