Global setting & climate outlook

Global setting and climate outlook

Sea surface temperatures around New Zealand

Isopods. [NIWA]

New Zealand SST (click to enlarge).

Sea surface temperature anomalies in the New Zealand region were near zero in October. The three month average for August to October was also near zero. SST anomalies have been decreasing for over a year, after a marked warming in early 2005. The sea surface for much of the region around New Zealand is now cooler than normal, but an area of positive anomalies still lies to the north of the Chatham rise.

El Niño now established

Difference from average global SST (click to enlarge).

Monthly SOI values (click to enlarge).

The tropical Pacific ocean and atmosphere have developed into a clear El Niño state. Sea surface temperature anomalies have risen in the eastern Equatorial Pacific, while negative anomalies have strengthened in the western Pacific.

Outlook for November 2006 to January 2007

Regional outlook (click to enlarge).

A moderate El Niño event in the tropical Pacific will have an influence on New Zealand’s climate through to the end of summer 2006–07. Stronger than average southwesterly airflow is expected over the country; below average pressures are likely to the southeast of New Zealand.

Temperatures are expected to be average or below average in all regions. Rainfall is expected to be normal or below normal in all regions except the west of the South Island, where above normal rainfall is expected. Streamflows and soil moisture levels are likely to be normal or above normal in the south and west of the South Island, and normal or below normal in other regions.

Normal tropical cyclone risk is expected in the New Zealand region during the ‘cyclone season’. This means there is an 80% chance, between November and May, of an ex-tropical cyclone passing within 500 km of the country.