HAIKOU, July 30 (Xinhua) -- South China's Hainan Province Tuesday issued an alert for a forthcoming typhoon, ordering to suspend all ferry services in Qiongzhou Strait starting Wednesday morning.

The ferry services across the Qiongzhou Strait are to be halted starting 7 a.m. while train services into and out of the tropical island will also be suspended, the Haikou maritime safety administration said Tuesday.

The provincial meteorological administration said a tropical depression was formed Tuesday afternoon in the northern waters of the South China Sea and was expected to upgrade to a typhoon on Wednesday.

The tropical depression was about 540 km southeast of Haikou, the provincial capital, at 9 p.m. Tuesday, and strengthening while moving northwestward 20 km per hour.

The typhoon was forecast to bring heavy rains and strong gales to Hainan and its coastal waters from Wednesday to Thursday.

It is expected to make a first landfall in areas from Qionghai of Hainan to Dianbai of Guangdong Province from Wednesday night to early Thursday morning.