Island Climate Update 65 - February 2006

The Southwest Pacific Climate in 2005
Stuart Burgess and Dr Jim Salinger, NIWA
Figure 1. The Southern Oscillation Index (SOI). The index displayed neutral values for the first half of the year then drifted negative into the weak El Niño range for the remainder of the year.
Figure 2: Sea Surface temperature (SST) anomalies (departure from average). Yellow or orange areas represent warmer than average sea surface.
Figure 3.

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 65 – February 2006
January’s climate
Outgoing longwave radiation (OLR) and rainfall anomalies characteristic of weak La Niña conditions – enhanced convection over Indonesia, Papua New Guinea, and northern Australia – suppressed convection in the central equatorial Pacific
Active South Pacific Convergence Zone (SPCZ) further south than average
Above average rainfall in par

Climate developments in January 2006
Outgoing Long-wave Radiation anomalies for January 2006. (Click for enlargement and detail)
A large area of suppressed convection, characteristic of weak La Niña conditions, continued to affect the central equatorial Pacific extending from Nauru to Eastern Kiribati and the Northern Cook Islands.
The SPCZ was quite active, extending from the Solomon Islands towards the Cook Islands, resulting in above average rainfall over parts of American Samoa and Northern Tonga. Near the Date Line, the SPCZ was located further south than average.

Tropical rainfall outlook: February to April 2006.
Rainfall outlook map for February to April 2006. (Click for enlargement)
A large region of enhanced convection is likely from Fiji southeastwards to the Austral Islands, including Tonga, Niue, the Northern and Southern Cook Islands, and the Society Islands.
Suppressed convection is expected over Western and Eastern Kiribati, where rainfall is forecast to be below average.

Tropical cyclone update
There have been three tropical cyclones to date. The first was 'Tam' which occurred north of Viti Levu, Fiji, on 12 January, tracking towards Tonga on the 13th, and then southeast to pass west of Niue, with gale force winds. 'Urmil' was next, on the 15th, with maximum sustained winds of 85 km/h – but well south of Niue. Tropical cyclone 'Jim' was the third occurrence this season, with sustained wind speeds of 150 km/h (hurricane force).

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