Typhoon Saomai to the north makes the path of storm difficult to predict
Tropical storm Bopha was last night downgraded to a tropical depression. Still, Hong Kong residents have been warned to prepare for strong wind and heavy rain today as the unpredictable weather system - one of three storms blowing across East Asia - powers westwards.
Squally thunderstorms are expected, with fresh northerly winds.
Bopha was about 320km east of Hong Kong at 10pm, moving at 18km/h towards Guangdong after drenching eastern Taiwan and causing landslides. But the Observatory said its movements could be difficult to forecast because of nearby Typhoon Saomai, which was swirling towards Taiwan.
Packing winds of up to 173km/h, Saomai was due to edge over northern Taiwan this morning, then head to Zhejiang and Fujian provinces - already battered by earlier storms - with wind gusts of up to 120km/h. Local authorities have warned of widespread floods and landslides in mountains.
A third tropical storm, Maria, veered away from Japan's main island of Honshu and was moving northeast at 35km/h.
The No1 storm warning signal was hoisted at 8.40am yesterday.
Some of Bopha's effects were already being felt, with air pollution soaring. In Mongkok, the roadside reading worsened steadily, from 77 at midnight on Tuesday to 147 by midnight last night. Tap Mun, or Grass Island, saw the worst air quality, with a 6pm reading of 180.