Hong Kong on Thursday morning recorded more than 10,000 cloud-to-ground lightning strikes amid an amber rainstorm warning that lasted for less than three hours.
More than 5,000 cloud-to-ground lightning strikes were recorded between 6am and 6.59am, while over 3,000 such occurrences were observed at an hourly rate from 4am to about 6am, according to the Observatory.
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Social media users also posted footage of lightning, with one capturing a dramatic strike at Wo Tin public-housing estate.
Clarence Fong Chi-kong, a meteorologist at the Macau-based ESCAP/WMO Typhoon Committee under the UN, said Hong Kong’s amount of lightning strikes in the morning was “relatively high” and linked to the outer rain bands of Typhoon Mawar.
He added that it was relatively rare to see lightning strike flats.
“There may be items carrying static electricity near the window or outside the wall,” Fong suggested of the incident captured in the video.
According to the Observatory, lightning can occur under unstable weather systems, such as disturbances in airstreams, troughs of low pressure or tropical cyclones.
Hong Kong logs hottest day of year as temperature soars to 34.6 degrees at Observatory
The amber rain signal, raised at 5.15am and cancelled at 8am, means heavy rain has fallen or is expected to fall generally over the city, exceeding 30 millimetres in an hour. Some districts were warned of the risk of serious flooding.
“Rain is particularly heavy in Peng Chau in Islands district and Tuen Mun district, with more than 70 millimetres of rain [having fallen] hourly or expected to fall,” the forecaster said at 6.23am.
“Violent gusts reaching 100km/h or above may continue to affect Hong Kong,” it warned, adding the public should seek safe shelter and leave bodies of water immediately.
The Labour Department reminded employers and contractors to adopt necessary work arrangements and take suitable measures to protect the safety of staff carrying out electrical work.
Meteorologists earlier said Typhoon Mawar, despite bypassing the city, had a far-reaching impact on Hong Kong, bringing record temperatures for May and causing serious air pollution.
Mawar is expected to move across seas east of Taiwan on Thursday and Friday, towards the south of Japan before weakening gradually.
Hong Kong Observatory issues amber rainstorm warning, cancels it 1 hour later
Hong Kong recorded its hottest day of the year so far on Wednesday as the maximum temperature at the Observatory in Tsim Sha Tsui soared to 34.7 degrees Celsius (94.5 Fahrenheit), with the mercury at various districts reaching 35 degrees or above.
The heat prompted a seven-hour amber alert for outdoor workers, the lowest in a three-tiered warning system under which employees are advised rests of 15 to 45 minutes an hour based on labour intensity.
Executive director of the Occupational Safety and Health Council Bonnie Yau Man told a Thursday radio programme his group had launched a thematic website and hotline to calculate rest time for users.
Workers can answer simple questions on labour intensity, environment, ventilation and heat dissipating devices to check their rest times under different warning signals.
Yau also suggested workers rest in shifts to reduce the impact on schedules, stressing that employers should prioritise staff health and safety.
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But Hong Kong Construction Association executive director Godfrey Leung King-kwok on the same show argued breaks were “difficult to execute”.
“Like pouring concrete, we cannot stop the process,” Leung said. “Arranging rest shifts will require a lot of manpower and the arrangement is complicated.”
He added contractors had been giving rest time, drinks and watermelons to workers, even before the heat-warning system was introduced.
Leung said he hoped the Construction Industry Council would update sector guidelines based on the actual situation to facilitate companies.
More from South China Morning Post:
- What’s wrong with Hong Kong’s weather? How climate change has caused recent erratic conditions
- Why Typhoon Mawar is causing Hong Kong’s soaring temperatures, intense pollution without making direct hit
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