Outlook and outcome – February to April 2002

Rainfall was below average, as forecast, in the northern North Island, Gisborne and eastern Marlborough. It was lower than expected in inland South Canterbury and Central Otago, and higher than expected in Southland.

Air temperatures were expected to be normal or above normal in all districts. This was correct for much of the country, but eastern regions from Bay of Plenty to Canterbury were cooler than predicted.

River flows were near normal, as expected, in the east of both islands. Elsewhere, flows were normal or below normal in the North Island, and below normal in the South Island.

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.