Former Typhoon Chanthu weakened to a tropical storm east of Shanghai on Monday night. At 11:00 p.m. EDT on Monday the center of Tropical Storm Chanthu was located at latitude 31.3°N and longitude 123.9°E which put it about 150 miles (240 km) east of Shanghai, China. Chanthu was moving toward the northeast at 4 m.p.h. (6 km/h). The maximum sustained wind speed was 65 m.p.h. (105 km/h) and there were wind gusts to 80 m.p.h. (130 km/h). The minimum surface pressure was 988 mb.

Former Typhoon Chanthu weakened to a tropical storm east of Shanghai. An upper level trough over eastern China was producing southwesterly winds that were blowing toward the top of Tropical Storm Chanthu. Those winds were causing moderate vertical wind shear. In addition, the circulation around Chanthu was pulling drier air from Asia into the tropical storm. The drier air was mixing with the rainbands. The eye and eyewall at the center of former Typhoon Chanthu weakened. Thunderstorms were occurring in bands in the northeastern periphery of Tropical Storm Chanthu. Bands in other parts of Chanthu consisted primarily of showers and lower clouds. Winds to tropical storm force extended out 200 miles (300 km) from the center of Chanthu.

Tropical Storm Chanthu will be in an area where the steering winds are weak during the next 24 hours. Chanthu will not move very much during that time period. Since Tropical Storm Chanthu will not move very far, its circulation will mix cooler water to the surface. A combination of moderate vertical wind shear, drier air and cooler water will cause Tropical Storm Chanthu to weaken gradually. Southwesterly winds in the middle latitudes will start to steer Chanthu toward the northeast in a day or so.