Island Climate Update 36 - September 2003

Information on Drought
Stuart Burgess and Ashmita Gosai, NIWA Climate Applications and Research Group
The issue of drought can be a major concern in some Southwest Pacific countries. Drought occurs during a sustained period of low rainfall, which has persisted long enough to produce serious hydrological imbalances.

Forecast validation
Forecast period: June to August 2003
Normal or above normal rainfall was expected from Papua New-Guinea east-southeast to the Society Islands of French Polynesia. Average or below normal rainfall was forecast for the Marquesas Islands. Near normal rainfall was expected elsewhere.
Rainfall was below normal in an extensive region along the equator from west of the Caroline Islands to the region northeast of the Marquesas Islands, and also from the Coral Sea southeast to the region south of Tonga.

ENSO and Sea Surface Temperatures
Neutral ENSO state in the tropical Pacific Ocean
Weaker tradewinds in western equatorial Pacific
The Equatorial Pacific atmosphere and ocean remains in a neutral state. The equatorial sea surface temperature (SST) anomalies are generally positive across the Pacific. The NINO3 SST anomaly weakened slightly to +0.3°C in August (from +0.4°C in July), and NINO4 is about +0.7°C. The three month (June – August) means were +0.1°C and +0.6°C for NINO3 and NINO4, respectively.

Climate developments in August 2003
Extremely dry in New Caledonia and Vanuatu
A large area of suppressed convection occurred from the Solomon Islands southward to include Vanuatu and New Caledonia, and eastward to encompass Western Kiribati, Rawaki, and Tokelau. Many sites in these areas recorded less than 25% of their normal August rainfall, especially Vanuatu and northern areas of New Caledonia where it was extremely dry and some gauges recorded totals below 10 mm.

Rainfall outlook for September to November 2003
Normal or above normal rainfall is expected in Papua New Guinea and the Austral Islands
Normal or below normal rainfall in the equatorial region and Tuvalu, Fiji, and the Tuamotu and Marquesas Islands
Neutral ENSO conditions suggest a near normal rainfall pattern over many countries in the region.

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 36 – 8 September 2003
August’s climate: A large area of suppressed convection occurred from the Solomon Islands southward to include Vanuatu and New Caledonia, and eastward to encompass Western Kiribati, Rawaki, and Tokelau.

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