Backward Trajectory Map in December 2013

Hong Kong was mainly influenced by the winter monsoon during the month, and most of the air masses reaching the territory originated from the north and the northwest.

Monthly maps of backward trajectory over the past 72 hours showing origins of air masses affecting Hong Kong can be found at the following webpage:

http://www.weather.gov.hk/en/wxinfo/trajectory/trajectoryMonthly.shtml

Backward Trajectory of Air Mass reaching Hong Kong in December 2013