Global setting & climate outlook

Global setting

El Niño-Southern Oscillation remains neutral

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), and is expected to remain so through the rest of 2005.

The SOI was slightly positive in September (+0.3), and the 3-month July to September mean remained near zero (-0.2).

Sea surface temperatures (SST) around New Zealand

Mid-depth zone: mixed community of milfoils and charophytes. [NIWA]

New Zealand SST (click to enlarge).

The New Zealand average SST anomaly was about +0.8 °C in September, a rise from August (+0.6 °C) and July (+0.5 °C). This increase was very likely to be due to the predominant anticyclonic conditions over New Zealand in the past three months. SST anomalies are positive over much of the Tasman Sea, and east of New Zealand as far as the central South Pacific. Sea surface temperatures around New Zealand are expected to remain above average until the end of the year.

Outlook for October 2005 to December 2005

 

Regional outlook (click to enlarge).

Local atmospheric circulation patterns are likely to favour more northerly quarter airflow than usual over the country for October-December.

Air temperatures are expected to be above average in all regions, with an upper tercile probability of 50% or more.

Rainfalls are likely to be normal or above normal in the North Island and in Nelson-Marlborough, and normal further south.

Normal soil moisture levels and streamflows are expected in most areas, apart from the South Island east coast where there is a high probability of dry soil conditions and lower than normal flows (55% and 60% respectively).