Backward Trajectory Map in April 2010

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. The Monthly Map for April 2010 is now available on the following webpage:
http://www.weather.gov.hk/wxinfo/trajectory/trajectoryMonthly_e.shtml

As revealed from the Monthly Map in the figure below, the air masses reaching Hong Kong in April 2010 mainly followed a route from the northeast, while air masses on some of the days originated from the South China Sea and the Northwest Pacific.

Backward Trajectory of Air Mass reaching Hong Kong in April 2010

For Daily or Seasonal Backward Trajectory Maps, please visit the following webpages:

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

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