XN000022-1987-10-12 — Page 12

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MONDAY, OCTOBER 12, 1987

BETWEEN SEPTEMBER 13 AND 24, MODERATE EASTERLY WINDS PREVAILED OVER HONG KONG BUT THEY WERE OCCASIONALLY FRESH OFFSHORE. THE WEATHER THROUGHOUT THIS PERIOD WAS GENERALLY CLOUDY WITH INTERMITTENT SHOWERS. SOME OF THESE SHOWERS WERE QUITE INTENSE BUT ISOLATED. FOR EXAMPLE, SHORTLY BEFORE MIDNIGHT ON SEPTEMBER

21, A HEAVY DOWNPOUR BROUGHT OVER 50 MILLIMETRES OF RAIN TO THE ROYAL OBSERVATORY BUT ONLY A FEW MILLIMETRES WERE RECORDED OVER THE WESTERN PART OF THE NEW TERRITORIES. THE HEAVY RAINFALL CAUSED SOME MINOR FLOODING IN THE URBAN AREAS.

ON SEPTEMBER 25, A TROUGH OF LOW PRESSURE FORMED OVER CENTRAL CHINA AND BEGAN TO MOVE SOUTHWARDS. THIS TROUGH BECAME A COLD FRONT LATER IN THE DAY AND REACHED THE SOUTH CHINA COAST THAT NIGHT. SHOWERS AND THUNDERSTORMS ON SEPTEMBER 25 HERALDED THE PASSAGE OF THIS COLD FRONT THROUGH HONG KONG. THE TEMPERATURE ALSO DROPPED TO 21.7 DEGREES CELSIUS ON THE MORNING OF SEPTEMBER 26, WHICH IS THE LOWEST TEMPERATURE RECORDED SO FAR THIS AUTUMN.

NORTHERLY WINDS, CLOUDY SKIES AND SOME RAIN KEPT THE TEMPERATURES DOWN ON SEPTEMBER 26. WITH THE WINDS TURNING TO EASTERLY ON SEPTEMBER 27, TEMPERATURES GRADUALLY CLIMBED TO NEAR-NORMAL VALUES DURING THE REMAINING FOUR DAYS OF THE MONTH. THE WEATHER REMAINED CLOUDY THROUGHOUT THIS PERIOD WITH SOME LIGHT RAIN.

A TOTAL OF SEVEN TROPICAL CYCLONES OCCURRED OVER THE WESTERN NORTH PACIFIC DURING SEPTEMBER.

1+

DURING THE MONTH, NO AIRCRAFT WAS DIVERTED FROM HONG KONG DUE TO ADVERSE WEATHER. THUNDERSTORM WARNINGS WERE ISSUED ON SEPTEMBER 2, 3, 6, 18, 21, 22, 24 AND 25.

THE ONLY SIGNAL HOISTED DURING THE MONTH WAS AS FOLLOWS:

WEATHER SYSTEM

SIGNAL

DATE AND TIME OF HOISTING

DATE AND TIME OF LOWERING

TYPHOON GERALD

1

SEPTEMBER 9.

12 NOON

+

SEPTEMBER 10,

11 AM

THE MONTH'S FIGURES AND DEPARTURES FROM NORMAL WERE:

SUNSHINE

153.1 HOURS; 35.4 HOURS BELOW

NORMAL

GLOBAL SOLAR RADIATION

14.04 MJ/SQUARE METRE ; 2.78

RAINFALL

MJ/SQUARE

METRE BELOW NORMAL

158.3 MM 162.1 MM BELOW

NORMAL

/CLOUDINESS