Turbulence is sometimes associated with a cold front, where cold air meets warm air during its advance.  In the afternoon of 23 January 1997, around 5:30 p.m. Hong Kong time, an aircraft reported turbulence when attempting to land in Hong Kong.   This was found to be related to the passage of an intense cold front, as evidenced by the weather chart below for 5 p.m Hong Kong time that day.  Since the cold front also brought clouds and rain, this event was not CAT.