The observatory issued its Increasing Gale or Storm Signal No 9 on Friday as Super Typhoon Saola barrels towards Hong Kong.

According to the present forecast track, Saola is expected to be closest to the territory around midnight, skirting within around 40 kilometres south of the Hong Kong Observatory.

Officials also said northerly winds will change gradually to east to southeasterlies locally, and areas that were previously sheltered may become exposed.

The forecaster warned that water levels will rise rapidly in low-lying areas under the influence of a storm surge.

"The water level in the eastern coastal waters of the territory will increase from around 9pm tonight. Among which, the water level at Tolo Harbour will reach a high water level of around six metres above chart datum near midnight, which is about four metres higher than the normal tide level.

"The maximum water level may reach a historical record."

Authorities urged members of the public to take all necessary precautions and seek safe shelter immediately.

The Education Bureau also announced that all schools will remain suspended on Saturday to ensure students' safety.

Meanwhile, the Government Flying Service (GFS) said it dispatched a fixed-wing aircraft to collect data on Saola.

It said the images collected showed Saola's well-defined eyewall with a tightly knit structure.

Professor Johnny Chan, an Emeritus Professor with the City University's School of Energy and Environment, told RTHK that the images captured by the GFS indicated that Saola is a very powerful and intense storm.

"For more intense typhoons (intensity refers to the strongest wind strength), the eyewall tends to be close to a complete ring," he said.

"For very intense typhoons such as Saola, there is a chance that two eyewalls can form, and hence a double-eyewalled structure. Such a structure therefore signifies that the typhoon is very intense."
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Last updated: 2023-09-01 HKT 18:21