Typhoon Vicente took most people by surprise with its hurricane-force winds - not least atmospheric scientists puzzled by how it intensified in such a short time and distance.
'The typhoon's action was beyond the expectation of many scientists watching it,' said Professor Johnny Chan Chung-leung, dean of the School of Energy and Environment at City University.
'Even the United States, Japan and China didn't get it right this time. And everyone is discussing it now.'
A chair professor of atmospheric science, Chan said Vicente went through a rare 'rapid intensification' as it was developing in the South China Sea, transforming from a tropical depression into a severe typhoon within two days.
Chan said Vicente might have encountered a warm pool of water in the sea or there might have been some atmospheric flow pattern changes that gave rise to such rapid transformation. But more analysis was needed to find out the causes.
'There have been many advances in predicting the movement of a typhoon, but little progress in how to predict changes in intensity,' he said. Chan believed the typhoon, with a near-centre speed of 155km/h, brought hurricane force winds as it edged close to western Hong Kong.