8
Tuesday, July 25, 1972
On June 10, several upper-air disturbances moved eastwards across
the South China Sea and activated a surface trough of low pressure. As
a result, a tropical depression formed about 190 nautical miles south
of Hong Kong the same day.
The stand by signal, No. 1, was hoisted at 2.30 p.m. The tropical
depression turned onto an east-northeast course and weakened on June 11
and the stand by signal was lowered at 9.40 a.m.
Locally, it was mainly cloudy with some showers during June 10 - 11.
Winds freshened from the east and maximum gusts of 51 knots were recorded
at Tate's Cairn and 44 knots at Waglan Island.
On June 14, an active trough of low pressure formed across
south China with a series of small depressions lying along it. The
trough moved slowly southwards and affected the entire south China during
the following few days.
Rain began falling late on June 15, and for the next three days,
Hong Kong experienced almost continuous heavy rain and frequent thunderstorms,
reminiscent of the June flood of 1966.
On June 15 Dragon Boat day, a thunderstorm and heavy rain warning,
the second of the month, was issued and was renewed almost continuously
until June 19.
At the Observatory, rain was heaviest during midday on June 18 when
98.7 mm were recorded in one hour. This is only slightly less than the
highest hourly rainfall of 108.2 mm recorded on June 12, 1966.
The