The application of lightning density map in the analysis of a severe rainstorm case in Hong Kong

On 22 July 2010, Typhoon Chanthu made landfall over the coast of western Guangdong at about 400 kilometres west of Hong Kong. The outer rainbands of Chanthu brought intense rainstorms to Hong Kong on that day where more than 150 millimetres of rainfall were registered. The severe rainstorms claimed four lives. More than 40 flooding and 10 landslides were reported. A waterspout was also observed over offshore waters. This paper will review the rainstorm case, particularly on the application of lightning density maps in the analysis. It was found that lightning density maps were useful in monitoring the movement and development of thunderstorms. Areas with intensifying lightning density matched properly with the areas affected by developing radar echoes. As the density maps resembled the appearance of radar images and have a higher updating frequency than that of radar images, it has good potential to provide more timely guidance to the forecaster in terms of thunderstorm nowcasting.