The Observatory said it will issue the Standby Signal No 1 as early as Friday night.

The signal will be issued as a tropical cyclone to the east of the Philippines comes within 800 kilometres of Hong Kong some time between late Friday and early Saturday, according to the present forecast.

The weatherman said on Thursday the cyclone will continue to intensify and edge closer to the vicinity of the coast of western Guangdong afterwards.

It might consider issuing the No 3 warning signal on Saturday and higher typhoon warning signals on Sunday, depending on the storm's distance from the Pearl River Estuary and changes in local wind conditions.

Heavy squally showers and thunderstorms will hit the SAR from Sunday onwards.