Monthly climate

Climate developments in November 2004

The South Pacific Convergence Zone (SPCZ) was active in the region between Papua New Guinea, Nauru and Tuvalu, extending southeast to affect Rotuma Island (northern Fiji), Samoa, Niue, and the Southern Cook Islands. Enhanced rainfall between Papua New Guinea, Nauru and Tuvalu was caused by a continuation of cross-equatorial northwesterlies converging with stronger than normal southeast trade winds. The Inter-Tropical Convergence Zone (ITCZ) was active in the Pacific region (5-10° north of the Equator) about and east of the Date Line. Enhanced convergence also occurred in the region east of Pitcairn Island.

Rainfall was 200% or more of average in some areas of Tuvalu, Rotuma Island, and in some of the Austral Islands. At least 125% of average rainfall occurred in parts of central Tonga.

High 1-day total rainfalls were recorded at Rotuma Island (Fiji) on the 9th (144 mm) and Udu Point (Fiji) on the 11th (140 mm).

A large region of suppressed convection persisted over Southeast Asia, Indonesia, and parts of northern Australia. Other regions of suppressed convection affected parts of Fiji and Tonga, as well as Eastern Kiribati, Tokelau, and the Northern Cook Islands. Rainfall was well below average, being 25% or less of average, in much of New Caledonia and parts of the main island of Fiji, due to frequent ridges of high pressure extending north from the Tasman Sea. It was less than 50% of average in Tokelau, southern Tonga, parts of Samoa, and the Marquesas Islands.

Mean air temperatures were about 1.0°C above average in Western Kiribati, and at least 0.5°C above average in Tuvalu, Samoa, and the Marquesas, Tuamotu, and Society Islands of French Polynesia, consistent with the warm sea surface temperatures affecting these regions. Mean air temperatures were about 0.5°C below average in southern Vanuatu and parts of Tonga.

Mean sea-level pressures were above average about and west of the Date Line in the tropical Southwest Pacific.

Climate extremes in November 2004

Outgoing Long-wave Radiation (OLR) anomalies, in Wm-2 are represented by shaded areas. High radiation levels (yellow) are typically associated with clearer skies and lower rainfall, while cloudy conditions lower the OLR (blue) and typically mean higher rainfalls. The November 2004 position of the South Pacific Convergence Zone (SPCZ), as identified from total rainfall, is indicated by the solid green line. The average position of the SPCZ is identified by the dashed green line. Data source: NOAA-CIRES Climate Diagnostics Center.