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The weather of July 2001 was wetter and cooler than usual. The monthly rainfall of 656.4 millimetres was more than double the normal figure of 323.5 millimetres and ranked the tenth highest for July. The accumulated rainfall since January 1 amounted to 2 150.0 millimetres, 63 per cent above the normal figure of 1 316.0 millimetres for the same period and ranked the third highest for the period. The mean temperature was 28.1 degrees, 0.7 degrees below normal. Furthermore, the monthly total bright sunshine duration of 136.3 hours was the third lowest for the month. Two tropical cyclones passed close to Hong Kong and necessitated the hoisting of the No. 8 Gale or Storm Signal.
Over the northern part of the South China Sea, Severe Tropical Storm Durian intensified into a typhoon on July 1 while moving northwest towards Leizhou Peninsula. Strong easterly winds prevailed over Hong Kong and there were occasional gales offshore and on high grounds. The outer rainbands of Durian also brought heavy squally showers and thunderstorms. A waterspout was observed over the Tathong Channel between Shek O and Tung Lung Chau at around 12:50 p.m. The waterspout moved westwards and landed over Rocky Bay in Shek O five minutes later where it dissipated. As Durian made landfall near Zhanjiang on July 2 and started to weaken, local winds moderated.
Under the influence of a ridge of high pressure, the weather of Hong Kong became fine on July 3 apart from some scattered showers in the morning.
Typhoon Utor over the western Pacific skirted the northern coast of Luzon and entered the South China Sea on July 4. The weather of Hong Kong became hazy and very hot, with a maximum temperature of 33.2 degrees, the highest in the month.
Utor edged further towards the coast of Guangdong on July 5 and brought thundery showers to Hong Kong. It weakened and made landfall near Shanwei on July 6. After landing, it tracked generally westwards skirting Hong Kong within 100 kilometres to the north. Strong to gale force winds prevailed over the territory in heavy rain and squally thunderstorms. The high winds and low pressure of Utor also brought storm surge to the territory. Coupled with the astronomical high tide occurring in the morning, high sea level resulted in the inundation of some low-lying coastal areas in Tai O, Lau Fau Shan and Sheung Wan. As Utor weakened further and moved away, local winds subsided on July 7.
With a ridge of high pressure building over southeastern China, weather became fine on July 8 apart from a few isolated showers. Fine and hot weather persisted the next three days.
The southwest monsoon affected the south China coastal areas on July 12 and the weather of Hong Kong turned cloudy.
The rainbands associated with the remnant of Tropical Storm Trami which crossed the Taiwan Strait and dissipated earlier brought heavy thunderstorms to Hong Kong on the early morning of July 13. The weather improved in the afternoon and became mainly fine the next day.
An active trough of low pressure along the south China coast brought heavy rain and thunderstorms to Hong Kong on July 15. There were altogether 13 reports of flooding and Lantau Island was the most affected area. A minor landslip occurred in Lantau Island and a road subsided in Wong Chuk Hang. Temperatures dropped to a minimum of 24.3 degrees in heavy rain, the lowest in the month. The trough lingered near the coast and continued to bring unsettled weather to the territory till July 20. The weather improved on the afternoon of July 20 and there were sunny periods.
Another trough of low pressure over the northern part of the South China Sea again brought heavy thundery showers to Hong Kong on July 21. Showers gradually eased off the next day.
A ridge of high pressure over southeast China brought fine and hot weather to Hong Kong on July 23.
Tropical Storm Yutu over the Luzon Strait entered the South China Sea and intensified rapidly into a typhoon on July 24. Local winds became strong and there were squally showers and thunderstorms. Winds strengthened quickly to gale force offshore and on high grounds the next morning as Yutu came closer to the coast of Guangdong. Winds began to weaken in the evening as Yutu moved away from the territory but showers and thunderstorms continued till July 26.
A ridge of high pressure over southeast China brought sunny periods to Hong Kong on July 27. Fine and hot weather persisted for the rest of the month.
There were altogether six tropical cyclones in the South China Sea and the western North Pacific in the month.
Details of the issuance/hoisting and cancellation/lowering of various warnings/signals in the month are summarised in Table 1.1. Monthly meteorological figures and departures from normal of July are tabulated in Table 1.2.
Table 1.1 Warnings and Signals issued in July 2001
Beginning Time Ending TimeType of Warnings day/month hour day/month hour
/Signals
Tropical Cyclone Warning Signals
Name of Tropical
Cyclone Signal Number
Durian 1 30/6 0740 30/6 2220
3 30/6 2220 2/7 0920
Utor 1 4/7 1745 5/7 1045
3 5/7 1045 5/7 1930
8 NE 5/7 1930 5/7 2340
8 NW 5/7 2340 6/7 0940
8 SW 6/7 0940 6/7 1340
3 6/7 1340 7/7 1120
Yutu 1 23/7 2150 24/7 1550
3 24/7 1550 25/7 0030
8 NE 25/7 0030 25/7 1040
8 SE 25/7 1040 25/7 1940
3 25/7 1940 26/7 0615
Rainstorm Warning Signals
Amber 6/7 1230 7/7 0030
Amber 13/7 0130 13/7 0415
Amber 15/7 1445 15/7 2000
Amber 17/7 1340 17/7 1800
Amber 18/7 0610 18/7 0845
Amber 21/7 0315 21/7 0625
Landslip Warning 6/7 1800 7/7 0950
Thunderstorm Warning 1/7 0200 1/7 0700
1/7 1615 1/7 2030
3/7 0145 3/7 0745
5/7 1625 5/7 1825
6/7 1700 6/7 2400
12/7 2300 13/7 0600
15/7 0015 15/7 1900
16/7 1400 16/7 1900
17/7 0130 18/7 0900
18/7 1030 18/7 1530
19/7 0250 19/7 0835
19/7 1215 19/7 1315
20/7 0550 20/7 0650
20/7 0925 20/7 1330
20/7 2030 21/7 0700
21/7 0830 21/7 1130
21/7 1300 21/7 1500
24/7 1230 24/7 1900
26/7 1240 26/7 1540
27/7 0130 27/7 0630
Very Hot Weather Warning 9/7 1630 11/7 1630
23/7 1145 24/7 1145
29/7 0800 30/7 1630
31/7 1250 31/7 1800
Table 1.2 Figures and Departures from Normal - July 2001
Meteorological Figure of Departure from normal
Element the month above normal below normal
Mean Daily Maximum 30.5 ---- 1.0
Air Temperature (Degree Celsius)
Mean Air Temperature 28.1 ---- 0.7
(Degree Celsius)
Mean Daily Minimum 26.2 ---- 0.4
Air Temperature (Degree Celsius)
Mean Dew Point 25.0 0.1 ----
(Degree Celsius)
Mean Relative Humidity (%) 84 4 ----
Mean Cloud Amount (%) 77 12 ----
Total Rainfall (mm) 656.4 332.9 ----
Total Bright Sunshine 136.3 ---- 94.8
Duration(hours)
Mean Daily Global Solar 12.90 ---- 6.25
Radiation (MJ/Square Metre)
Total Evaporation (mm) 129.8 ---- 41.8
Remarks : All measurements were made at the Hong Kong Observatory except sunshine, solar radiation and evaporation which were recorded at King's Park Meteorological Station.
End/Thursday, August 9, 2001
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