Expect rainy days - but no more than usual

It's not raining more than usual in Hong Kong; it only feels like it sometimes, as the city gets pounded with increasingly intense downpours due to global warming, the Observatory said yesterday in presenting its annual forecasts.

This year will see normal - 2,300mm - to above-normal rainfall despite the heavier downpours, the weather service predicted.

Sharon Lau Sum-yee, assistant director of the Observatory, explained the link between global warming and intense downpours. 'It's like water boiling: the hotter the weather, the more water will evaporate - and so the heavier the rainfall.'

In the past it usually took about a decade to break a rainfall-per-hour record, she said. Now the records are falling every two to three years. The record for a one-hour downpour, 145.5mm, was set in June 2008.

As for this year's typhoon season, the Observatory predicted between five to eight tropical cyclones would hit the city, beginning in early June or even sooner. Last year the service predicted six to nine typhoons, and the actual number - six - was the annual average for the past 30 years.

To better warn people about volatile weather, the Observatory will begin using two weather icons instead of one in its public notices, to draw attention to the weather change. 'This will enable us to provide more meticulous and up-to-date weather forecasts to the public,' Observatory director Shun Chi-ming said.

For example, if a sunny morning and rainy afternoon is forecast, the Observatory will release a sunny icon with an arrow pointing towards a rain icon. The double icon will be used just for daily forecasts initially, but if it gets a good response it will be used for the seven-day forecast, Shun said.

A smartphone application will also be launched giving rainfall updates by location. The Observatory will open its doors to the public on Saturday and Sunday to celebrate World Meteorological Day on Friday.