Three-month outlook

The outlook for February 2003 to April 2003

Early autumn is expected to be influenced by enhanced anticyclone activity over the Tasman Sea with episodes of stronger than normal southwesterly winds across New Zealand. The moderate El Niño event in the tropical Pacific is weakening, but its influence should be felt on New Zealand’s climate into April.

Temperatures are expected to be near average over the North Island and northern South Island, and average or below average over the rest of the South Island.

Normal or below normal rainfall is expected in the North Island, and south and west of the South Island. Below normal rainfall is likely in eastern South Island regions.

Below normal soil moisture levels and river flows are expected in eastern regions. Normal to below normal conditions are expected elsewhere.

There is a near-average risk of a tropical cyclone affecting New Zealand during the remainder of the cyclone season. On average, one ex-tropical cyclone affects the country during the cyclone season.

A. Climate models give no strong signals about how the climate will evolve, so we assume that there is an equal chance (33%) of the climate occurring in the range of the upper, middle or lower third (tercile) of all previously observed conditions.

B. There is a relatively strong indication by the models (60% chance of occurrence) that conditions will be below average, but, given the variable nature of climate, the chance of average or above-average conditions is also shown (30% and 10% respectively).