Backward Trajectory Map in May 2013

In May 2013, the air masses reaching Hong Kong mostly originated from the south and southwest, indicating that the territory was mainly affected by troughs of low pressure or southwesterly airstreams.

Backward Trajectory of Air Mass reaching Hong Kong in May 2013
( http://www.weather.gov.hk/en/wxinfo/trajectory/trajectoryMonthly.shtml)

By using computer model analyses, the past 72-hour backward trajectory of the air mass reaching Hong Kong is estimated by the Observatory on a daily basis. The daily trajectories are compiled into the Monthly Backward Trajectory Map.

For daily, monthly or seasonal backward trajectory maps, please visit the following webpages:

Daily Backward Trajectory Map
http://www.weather.gov.hk/en/wxinfo/trajectory/trajectory.shtml

Monthly Backward Trajectory Map
http://www.weather.gov.hk/en/wxinfo/trajectory/trajectoryMonthly.shtml

Seasonal Backward Trajectory Map
http://www.weather.gov.hk/en/wxinfo/trajectory/trajectorySeasonal.shtml