Island Climate Update 50 - November 2004

Tropical Cyclone Guidance
Dr Jim Salinger, Dr Jim Renwick, and Stuart Burgess
Higher risk of tropical cyclones for some South Pacific countries near and east of the Date Line this year.
Countries with increased risk over this period are Fiji, Wallis and Futuna, Niue, and the southern Cook Islands, and possibly the Solomon Islands, Tuvalu, Tokelau, Samoa, Tonga, and the Austral Islands of French Polynesia.

Forecast validation
Forecast period: August to October 2004
Enhanced convection was expected with above average rainfall over Eastern and Western Kiribati, and average or above average rainfall in Tuvalu, the Northern and Southern Cook Islands, and the Tuamotu and Austral Islands of French Polynesia. Suppressed convection with average or below average rainfall was expected over Papua New Guinea, Vanuatu, New Caledonia, and Fiji.

ENSO and Sea Surface Temperatures
The tropical Pacific Ocean exhibited a weak El Niño state, but the atmosphere remained uncoupled from the ocean during October. The NINO3.4 average anomaly was +0.9°C again in October (as in September), and +0.8°C for August to September (up from +0.6 in July to September). The subsurface temperature profile shows a region of positive anomalies (+2°C or more) near the surface at the South American coast. Sea surface temperature (SST) anomalies have become positive right across the eastern Equatorial Pacific in the last two weeks.

Climate developments in October 2004
The SPCZ (South Pacific Convergence Zone) was very active over the Solomon Islands, extending east-southeast to Rotuma Island, and across to the region north of Samoa. The enhanced rainfall over the Solomon Islands was caused by a continuation of by cross-equatorial northwesterlies converging with the southern hemisphere trade winds. Enhanced convergence also occurred over Vanuatu.

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 50 – November 2004
October’s climate: The South Pacifc Convergence Zone was very active over the Solomon Islands. Well above average rainfall in parts of Vanuatu and New Caledonia’s Loyalty Islands. Much drier in the main islands of New Caledonia, Fiji and southern Tonga.

Tropical rainfall outlook: November 2004 to January 2005
November heralds the start of the rainy and tropical cyclone season for the South Pacific. Enhanced convection is expected in the equatorial Pacific Ocean where above average rainfall is likely in Western and Eastern Kiribati and Tuvalu. Rainfall is expected to be near or above average over Tokelau and the Northern Cook Islands.
Suppressed rainfall is expected from Papua New Guinea southeast to the Southern Cook Islands, including the Solomon Islands, Fiji, Vanuatu, New Caledonia, Niue and Tonga.

Tropical pacific rainfall - October 2004
Territory and station name
October 2004 rainfall total (mm)
Long-term average (mm)
October 2004 percent of average
Lowest on record (mm)
Highest on record (mm)
Records began
American Samoa
Pago Pago Airport
291.6
254
115
1966
Australia
Cairns Airport
22.0
41
54
0
205
1941
Townsville Airport
7.8
26
30
0
253
1940
Brisbane Airport
42.4
94
45
4
407
1929
Sydney Airport
168.4
78
216
1929
Cook Islands
Rarotonga Airport
41.6
102
41
10
319
1929
Fiji
Rotuma
546.1
340
161
80
656
191

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