Backward Trajectory Map in October 2011

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 October 2011 is now available on the following webpage:

http://www.weather.gov.hk/wxinfo/trajectory/trajectoryMonthly_e.shtml

In October 2011, the air masses reaching Hong Kong mainly originated from the northeast, indicating that the territory was under the influence of the northeast monsoon for most of the month.

Backward Trajectory of Air Mass reaching Hong Kong in October 2011

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