Island Climate Update 19 - April 2002

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.

Tropical cyclones
Summary of the year 2001/02 tropical cyclone season
The number of Southwest Pacific tropical cyclones 2001/02 season compared to frequencies during the past 20 years - Click to enlarge
Southwest Pacific tropical cyclone tracks: November 2001 through 31 March 2002 - Click to enlarge
Five tropical cyclones have occurred so far this season, which is the same number as for the whole of last season and well below average (see graph below).

Forecast validation
Forecast period: January to March 2002
The SPCZ was expected to be more active than usual and also further north than average of its normal location. Rainfall was expected to be average to above average in equatorial latitudes from Western Kiribati southeast to Tonga and Niue, including Tuvalu, Wallis and Futuna, and Samoa.Average to below average rainfall was expected in Vanuatu, Eastern Kiribati, the Society Islands, and the Southern Cooks, with below average rainfall in the Marquesas.

ENSO and Sea Surface TEmperatures
Conditions are set for the development of an El Niño
Warmer than average seas across the whole of the tropical Southwest Pacific
The likelihood of an El Niño developing this year, based on recent observations in the equatorial Pacific, has increased. The equatorial Pacific Ocean temperatures are becoming warmer than average especially near South America where anomalies now exceed +1.0°C, The Southern Oscillation Index showed a substantial fall (to -0.8) in March, from weakly positive values over the previous two months.

Climate developments in March 2002
Active convection over equatorial waters about and west of the date line
High rainfall in parts of New Caledonia and southern French Polynesia
Low rainfall from Tuvalu to northern French Polynesia
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 SPCZ extending from the northern Coral Sea southeast to affect Vanuatu and New Caledonia.

Rainfall outlook for April to June 2002
Above average rainfall in Kiribati and Vanuatu
Average to below average rainfall from the Solomon Islands to the Marquesas, including the Northern Cook Islands and central French Polynesia
The South Pacific Convergence Zone moved south in March, lying over Fiji, Tonga and the Southern Cook Islands: displaced further to the southwest than usual in areas west of the dateline. Rainfall is projected to be above average in Western and Eastern Kiribati and Vanuatu, and average to above average in New Caledonia, Fiji, Niue and Pitcairn Island.

Sources of South Pacific rainfall data
This bulletin is a multi-national project with important collaboration from the following Pacific nations:
American Samoa
Australia
Cook Islands
Fiji
French Polynesia
Kiribati
New Caledonia
New Zealand
Niue
Papua New Guinea
Pitcairn Island
Samoa
Solomon Islands
Tokelau
Tonga
Tuvalu
Vanuatu
Requests for Pacific island climate data should be directed to the Meteorological Services concerned.
Acknowledgements
This bulletin is made possible with financial support from the New Zealand Agency for International Development (NZAID), Wellington, New Zealand, wi