The dynamics of the southerly buster

The southerly buster is a particularly abrupt form of cold front which occurs frequently in the coastal regions of New South Wales, mainly in the spring and summer. Observational evidence indicates that it is associated with the deformation of a cold front caused by its interaction with the Great Dividing Range. A simple dynamical model of this phenomenon is developed, and it is proposed that the southerly buster is essentially a coastally trapped gravity current, held against the mountains by the Coriolis force and in transverse geostrophic balance. The available observations generally support this theory, although the variability from case to case indicates that more detailed observations are necessary for a complete understanding.