Outlook and outcome – March to May 2002

Rainfall was below average as forecast in the east of the North Island. Southland and the northwest of the South Island had normal or above normal rain as expected. Rainfall was lower than expected in Waikato and Bay of Plenty, and in central South Island areas, including west Otago and south Westland.

Air temperatures were near normal in many districts, as predicted. However Nelson and Marlborough were warmer than expected, as were parts of Canterbury and east Otago.

River flows The east coast of the South Island had normal flows, as was predicted. Northland and the west and south of the South Island had normal to below normal flows, and the rest of the country had below normal flows.

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 February to April 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.