Three-month outlook

The outlook for November 2001 to January 2002

Ocean and atmospheric conditions in the Equatorial Pacific are near normal for this time of year, and sea surface temperatures are expected to remain near average through summer 2001–02. These features continue to indicate that a near-neutral state of the El Niño–Southern Oscillation will persist for the next few months.

Sea surface temperatures around New Zealand are likely to remain above average through the early summer, which will influence summer temperatures to some extent. Large scale pressure patterns are expected to favour anticyclones east of New Zealand, with more disturbed conditions in the Tasman Sea, and a tendency for weaker westerlies over much of the country. Temperatures are expected to be above average over the north and west of the North Island, but nearer average elsewhere. Rainfalls are expected to be average to above average in the north of both islands, and closer to average elsewhere. The present state of the tropical Pacific suggests a smaller risk than usual of an ex-tropical cyclone affecting northern New Zealand over the next three months.

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).