Island Climate Update 38 - November 2003

Slightly Higher Risk of Tropical Cyclones for South Pacific Countries near the Date Line
Dr Jim Salinger, Dr Jim Renwick and Stuart Burgess
For some South Pacific countries near the Date Line the chances of tropical cyclone activity are slightly higher than normal for the November 2003 – April 2004 season.
The last few tropical cyclone seasons were relatively ‘quiet’ except last year, with only six occurrences during 2000/01, five in 2001/02, but increasing to ten last season (near the long-term average).

Forecast validation
Forecast period: August to October 2003
Average or above average rainfall was expected from Papua New Guinea east to Tokelau, including Samoa, with above average rainfall forecast for Tokelau and Tuvalu. Average or below average rainfall was expected from Western Kiribati east-southeast to the Marquesas Islands, with below average totals in Eastern Kiribati. Another large region of average or below average rainfall was expected from Vanuatu to the Society Islands, including the Southern Cook Islands, Fiji, Tonga and Niue.

ENSO and Sea Surface Temperatures
Tropical Pacific in a neutral ENSO state
Equatorial SSTs warmed slightly
The tropical Pacific remains essentially in a neutral state with no change in the ENSO indices from last month. Equatorial SST anomalies have risen a little recently, and westerly zonal wind anomalies were evident across the western Equatorial Pacific.
The NINO3 SST anomaly rose slightly to about +0.7°C in October (from +0.3°C in September). NINO4 rose to +0.9°C (from +0.7°C in September).

Climate developments in October 2003
Below average rainfall over much of the Southwest Pacifc
Above average rainfall over parts of Vanuatu and New Caledonia
A region of suppressed convection and generally below average rainfall moved west during October to encompass the Caroline Islands, Nauru, and southern parts of Western Kiribati. Another region of reduced convection moved east, situated over Fiji and Samoa. It was very dry, with 50% or less of average rainfall in parts of Western Kiribati and Fiji.

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 38 – 8 November 2003
October’s climate: Rainfall was below average over much of the Southwest Pacific from the Caroline Islands to Eastern Kiribati, and from the region east of Vanuatu to Samoa, including Fiji.

Rainfall outlook for November 2003 to January 2004
Enhanced convection in Papua New Guinea, the Solomon Islands and Samoa
Average or above average rainfall in parts of French Polynesia
Average or below average rainfall about the Date Line from Vanuatu to Niue
Below average rainfall in Eastern Kiribati and the Marquesas Islands
Enhanced convection in the equatorial western Pacific is likely to result in average or above average rainfall in areas from Papua New Guinea east to the Solomon Islands and Samoa.

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