Southerly changes on the east coast of New Zealand

A common feature in all four cases was the shallowness of the southerly flow for some hours after the surface wind change. The top of the southerly flow layer was less than the typical height of the Southern Alps (2000 m). Above this there was usually a maximum of the northerly component of the flow at or just above mountain-top levels and in three cases the prefrontal low-level flow was dominated by a warm northwesterly foehn. In the central South Island the northwards motion of the southerly change line at the surface was more rapid on the coast than inland. In this and other respects, the changes had many of the characteristics of "southerly busters' in southeastern Australia, and it seems likely that the dynamical mechanisms of both kinds of fronts are similar. -from Authors