Three-month outlook

The outlook for September 2004 to November 2004

Lower than normal mean sea-level pressures in the south Tasman Sea are expected during spring, with more west to southwest wind flow than usual over New Zealand. Surface temperatures of seas close to the country are expected to be near average.

Temperatures are expected to be near average in most regions, but above average in the eastern North Island and northern South Island. Normal or below normal rainfall is expected in the north and east of the North Island, with normal or above normal rain in the west and south of the South Island. Near normal rainfalls are expected elsewhere.

Normal or below normal soil moisture levels and streamflows are expected in the north and east of the North Island and the east of the South Island. Normal or above normal conditions are expected in the west and south of the South Island. Normal soil moisture and stream flows are expected elsewhere.

The tropical Pacific is on the verge of El Niño conditions. It is very likely that a weak El Niño will develop during spring, and ease back to neutral conditions during summer.

 

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).