Analysis of the Cold Wave Weather Process in Dalian during December 29~(th)-30~(th) of 2009

Based on the daily observation data and numerical forecast products,using synoptic and diagnostic analysis methods,a cold wave process during December 29th-30th of 2009 was analyzed in south of Dalian.The results showed that,based on the warming strongly before the twice cold wave,strong cold air was accumulated in Mongolia and after Ulan Bator,Erenhot and broke out in Dalian.The circulation pattern showed a trough and a ridge at middle and high latitudes in Asia,dynamic mechanism was an upper rotating low-pressure trough and strong front zone,and the stream fields leading to outbreak of cold wave were the low trough rotating pattern during twice cold wave.After the outbreak of cold air,strong cold advection controlled Dalian and cold high pressure entered into the key areas and reached cold wave intensity.However,cold southerly circulation occurred,affecting the system and the cold air moving faster,so the south of Dalian,Lushun,Dalian,Jinzhou three stops cold wave appeared.The main forecast factors of cold wave in Dalian were put forward based on the above analyses.