Island Climate Update 97 - October 2008

Average annual number of Tropical Cyclones, neutral-ENSO periods, from 1969–70 to 2007–08.
Tropical cyclone risk across the South Pacific, 2008–09
Jim Salinger and James Renwick, NIWA
Neutral El Niño/Southern Oscillation (ENSO) conditions are likely to produce average tropical cyclone activity for most tropical South Pacific countries over the coming months. Communities should remain alert and prepared.
In the South Pacific, tropical cyclones usually develop in the wet season, from November through to April, but occasionally occur in October and May.

Climate developments in September 2008
Outgoing Long-wave Radiation anomalies for September 2008. (Click for enlargement and detail)
The South Pacific Convergence Zone (SPCZ) continued to weaken in September relative to previous months. Only a small region of enhanced rainfall was observed in satellite data during September 2008, centred over Indonesia and Papua New Guinea. A localised region of suppressed convection expanded south of the Equator, and extends from east of the Solomon Islands to Tokelau, and southeast to Tuvalu and Tokelau.

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 97 – October 2008
September’s climate
The South Pacific Convergence Zone (SPCZ) was not as well-defined in September as in previous months.
Very suppressed convection near Western Kiribati and south of the Equator from Nauru to Tuvalu and Tokelau.
Below normal rainfall for many areas in the South Pacific, including Samoa and southwestern French Polynesia.
El Niño/Southern Oscillation (

Tropical rainfall and SST outlook: October to December 2008
Rainfall outlook map for October to December 2008. (Click for enlargement)
Sea surface temperature outlook map for October to December 2008. (Click for enlargement)
During the October–December 2008 forecast period, a region of suppressed convection is likely to encompass the Solomon Islands, and a region extending southeast from Tuvalu to Pitcairn Island, including Tokelau, Wallis & Futuna, Samoa, the Northern Cook Islands, and most of French Polynesia (except the Austral Islands).

Tropical Pacific rainfall - September 2008
Territory and station name
September 2008 rainfall
total (mm)
September 2008 percent
of average
Australia
Cairns Airport
40
111
Townsville Airport
1
5
Brisbane Airport
56
159
Sydney Airport
99
157
Cook Islands
Penrhyn
120
81
Aitutaki
N/A
N/A
Rarotonga Airport
128
118
Fiji
Rotuma Island
215
91
Udu Point
186
164
Nadi Airport
55
78
Nausori
98
59
French Polynesia
Hiva Hoa, Atuona
154
208
Bora Bora
65
100
Tahiti – Faa’a
14
27
Tuamotu, Takaroa
63
77
Gambier, Rikitea
65
48
Tubuai
27
29

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 produced by NIWA and made possible with financial support from the New Zealand Agency for International Development (NZAID), with addi