Global setting and climate outlook
Global setting and climate outlook
La Niña to stay for summer
Difference from average global SST (click to enlarge).
Monthly SOI values (click to enlarge).
La Niña conditions are well-established in the central and eastern equatorial Pacific, and are expected to persist through to the end of summer 2007–08. The pattern of sea surface temperature (SST) anomalies in the tropical Pacific now exhibits a clear La Niña signature, with a well-developed cold tongue extending from the South American coast to the Date Line. However, SST anomalies remain small or slightly negative in the Indonesian region.
Sea surface temperatures(SST) around New Zealand
New Zealand SST (click to enlarge).
Sea surface temperature (SST) anomalies in the New Zealand region went slightly negative overall for October at –0.1°C, with the August to October average anomaly about +0.2°C. At the end of October, SST anomalies werenegative south of Chatham Rise and southeast of the South Island but were near zero elsewhere. During summer, SSTs are expected to be above normal around the North Island and near normal around the South Island.
Outlook for October to December 2007
Regional outlook (click to enlarge).
Over the early summer, mean sea level pressures are expected to be higher than normal to the south of New Zealand, with weaker than normal westerly winds across much of the country.
Air temperatures are likely to be above average or average in all districts. Rainfall is expected to be normal or above normal in the northern North Island, normal or below normal over most of the South Island, and near normal elsewhere. Normal or above normal soil moisture levels and stream flows are likely in the northern North Island; normal or below normal conditions are likely in the west, south, and east of the South Island, and normal conditions elsewhere.
There is a slightly lower than normal chance of an ex-tropical cyclone passing within 500 km New Zealand during November to May. Should such a cyclone approach New Zealand, the regions most at risk are the north and northeast of the North Island.