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April

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 31 – 7 April 2003

March’s climate: The El Niño episode is continuing to weaken. Enhanced convection persisted over Western Kiribati, but it was weaker than in most recent months. The South Pacific Convergence Zone (SPCZ) remained further east than usual, extending from the Cook Islands to the south of Pitcairn Island, with above average rainfall from the Austral Islands to southern French Polynesia. Rainfall totals were also above average in southern New Caledonia, western and central parts of Fiji, and parts of central and southern Tonga. A large region of suppressed convection and below average rainfall occurred in the southern near-equatorial region east of Tokelau Islands. This region extended well to the east of the Marquesas Islands of northern French Polynesia. Tropical cyclone ‘Erica’ devastated parts of New Caledonia near the middle of the month.

Tropical cyclone update: Two tropical cyclones – ‘Erica’ and ‘Eseta’ – bring the season’s total to eight.

ENSO and sea surface temperatures (SST): Based on present conditions, and the recent model forecasts, the present El Niño event is expected to return to neutral by the early southern hemisphere winter 2003. The Southern Oscillation Index (SOI) showed little change to –1.0 in March but sea surface temperatures (SSTs) in the equatorial Pacific and other indicators of the El Niño Southern Oscillation (ENSO) eased further during March.

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

Three month outlook: Enhanced convection in the equatorial Pacific is likely to result in above average rainfall for Western and Eastern Kiribati. Rainfall is also expected to be average or above average for the Solomon Islands, Tokelau and Samoa. Average or below average rainfall is expected in New Caledonia and Fiji with below average rainfall for the Marquesas Islands.

Feature article: ENSO Update.

Sources of South Pacific rainfall data.


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