How are typhoons tracked? Inside Hong Kong Observatory’s fight to predict extreme weather events

Even with AI at the helm, extreme weather forecasts are only reliable around 3 days in advance – so how are the weather watchers working to keep us safe?

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Why you can trust SCMP

Predicting typhoons is a matter of life or mass death yet it is backed by imperfect science. So, how have the boffins at the Hong Kong Observatory been rising to the challenge? In June this year, Typhoon Maliksi arrived in Kennedy Town. Picture: Xiaomei Chen

Martin Williams

Published: 1:15pm, 12 Aug 2024Updated: 1:55pm, 14 Aug 2024

You may find yourself on a Hong Kong beach, and you may find yourself under a blistering blue sky. And you may ask yourself, what’s this weird light in the sky?

Though there’s not a breath of wind, the sea froths, rises a metre or two, then surges. The shoreline deflates then another line of surf develops, and the water surges again. If you are acquainted with local weather lore, you may know there is probably a typhoon just out to sea, and it is probably inbound.

Nowadays, you can just take out your phone and check one of the various weather apps that provide locations, predicted movements and intensities of typhoons and other storms. These apps also feature real-time satellite and radar images, plus forecasts of winds and rain more than a week ahead.

Looking at a typhoon track predicted by an immensely powerful computer – which might have a million or more processors, compared with the two or four in your desktop – it would be easy to think this information is definitive. But a track from another computer model may disagree, and the actual outcome could differ from either of them.

Shun Chi-ming (centre) and his team at the Hong Kong Observatory watch as Super Typhoon Mangkhut approaches in September 2018. Picture: Hong Kong Observatory

Typhoon forecasts are only really reliable perhaps three or fewer days from landfall, and for rainstorms, which can also wreak havoc, there may be discrepancies with forecasts made a day or even hours in advance. In our age of supercomputers and artificial intelligence, there is no shortage of experts investigating the weather, especially in Hong Kong, which is prone to severe storms that often take the city by surprise.

“A fearful rain storm occurred at Hong Kong on May 29,” reported The Argus in Australia in June 1889. “The centre of the town is described as being simply a wreck […] Tramcars and tramlines were washed away […] Every street was flooded.” The Hong Kong Observatory reported hundreds of landslides on Hong Kong Island and at least 27 people killed.