Map helps travellers weather the storms

It's the weather forecaster's secret weapon - a constantly updated radar map of the clouds over southern China. Yesterday it was made available to the Hong Kong public to help them plan business or leisure trips.

Every 12 minutes, the radar rainfall map on the Observatory's website gives the latest information about rain clouds within a 250km radius of Hong Kong - and not just where the clouds are. Unlike satellite pictures, which just show the extent of cloud cover, the radar map also indicates the likely timing and intensity of rainfall, measured in millimetres and represented by colours on the site.

Travellers can easily see whether their intended destination is likely to be hit by rain.

The map covers the whole of the Pearl River Delta region and parts of the South China Sea.

The map is compiled after water droplet information is gathered from the observatory's radar stations on Tai Mo Shan, Hong Kong's highest point, and at Tate's Cairn. Observatory assistant director Lee Boon-ying said the map was a response to growing demand from the public for more rainfall information.

'It will help people plan for their journey, particularly those who need to travel outside Hong Kong, such as to the Pearl River Delta region,' he said.

The Observatory cautions that the public should read the map carefully as radar might be deceived by varying weather conditions such as strong wind and radiation.

Mr Lee said the public would be reminded about these technical variations on the website. But he said that the forecast would be 'very accurate' most of the time.

To help the public read the radar map, the Observatory has organised courses costing $300 over the past weeks to coinciding with a trial of the new map.

More courses will be held, subject to demand.

Charlene Lam Lok-man, a Secondary Six student with a passion for geography, has taken the course.

Now checking the site before planning her outdoor activities is fast becoming a habit.

'I'll check it three or four times a week. I love swimming at beaches. If it tells me rain is likely in Sai Kung, I will go to Southern District, or vice versa,' she said.

The map is on the internet at www.weather.gov.hk/wxinfo/radars/radarc.htm.