May

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 32 – 8 May 2003

April’s climate: The El Niño episode is now over, with enhanced equatorial easterlies across the Pacific. The South Pacific Convergence Zone (SPCZ) was displaced further north than average, with enhanced convection and above average rainfall in many areas from Tuvalu to the Society Islands of French Polynesia. Rainfall totals were also above average in southern Vanuatu, parts of New Caledonia, the Kermadec Islands northeast of New Zealand, and areas of the Austral Islands in southern French Polynesia. The last week of the month was unsettled with flooding and heavy rainfall in some of Fiji’s Central Division areas, as well as in parts of New Caledonia. A large region of suppressed convection and below average rainfall extended from Western Kiribati well to the east of the Marquesas Islands of northern French Polynesia. Air temperatures were above average throughout much of the tropical Southwest Pacific, as far east as Pitcairn Island. There have been nine tropical cyclones so far this season, with one occurrence in April.

ENSO and sea surface temperatures (SST): The El Niño event that has been affecting the region since middle of 2002 has dissipated. Most of the global climate models and oceanic observations show a return to neutral conditions which are likely to continue through the southern hemisphere winter and into spring. The Southern Oscillation Index (SOI) eased to -0.6 in April.

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

Three month outlook: Average or above average rainfall is likely in Western and Eastern Kiribati, the Solomon Islands, Tuvalu, Tokelau, and the Society Islands. Rainfall is expected to be average or below average in Fiji, Tonga, Niue and the Tuamotu Islands. Below average rainfall is likely in the Marquesas Islands.

Feature article: Tropical Cyclone summary for the 2002/03 season.

Sources of South Pacific rainfall data.

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