Island Climate Update 17 - February 2002

Feature article

Tropical Cyclones
Only three tropical cyclones so far
Three tropical cyclones have occurred so far this season. The season although relatively quiet has not been benign due to the devastation caused in northern Tonga by 'Waka' early in January. The usual period of peak tropical cyclone occurrence for the Southwest Pacific continues, with an average of two tropical cyclones in February and two in March for the whole region, in seasons similar to the present. On average, the highest frequencies have occurred over the Coral Sea east to Fiji, including Vanuatu and New Caledonia.

Forecast validation

Forecast validation
Forecast period: November 2001 to January 2002
The SPCZ was expected to remain south of its normal position east of the Dateline, with slightly enhanced trade winds in the central Pacific, resulting in average to below average rainfall throughout Tuvalu, Eastern Kiribati, the northern Cook Islands, Samoa, and the Marquesas Islands of French Polynesia. Average to above average rainfall was expected in Papua New Guinea, the Solomons, Vanuatu, and Western Kiribati, with enhanced convection likely in areas west of the Dateline.

ENSO & SST

ENSO and Sea Surface TEmperatures
Warm seas about and west of the dateline; warm ENSO event possible later this year
SST anomalies remain fairly weak across the Equatorial Pacific, with negative temperature anomalies east of about 150°W and positive anomalies about the dateline (around Kiribati). Sub surface sea temperature observations now show positive anomalies (exceeding +4°C at 150 m depth) in the central Pacific.

February

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 17 – 10 February 2002
January's Climate: Rainfall patterns switched in January, with dry sunny conditions replacing the wet weather of December over much of Kiribati, Tuvalu, Tokelau, Samoa, Tonga, and most of French Polynesia – some sites having record low January rainfall. Rainfall was also well below average along the Queensland coast of Australia and in the Kermadecs.

Monthly climate

Climate developments in January 2002
Low rainfall over Kiribati and islands east of the dateline
January rainfall and OLR anomalies were opposite those recorded in December throughout much of the region. Dry sunny conditions replaced wet weather, with less than 50% of average rainfall, over much of Kiribati, Tuvalu, Tokelau, Samoa, and Tonga. Most stations in French Polynesia measured only 10-40% of average rainfall.

Three-month outlook

Rainfall outlook for February to April 2002
SPCZ More active in the west
Below average rainfall in equatorial latitudes from Kiribati east, mainly average rainfall in other areas; trending towards above average in the Solomons and Fiji.
The SPCZ is likely to be displaced slightly south of its normal location in the west, from February through April, with enhanced trades east of the dateline and weaker trades to the west.

Data sources

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

NIWA