Hong Kong and several cities in southern China are grappling with severe flooding due to one of the heaviest rainfall events on record. This downpour, which began on Thursday, is the most significant Hong Kong has experienced in nearly 140 years, causing streets and subway stations to be submerged. The torrential rain transformed streets into raging rivers, inundating shopping centers and public transportation. Videos on social media showed people seeking refuge on cars and elevated platforms to escape the rising waters, which reached several meters high in some areas, blocking subway entrances.

The city's essential cross-harbour tunnel connecting the main island to the Kowloon peninsula was also flooded, and landslides occurred in Hong Kong's mountainous regions, blocking highways. While the heavy rain somewhat eased on Friday afternoon, authorities maintained an "amber" alert, warning that showers were expected to persist until Saturday. The previous day, a "black" warning was issued when rainfall exceeded 70mm per hour. The Hong Kong Observatory reported an hourly rainfall of 158.1 millimeters that night, the highest since records began in 1884. In just six hours, over 200mm of rain fell in various parts of the city, exceeding the usual amount for an entire month in some areas.

Southern China, including Shenzhen near Hong Kong, also experienced its most substantial rainfall since records began in 1952, leading to the suspension of hundreds of flights in Guangdong province. Local authorities in China advised residents in low-lying areas to consider evacuations, as tens of millions of people live in densely populated coastal regions.

The city of Shenzhen discharged water from its reservoirs, prompting questions about its impact on Hong Kong's flooding. However, Hong Kong's security chief, Chris Tang, stated that the discharge had no effect on the city's flooding and was safe for both Shenzhen and Hong Kong.

China's meteorological administration anticipates continued extreme rainfall in the southwestern region on Friday and Saturday. This latest deluge follows closely on the heels of two recent typhoons, Saola and Haikui, which struck southern China in quick succession and led to a citywide shutdown in Hong Kong.

It's important to note that climate change has amplified the intensity and frequency of tropical storms, resulting in more flash flooding and significant damage.