Tropical Storm Co-May (11W) – Tropical Cyclone Advisory #14: 0000 UTC 30 July 2025

…Co-May makes landfall on Zhoushan Island… …Expected to pass over Shanghai during the next few hours…

Current storm information:

• Position: 30.1°N 122.4°E

• Movement: NW at 10 knots (20 km/h)

• Intensity: 40 knots (75 km/h)

• Central pressure: 980 hPa

Trend:

• Rapid weakening is forecast during the next 24 hours, and Co-May is expected to weaken to a tropical depression later today.

Discussion:

CMA radar out of Shanghai indicates that the center of Co-May has made landfall on Zhoushan Island, just southeast of Shanghai, as a 40 kt tropical storm. The storm has become much better organized during the past several hours. Convective bands have wrapped more tightly into the circulation center, and radar data suggests that a partial eyewall is present to the south of the center. There is still some significant dry air intrusion present, mainly to the east of the center, but this has so far not hampered Co-May’s efforts to develop an inner core. The intensity remains 40 kts, based mainly on surface observations and Dvorak estimates ranging from T2.5 to T3.0. Notably, the central pressure is lowered to 980 hPa based on multiple observations of pressures in the low 980s in the Shanghai area.

Co-May should make landfall pretty much directly over Shanghai during the next few hours. No significant change in strength appears likely before then. Once landfall occurs, Co-May should rapidly weaken as it pushes inland and slows down, and this long-lived system will likely dissipate on Thursday.

Forecast positions and maximum winds

• 00 hrs: 30.1°N 122.4°E – 40 kts

• 12 hrs: 31.2°N 121.5°E – 35 kts

• 24 hrs: 32.1°N 120.1°E – 25 kts

• 48 hrs: Dissipated