The Hong Kong Observatory issued its second black rainstorm warning of the day on Thursday, as heavy rain continued to lash the city.

The black alert was raised at 6:35 pm, just three hours after the observatory canceled the morning’s black signal at 3:05 pm and replaced it with an amber warning, the lowest in the three-tier system, at 3:40 pm. But the amber signal was quickly upgraded back to black as the rain intensified once again.

IN PHOTOS: Rampaging rain

“Please continue to exercise due care. People who have to travel should carefully consider weather and road conditions and take necessary precautions,” the observatory said.

The observatory had raised the first black rainstorm alert at 12:55 pm, warning of serious road flooding, with heavy rain exceeding 70 millimeters an hour expected.

Locally, more than 60 millimeters of rainfall were recorded over many areas, and the downpour even exceeded 160 millimeters over the western and northern parts of the New Territories.

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Authorities received reports of flooding in Tin Shui Wai, Yuen Long, Tuen Mun, and Ta Kwu Ling, according to police and local media.

As a protective measure, the MTR closed several exits of some stations, including exit A2 of Sham Shui Po Station, exit A1 of Choi Hung Station and exit B3 of Wong Tai Sin Station.

The observatory said heavy rain affected the northern part of the New Territories, especially Yuen Long, Sheung Shui, and Ta Kwu Ling and residents were advised to take necessary precautions against flash floods.

Meanwhile, the Hong Kong Special Administrative Region government was notified by the Shenzhen authority on Thursday that passenger and cargo clearance services at the Man Kam To boundary control point has been suspended until further notice, owing to the rainstorm and flooding in the area, according to a statement from the Security Bureau.

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Cross-boundary passengers and vehicles may use other land boundary control points to travel to the Chinese mainland and should check the latest traffic situation before their trip, it added.

The HKO said that the weather on Thursday afternoon and evening is expected to be cloudy with showers and a few squally thunderstorms, before improving on Friday, when the city marks the Tuen Ng Festival, popularly known as the Dragon Boat Festival.  

Gang Wen contributed to the story.