With severe tropical storm Kompasu approaching, observatory hoisted the No.8 Northeast Gale or Storm Signal at 5.20pm Tuesday.
According to the present forecast track, Kompasu will be closest to Hong Kong early Wednesday morning, skirting within 400 kilometers to the south of the territory.
Signal No.8 will remain in force until at least before sunrise on Wednesday morning. Kompasu is expected to strengthen into a typhoon when it approaches Hainan island.
Days earlier, tropical storm Lionrock triggered the hoisting of signal No.8 on Saturday.
Leung Wing-mo, spokesman of Hong Kong Meteorological Society, said such short interval between cyclones is not rare.
The sea water temperature in the vicinity of the Philippines is warm enough to create one cyclone after another, he explained.
Under global warming, research shows that there will be fewer tropical cyclones in the West Pacific and South China Sea. But they will be stronger and bring more rain, therefore potentially causing more severe damages.
The weather under Lionrock was quite different from Kompasu.
A Northeast monsoon came from the Taiwan strait last week. There was heavy rainstorm when it interacted with Lionrock.
But for Kompasu, the northeast monsoon is coming from mainland and is dryer. Even when it meets the cyclone there will be lesser rain, Leung said.
The Home Affairs Department has so far opened 24 temporary shelters in various districts and 105 people have sought refuge at the shelters.
As at 8pm Tuesday, the 1823 Government Call Centre has received nine reports of fallen trees. No reports of landslide or flooding have been received so far.
According to the Hospital Authority, as of 7pm, a man sought medical treatment at a public hospital during this typhoon period.
Britain's Queen Elizabeth carried out her first official engagement on Tuesday since spending a night in hospital and being ordered to rest by her doctors.