Sea level rises normally less than 1m during a tropical cyclone because of its low central pressure. The strong winds of a tropical cyclone converge to the centre and may raise the sea level 6-10m higher than normal.
Storm Surge lead from a tropical cyclone possesses a main threat to the lives and properties of all residents living along the coastal areas.
Severe flooding occurs frequently within some low-lying areas of Macao whenever a tropical cyclone approaches, threatening lives and properties of all residents while causing gigantic economic loss. A categorized (3 levels) Storm Surge Warning had thus been developed to ensure the safety of lives and properties.