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Monthly climate

Climate developments in April 2004

Enhanced convection and above average rainfall occurred from the Solomon Islands across to Tuvalu, and from the Northern Cook Islands southeast over northern and central French Polynesia to Pitcairn Island. Rainfall was at least 400% of normal (over 400 mm) in the Marquesas Islands, and at least 200% of normal (over 200 mm) over much of the Society and Tuamotu Islands of French Polynesia, and Tuvlau. The SPCZ (South Pacific Convergence Zone) has moved little since March, generally being located further north and east than usual, extending over these islands. April rainfall exceeded 700 mm in northwestern parts of the Solomon Islands, with Munda recording 270 mm on the 4th and 184 mm on the 10th. Two tropical depressions and a slow moving trough of low pressure affected Fiji during the month, all three events producing high rainfall and floods, resulting in the death of at least 10 people with 10 others missing, and US$ 4 million in damages. Nausori Airport recorded more than 100 mm on both the 8th and 15th. There were 26 days with rainfall at Maopoopo in the Wallis and Futuna Islands.

Suppressed convection with below average rainfall occurred in American Samoa, the Southern Cook Islands, and the Austral Islands of French Polynesia. Rainfall was also below average in parts of New Caledonia. Mean air temperatures were extremely high in the Southern Cook Islands (almost 2°C above average). They were about 0.5°C above average in French Polynesia, and about 0.2°C below average in New Caledonia.

Mean sea-level pressures were generally above average west of the Date Line, and below average in the east, especially over the Southern Cook Islands, resulting in windier than normal conditions in New Caledonia.

Climate extremes in April 2004

Country Location Rainfall (mm) % of average Comments
Tuvalu Nanumea 490 205 Well above average
Tuvalu Nui Island 583 243 Record high
French Polynesia Hiva Hoa, Atuona 414 450 Record high
French Polynesia Tahiti-Faa 237 211 Well above average
French Polynesia Takaroa 355 280 Well above average
Pitcairn Island Pitcairn 217 211 Well above average
New Zealand Raoul Island 208 204 Well above average
New Caledonia Ile Art, Belep 42 24 Well below average
Tonga Fua’amotu Airport 36 23 Well below average
New Caledonia Moue 31 24 Extremely low
French Polynesia Tubai 40 21 Well below average
Country Location Mean Temp (°C) Dep. (°C) Comments
Cook Islands Rarotonga Airport 27.5 +1.9 Record high

Outgoing Long-wave Radiation (OLR) anomalies, in Wm-2 are represented by shaded areas, and rainfall percentage of average, shown by numbers. 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 April 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.