Outlook and outcome – September to November 2001

Rainfall in some central regions of New Zealand was average to above average as expected. The north and east of the North Island was wetter than forecast, while some central and southern areas of the South Island were drier than anticipated.

Air temperatures in most places were above average as was expected, although temperatures were higher than forecast in much of the east of the South Island.

Normal to below normal river flows were correctly forecast for the east of both islands. Flows were higher than expected in East Cape, Northland, and western Marlborough, and lower than forecast elsewhere.

The outcome maps shown here give the tercile rankings of the rainfall totals and mean temperatures that eventuated for these months. Terciles were obtained by dividing ranked September to November data from the past 30 years into three groups of equal frequency (lower, middle and upper one-third values) and assigning the data for the present year to the appropriate group. (Click to enlarge)

As an approximate guide, middle tercile rainfalls often range from 80 to 115% of the historical average. Middle tercile air temperatures typically occur in the range of the average plus or minus 0.5°C.