Storm events, typically characterised by intense rainfall – when large quantities of rain fall over a short time frame – can have highly detrimental effects on land through erosion.
The projection is that ‘the frequency of extreme winds over this century is expected to increase in all regions in winter and decrease in summer’. In particular:
zonal type winds are projected and an increase in winter extreme wind frequencies having most influence in Canterbury, Otago and Southland.
blocking weather types could increase extreme summer winds in Northland, Coromandel, Bay of Plenty, Gisborne and Taranaki, with the opposite effect in winter.
cyclone (low pressure centres, not tropical cyclone) intensity is expected to decrease over New Zealand, though intensification could occur south of the New Zealand during winter, leading to a stronger pressure gradient over the South Island and an increase in extreme winds in the South Island.
The guidance provided for New Zealand is to plan for an 8% increase in rainfall intensity per degree of warming.