Analysis on Causes for "Late Spring Coldness" in Dalian in 2008

The NCEP data was applied to analyze causes of two times "late spring coldness" in Dalian in late April and middle May of 2008. The results showed that 500hPa Baikal ridge of high pressure to maintain or enhance stability,ridge along the ridge before the accumulation of cold air flow northwest to southeast before transmission,therefore,Lake Baikal ridge of high pressure provide access for the cold air southward,so cold air can continue to decline,result in low-temperature in late April,form a "late spring coldness" ; cold vortex occurred frequency in northeast in middle May,rainy and low temperature weather was significant in Dalian,the phenomenon of "late spring coldness" appeared again.