Tropical Storm Ampil


Severe Tropical Storm Ampil, known in the Philippines as Severe Tropical Storm Inday, was a tropical cyclone that caused moderate damage in the Ryukyu Islands and East China in late July 2018. The tenth named storm of the annual typhoon season, Ampil developed into a tropical depression east of Luzon on July 17. The storm gradually strengthened in the following days, and achieved its peak intensity late on July 19. Maintaining peak strength, Ampil passed through the Okinawa Island late on July 20. After that, Ampil began to slowly weaken, as environmental conditions became less favourable. Ampil made landfall in Shanghai on July 22, before becoming extratropical two days later.

Meteorological history

On July 17, the Japan Meteorological Agency began to monitor a tropical depression over the Philippine Sea. The Joint Typhoon Warning Center designated it as 12W later that day. The depression initially moved westwards, and turned to east-northeast on the next day, carried by monsoon westerlies. The system gradually organised under low wind shear, warm sea surface temperature of, and good equatorward outflow. On the same day, the JMA said that the system has strengthened to a tropical storm, and received the international name Ampil. The JTWC followed suit later. At that time, Ampil had an asymmetrical structure. Its deep convection and the banding features were located south of the center, and the low-level circulation center was partially exposed. Late on July 19, Ampil began to turn northward, and then northwestward, under the influence of a subtropical ridge to the south. The storm also slightly strengthened under marginally favourable environment. The LLCC was wrapped by curved convection. Because of this, the JMA upgraded it to a severe tropical storm, and Ampil simultaneously achieved its peak intensity, with maximum sustained winds of 95 km/h and a minimum barometric pressure of 985 hPa. Late on July 20, Ampil passed directly over the Okinawa Island, near Nago, while maintaining its peak strength.
After passing Okinawa Island, Ampil began to slowly weaken, due to limited ocean heat content, while continued to move northwestward. Its LLCC became partially exposed again, and most of the convection were located at the northern part of Ampil. The JMA reported that Ampil had weakened to a tropical storm early on July 22. At 12:30 p.m. CST, Ampil made landfall in Chongming Island, Shanghai. Upon doing so, Ampil became the eleventh tropical cyclone that made landfall in Shanghai, and the third tropical cyclone that directly struck Shanghai, without making landfall in other places. Despite moving inland, Ampil's weakening trend remained slow. The JMA downgraded Ampil to a tropical depression on the next day, and the JTWC issued the final advisory to Ampil later that day. However, the JMA continued to track the system, and Ampil turned to northeast on July 24. The depression transited into an extratropical cyclone early on July 25, while located over Northeast China. The extratropical remnants of Ampil ultimately dissipated on July 26, over Primorsky Krai.

Preparations and impact

Ryukyu Islands

On July 20, the Japan Meteorological Agency issued a storm warning to Okinawa Island. The warning was cancelled on the next day, after Ampil passed through the island. Kitadaitōjima recorded wind gusts of. A total of 106 fights and 112 ships were cancelled on July 20–21, which affected almost 15,000 people. 29 people were evacuated in Okinawa Prefecture.

China

In advance of Ampil, more than 190,000 people in Shanghai were evacuated. Wind speed in Jigu Jiao reached, while rainfall in Hengsha Island were amounted to. As Ampil kept tracking northeastward, it affected Jiangsu and Shandong. Rainfall in Yancheng and Ju County reached and respectively. Throughout the country, Ampil killed a person and the damage were amounted to be ¥1.63 billion.