December

An overview of the present climate in the tropical South Pacific Islands, with an outlook for the coming months, to assist in dissemination of climate information in the Pacific region.

Number 39 – 5 December 2003

November’s climate: Below average rainfall persisted over much of the equatorial Southwest Pacific, with suppressed convection over much of Western and Eastern Kiribati, Tokelau, and also parts of northern French Polynesia. Rainfall was also below average over the southern Coral Sea, and parts of New Caledonia, Fiji, and Niue. Low rainfall has persisted for many months in parts of Eastern Kiribati, and Fiji. The South Pacific Convergence Zone (SPCZ) extended east from north of Papua New Guinea to Samoa, being more active than usual over the Solomon Islands. Enhanced convection occurred from the Caroline Islands southeast to southern Vanuatu. Air temperatures were above average in Tuvalu and Tonga, and below average in New Caledonia and the Southern Cook Islands. There have been no tropical cyclones so far this season.

ENSO and sea surface temperatures (SST): Even though the equatorial Pacific is in a neutral state, equatorial sea surface temperatures (SSTs) remain higher than normal, especially in the western Pacific. The Southern Oscillation Index (SOI) was -0.5 for November. Almost all global climate models indicate neutral conditions (with positive SST anomalies) through to early 2004. A number of models suggest a warm event developing for the southern hemisphere winter of 2004.

Forecast validation: How well are we doing with our predictions?

Three month outlook: Enhanced convection is expected in the equatorial region extending from Western Kiribati southeast to Tuamotu Islands, including the Solomon Islands, Tuvalu, Tokelau and Wallis and Futuna, where rainfall is expected to be average or above average. Average or below average rainfall is likely for New Caledonia and the Marquesas Islands, while below average is forecast for Eastern Kiribati. Near average rainfall is most likely elsewhere in the region.

Feature article: Defining ENSO Events.

Sources of South Pacific rainfall data.

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