The Weather of June 2001

    The weather of June 2001 was marked by persistent heavy rain and squally thunderstorms under the repeated influence of active troughs of low pressure near the south China coast. The monthly rainfall amounted to 1083.6 millimetres, about three times the monthly normal figure of 376.0 millimetres. This is a new record for June, the previous record being 962.9 millimetres in June 1966. The accumulated rainfall since 1 January was 1493.6 millimetres, 50 per cent above the normal figure of 992.5 millimetres for the same period. The month was slightly cooler than usual. The mean temperature was 27.6 degrees, 0.2 degrees below normal.

    Persistent downpour necessitated the issuance of the Rainstorm Warning Signal on 14 days of the month, 5 of which with the Red Warning. The Rainstorm Warning Signal was issued for nine consecutive days from 5 June to 13 June, the longest period on record since the revised Rainstorm Warning System was operational in 1998.

    A trough of low pressure over the northern part of the South China Sea brought showery weather to Hong Kong on the first two days of the month.

    After the trough dissipated, there were sunny intervals on 3 June. Meanwhile, another trough of low pressure formed over south China and brought squally thunderstorms to the territory in the late evening. Apart from isolated showers, there were sunny periods on 4 June.

    The trough moved southwards on 5 June and brought thunderstorms to Hong Kong. One man was killed and three other people were injured by lightning. The trough stayed along the coast of Guangdong till 12 June. Throughout the period, unsettled weather persisted with torrential rain and squally thunderstorms which caused widespread damage to the territory. Altogether, there were 65 reports of landslip and 262 reports of flooding. The New Territories was worst hit, with over 800 millimetres of rainfall recorded at Fanling. Flood waters almost rose to the roofs of two-storey village houses. Of the many villagers stranded, 26 people were rescued by helicopters and 113 people by firemen in dinghies. Thirteen of them were injured. Some 17 hectares of fish ponds and 227 hectares of farmland belonging to 1 200 households were inundated, costing about eight million Hong Kong dollars. The roof of a hut in Lei Yue Mun collapsed and injured a man. Another two village huts collapsed in a landslip in Fanling. Two stone bridges in Pat Heung and Kam Tin were damaged by torrents. A road in Tung Chung subsided. The minimum temperature of 23.7 degrees recorded on 7 June during a thunderstorm was the lowest in the month.

    The trough along the coast dissipated on 13 June but another one over inland Guangdong soon moved south and brought more thundery showers to Hong Kong.

    After the trough moved southwards away from coastal areas, the weather improved on 14 June and there were sunny intervals. Apart from a few thunderstorms in the morning, there were sunny intervals on 15 June.

    Under the influence of the southwest monsoon, there were scattered showers and thunderstorms on 16 June.

    With the subtropical ridge of high pressure extending over southeastern China, the weather turned mainly fine and hot on 17 June. Fine weather continued for the next couple of days.

    Active southwesterly winds brought some showers to Hong Kong on 20 June. Apart from isolated showers, the weather was mainly fine and hot the next day.

    On 22 and 23 June, Typhoon Chebi to the east of the Philippines moved across the Balintang Channel and Bashi Channel into the Taiwan Strait. The weather in Hong Kong was sunny and very hot with temperatures reaching a maximum of 33.2 degrees on both days, the highest in the month. It was hazy at first on 23 June but thunderstorms developed during the evening and continued till next morning. Chebi took a northerly track afterwards and moved away from Hong Kong.

    A trough of low pressure over the northern part of the South China Sea brought heavy thundery showers to Hong Kong on 25 June. Thundery showers continued the next two days. Winds also strengthened from the southeast. Over 200 millimetres of rainfall were recorded in the New Territories on 27 June. There were altogether 40 reports of flooding and 8 reports of landslip. More than 10 people in Sheung Shui were rescued by firemen in dinghies. A van in a car park was swept away by torrents in Sai Kung.

    With the extension of the ridge of high pressure over the Pacific to cover southeastern China, rain eased off on 28 June and the weather became fine. Fine weather continued the next day apart from isolated showers.

    A tropical depression formed over the South China Sea on 30 June and was named Durian. It moved northwestwards towards Leizhou Peninsula and intensified. Its outer rainbands brought thundery showers to Hong Kong early during the day and local winds strengthened in the late evening.

    Chebi and Durian were the only two tropical cyclones which occurred in the South China Sea and the western North Pacific in the month.