Winter avalanche activity and weather in a Canterbury alpine basin

Abstract

Abstract Weather, snow conditions, and avalanche activity for a four-month winter period in 1977 are described for Porter Heights Skifield in the Craigieburn Range, South Island, New Zealand. They are analysed to assess the origin of a large, climax-type slab avalanche event in spring. Depth hoar, which formed early in the winter, and light snowfalls produced an unstable snowpack which failed after spring warming. Other weakening processes in the snowpack are outlined. Ski areas with potential for avalanches should be monitored daily for weather observations and hazard assessments, and snowpits dug weekly throughout the winter.