Southerly buster events in New Zealand
The 'southerly buster' is a particularly intense form of southerly change which occurs along the New South Wales coast of Australia. In this study similar changes occurring in late summer in eastern New Zealand are identified and described, with emphasis on their synoptic environment. Typical features found include a sharp or sharpening trough approaching in a strong westerly flow, much warmer than usual air over New Zealand preceding the change, a shallow southerly flow following the change, and a complex meso-scale signature at the surface. The synoptic scale flow is found to have a significant influence on the formation and nature of the changes. On the mesoscale, the New Zealand southerly buster appears to have unsteady gravity current-like features similar to its Australian counterpart. A typical scenario for the occurrence of a southerly buster along the east coast of New Zealand is given.