Island Climate Update 28 - January 2003

Tropical cyclone update
By Jim Salinger, Jim Renwick, Stuart Burgess, and Ashmita Gosai, NIWA
'Yolanda' developed over southern Tuvalu on 1 December, and then tracked south, passing east of Fiji on the 4th, and then southeast over southern Tonga on the 5th. Maximum sustained winds reached 74 km/h, with heavy rainfall. Fortunately no damage was caused by this event. 'Zoe' formed on 24th December from a tropical depression near Tuvalu and Fiji’s Rotuma Island, intensifying to tropical cyclone intensity as it tracked west on the 26th.

Forecast validation
Forecast period: October to December 2002
The El Niño related region of enhanced convection over Western and Eastern Kiribati was expected to persist, resulting in continued above average rainfall and above average or average rainfall in Tuvalu, Tokelau and the Marquesas Island. A tendency towards below average rainfall was expected from Papua New Guinea to the Society Islands, including New Caledonia, Vanuatu, Fiji, Tonga, Niue and the Southern Cook Islands.

ENSO and Sea Surface Temperatures
Climate Models show El Niño likely to weaken in the Autumn of 2003
Equatorial Pacific SSTs intensified during December
El Niño-related temperature and wind anomalies in the Equatorial Pacific continue to propagate eastwards in December, as the event came close to maturity. The NINO3 SST anomaly (+1.7°C) is now significantly higher than the NINO4 anomaly (+1.3°C) for the first time in this event. Threemonth (Oct-Dec) means are about +1.5°C and +1.4°C for NINO3 and 4, respectively.

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 28 – 9 January 2003
December’s Climate: The El Niño episode is continuing to affect Southwest Pacific rainfall patterns, with enhanced convection and above average rainfall over Western and Eastern Kiribati, and the Northern Cook Islands, and contrasting areas of suppressed convection and well below average rainfall extending from Papua-New Guinea, southeast to the north of New Caledo

Climate developments in December 2002
El Niño continues to enhance convection over Kiribati
Suppressed convection from Papua New Guinea to the Southern Cook Islands
The SPCZ was displaced further east than average, with enhanced convection from Tuvalu southeast to the Society Islands. This region merged with the Inter-tropical Convergence Zone (ITCZ), which was enhanced over Kiribati, and in the central equatorial Pacific just north of the equator.

Rainfall outlook for January to March 2003
Above average or average rainfall in equatorial latitudes from west to east and Society and Pitcairn Island.
Below average or average rainfall from Vanuatu, New Caledonia, trending east to Niue and the Marquesas Islands.
Mainly average rainfall expected elsewhere.
Enchanced convection in the equatorial Pacific region is expected to continue from January till March 2003, resulting in an increased likelihood of above average rainfall in both Western and Eastern Kiribati and Tokelau.
Rainfall is expected to be average or above average in Tuvalu, Socie

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