Super Typhoon Mangkhut is forecast to be stronger than any of the previous storms warranting Hong Kong’s highest warning signal, and is predicted to pass within 100km of the city on Sunday.
But the Hong Kong Observatory’s tracking system shows a 70 per cent chance the tropical cyclone will deviate from its predicted path over the next four days.
According to the Observatory’s latest update at 8am on Wednesday, the super typhoon is expected to be closest to the city on Sunday, about 100km southwest of the Observatory’s headquarters in Tsim Sha Tsui.
Lam Chiu-ying, former director of the Observatory, said there was still a lot of uncertainty about Mangkhut’s path because it needed to first pass through the narrow Luzon Strait between Taiwan and the Philippines before hitting Hong Kong.
“Its intensity can be reduced if it hits land on either side [of the strait],” Lam said. “Since it’s still so far away from Hong Kong, its path can easily deviate several hundreds of kilometres from the predicted path.”
The Observatory’s acting senior scientific officer, Daniel Yeung Kwok-chung, said on Tuesday that Mangkhut could be “very close” to Hong Kong by the weekend.
A typhoon is often referred to as hitting Hong Kong directly if it passes within 100km of the city.
Forecasters predict that if it sticks to its current track then at 8am on Sunday the typhoon will be about 240km southeast of the city, with winds reaching some 220km/h (137mph).
However, while the forecast path of Mangkhut indicates the most likely course the super typhoon will take, the actual path may deviate significantly, especially considering the typhoon is at least three days away from the forecast position.
The Observatory’s tracking system shows a 70 per cent probability that Mangkhut could deviate within a 500km radius from its predicted position closest to the city, leaving a lot of uncertainty over the next few days.
Even so, the forecast speed is predicted to be the strongest since records began in 1946, and stronger than any of the 15 past severe or super typhoons that warranted the highest No 10 warning signal.
Under the tropical cyclone classification system, typhoons have an intensity of between 118 and 149km/h, severe typhoons range between 150 and 184km/h, while super typhoons see a maximum wind speed near the centre of 185km/h or above.
A No 10 tropical cyclone warning signal indicates that a typhoon’s intensity is expected to reach at least 118km/h, and gusts may reach 220km/h.
Super Typhoon Hato in August last year, for example, prompted the Observatory to issue the No 10 signal. It reached 185km/h at its peak intensity. Its closest distance to the Observatory’s headquarters was 60km.
The recorded No 10 tropical cyclone with the highest intensity was Super Typhoon Hope in 1979, which reached 205km/h. It was 10km from the Observatory’s headquarters.
The notorious 1962 Super Typhoon Wanda, which killed 130 people and left 72,000 homeless, had an intensity of 185km/h and was 20km away from the headquarters.
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