Abstract: Two kinds of snows, called systematic snow and cold outbreak snow, at northern Shandong Peninsula were identified by using EOF (empirical orthogonal function). Forming mechanism of coldoutbreak snow, namely cold snow, discussed climatically. The favorable circulation pattern is lowlevel strong cold advection accompanied by deepening trough with NNW flow strengthening. Then heat flux and water vapour from the sea, as well as lowlevel stratification instability play an important role. The results show that thermal regime and evaporation in December in a year provide more advantaged capability for local snow, as accords with the observational facts. It is baroclinic boundary layer and land friction and orographic forcing that strengthen convection, so that peculiar spacial snow pattern forms at Shandong Peninsula. Further study shows that lowfrequent inner gravity wave is one of important dynamical factors which are able to inspire convection and organize snow.

Key words: seaair interaction, sealand interaction, Shandong Peninsula, coldair outbreak snow, seaair interaction, sealand interaction, Shandong Peninsula