Global setting & climate outlook

Global setting

El Niño-Southern Oscillation neutral at least until autumn

Difference from average global SST (click to enlarge).

Monthly SOI values (click to enlarge).

The tropical Pacific is in a neutral state (no El Niño or La Niña), although sea surface temperatures near the Date Line remain a little above average.

The SOI was positive in October (+1.0), but the 3-month August to October average was near zero (+0.1). Near neutral conditions are expected through to autumn 2006.

For the coming cyclone season (November-April), normal cyclone activity is expected. For New Zealand, this means a 2 in 3 chance of a cyclone passing near the country, with Northland and Gisborne being most at risk.

Sea surface temperatures (SST) around New Zealand

New Zealand SST (click to enlarge).

The New Zealand SST anomaly was lower in October than in September, as a result of more frequent southeasterly airflows across the New Zealand region. SSTs will remain above average over much of the Tasman Sea, and east of New Zealand as far as the central Pacific Ocean.

Outlook for November 2005 to January 2006

 

Regional outlook (click to enlarge).

Atmospheric circulation patterns over New Zealand during November-January are likely to be more anticyclonic than usual, with enhanced southwesterly airflows over the North Island, and more frequent southerly quarter airflows over the South Island.

Sea surface temperatures around New Zealand are expected to remain slightly above average to the end of January 2006. Air temperatures are expected to be average or above average in all regions of New Zealand.

Rainfalls are likely to be near normal in all regions, except for normal or below normal in the east of the North Island. Normal soil moisture levels and streamflows are expected in the North Island. Generally dry conditions are expected in the South Island.