The re-intensification of Tropical Cyclone Saudel is "uncommon but not unprecedented," said the Hong Kong Observatory's Senior Scientific Officer Kok Mang-hin, warning that its intensity remains uncertain.
His remarks came as Saudel made an unexpected return as a tropical depression on Monday after making landfall in Zhejiang and weakening into a low-pressure area.
Speaking on a radio program on Wednesday, Kok explained that Saudel regained strength because the system did not fully dissipate after making landfall in Southern China.
When the remnant cloud bands reached the southeastern coast of Hainan, the system reabsorbed oceanic energy with abundant moisture, allowing convection to regenerate.
Although it is uncommon for a tropical cyclone to strengthen at sea after moving inland, Kok said it is not unprecedented, citing Typhoon Son-tinh in 2018, which re-intensified into a tropical depression after crossing Vietnam and Laos.
Yet, Saudel's unexpected track also prompted former Observatory director Lam Chiu-ying to describe it as "bizarre" in a social media post last night, saying he could not recall a similar storm in his 50-year meteorological career.
When asked if climate change contributed to Saudel’s intensification, Kok clarified the development of a tropical cyclone is largely influenced by nearby weather systems and atmospheric conditions.
“Even a weakening system is possible to regain its strength given favorable factors,” he added.
Regarding Saudel’s path, Kok expects the system to linger over the northeastern part of the South China Sea tonight through tomorrow.
He added the storm has a higher chance of turning westward, skirting the coast of eastern Guangdong, and edging closer to the Pearl River Estuary around Friday to Saturday.
However, Kok warned that Saudel's intensity remains highly uncertain and will depend largely on its track near the eastern coast of Guangdong.
"If the system moves closer to land, frictional effects with terrain would weaken the system. Vice versa, if it remains over water longer, it would weaken more slowly with the oceanic energy nearby," he said.
He added the issuance of the Strong Wind Signal No. 3 during the weekend would depend on Saudel's distance and intensity as it passes the Guangdong coast, urging residents to stay tuned to the latest weather information.
