Rare occurrence of thunderstorms in December

The Thunderstorm Warning Signal issued by the Hong Kong Observatory last night (Thursday, 19 December 2002) is the first Thunderstorm Warning in December since the operation of the Thunderstorm Warning System in 1967. While the warning was in force last night, reports of thunderstorms were received in many parts of the territory, including Chek Lap Kok, Sha Tin and Tin Shui Wai.

A moist and warm maritime airstream prevailed over Southern China in the past couple of days. With the arrival of a cold front at the coastal region last night, the associated cooler airmass encountered the warm and moist airstream. Together with a relatively unstable atmosphere, they triggered the formation of the thunderstorms.

According to past records, the date closest to December with a Thunderstorm Warning in force is on 3 January in 1995.

For latest weather forecast, please refer to the following webpages:

http://www.weather.gov.hk/wxinfo/currwx/flw.htm (Local Weather Forecast) and
http://www.weather.gov.hk/wxinfo/currwx/f5d.htm (5-Day Forecast).