A case study on persistent snow-ice weather over South China from January to February in 2008 was investigated. It is shown that two Ural blocking (UB) events that have important influence on this extreme cold weather for different location, are associated with positive North Atlantic Oscillation events (NAO+). So NAO+ related UB events (NAO+ UB) are classified to four patterns as a result of their different locations, according to statistical analysis for location of UB in winter from 1979 to 2014, which are northward, southward, eastward, and westward UB events. Composited analysis reveals that the influence of southward and eastward UB events on winter cold events over China is more intense than that of the northward and westward UB events. A further study shows the NAO+ UB events are lag the NAO+ events by 3~6 days for their different locations. The result shows that the variety of zonal wind anomalies over Ural regions may be the main cause that lead to different location for NAO+ UB at the occurrence condition of NAO+. Furthermore, a statistical result for UB events and NAO events in winter from 1979 to 2014 shows that most UB events can be associated with NAO events, especially NAO+ UB events are far more than NAO- related UB (NAO- UB), and NAO+ pattern is more in favore of UB events. Therefore, the intensity of NAO- UB is stronger than NAO+ UB, and lead to more intense cold weather over China. Moreover, it is shown that the impact of NAO+ and NAO- events being absent with UB events on winter air temperatures over China is extremely weak. This hints that the UB events may be a bridge that links the winter weather over China and NAO events.
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