The start of hurricane season

June 1st is the start of the Atlantic hurricane season. Above is a time lapse video of Tropical Depression Nangka, taken from 7am to 9pm, passing over Hong Kong on June 26, 2009. The video's title identifies it as a Typhoon, but it had only been a Tropical Storm when it passed over the Philippines and it was downgraded to a Tropical Depression before making landfall in China.

Still, it gives a good view of how rain bands sweep through during tropical weather systems. As you can see, some of them can be quite torrential. Near the end of the video you can also see the direction of cloud movement shift as the center of the system passes Hong Kong.