Abstract: In January 2008, an unusual mid-high latitude blocking high pressure system caused a record-breaking freezing rain and snow storm event in southern China. Using a recently developed functional analysis tool, i.e., the multiscale window transform (MWT), the system is investigated to better understand the underlying mechanisms. By examining the multiscale pattern that is reconstructed, the blocking high is found to originate from the European region; it then became weak and moved eastward. The weakened high, however, regained energy over the Mt. Ural-Lake Beaikal region, and persisted henceforth. A new finding is that the previously identified two blocking highs are essentially one single blocking high in two stages. The MWT-based localized multiscale energetics analysis and the theory of canonical transfer were used to investigate the dynamical processes underlying the anomalous event, and find that it was driven by processes on time scales less than 32 d. Specifically, its energy came from the barotropic canonical transfer from less than 32 d scale window to 32—128 d scale window. The canonical transfer was asymmetric about the blocking high, much stronger in the west than in the east. This asymmetry was balanced through a west-to-east energy transport on the 32—128 d scale window to maintain a quasi-stable and homogeneous pattern. The above two internal processes led to the rejuvenation and stagnation of the blocking high, causing the severe, disastrous weather in southern China.