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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 19 – 10 April 2002

March’s Climate: An extensive area of enhanced convection occurred over equatorial waters about and west of the date line, from Papua-New Guinea to Western Kiribati, with another convective band associated with a southward displacement of the South Pacific Convergence Zone (SPCZ) extending from the northern Coral Sea southeast to affect Vanuatu and New Caledonia. The SPCZ continued to be more active than usual over southern French Polynesia. Rainfall was above average at many locations within these convective regions, but more than 200% of average in parts of New Caledonia and southern French Polynesia. Heavy rainfall occurred in many parts of New Caledonia during the passage of tropical cyclone 'Des', the only occurrence in March, which reached storm force as it tracked southeast from 5 through 7 March. Dry, sunny conditions prevailed over northern Fiji, much of Tuvalu, Toakelau and many islands in northern French Polynesia. Rainfall less than 50% of average continued on the Queensland coast of Australia, extending into the western Coral Sea. The month was unusually warm in Fiji, where mean March air temperatures at some sites were at least 1.5°C above average.

ENSO and sea surface temperatures (SST): Based on recent observations in the equatorial Pacific, the likelihood of an El Niño developing this year has increased. The equatorial Pacific Ocean is warmer than average especially near South America, the Southern Oscillation Index became negative this month, and enhanced rainfall has been observed off the west coast of South America near Ecuador. The forecast models show a strong consensus. The last El Niño event occurred in 1997/98. The next few months will be critical to the development of an El Niño episode.

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

Three month outlook: Above average rainfall is likely in Kiribati and Vanuatu, with average to above average totals in New Caledonia, Fiji, Niue and Pitcairn Island. Average to below average rainfall is expected in many areas from the Solomon Islands east to the Marquesas including the Northern Cook Islands and central French Polynesia.

Feature Article: Summary of the year 2001/02 tropical cyclone season

Sources of South Pacific rainfall data


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