Tropical rainfall outlook: February to April 2008
La Niña conditions are still very likely to influence rainfall patterns during this period, with a large area of suppressed convection very likely along the equatorial Pacific from Western Kiribati to Eastern Kiribati, including Tuvalu, the Society Islands, the Marquesas, Wallis & Futuna, and the Tuamotu Islands. Near or below average rainfall is likely for the Northern Cook Islands and the SolomonIslands, while average rainfall is likely for Samoa.
Enhanced convection with above average rainfall is likely from Vanuatu through to the Austral Islands, including New Caledonia, while near or above average rainfall is likely in Fiji, Pitcairn Island, Tonga, Niue, and the SouthernCook Islands.
The confidence in the forecast model skill for this seasonal outlook is moderate to high for most Pacific Island countries. In the past, the average region-wide hit rate for forecasts issued in February has been 56%, 5% lower than the long term average for all months combined.
| Island group | Rainfall outlook | Outlook confidence |
|---|---|---|
| Austral Islands | 15:35:50 (Above) | Moderate - high |
| New Caledonia | 20:35:45 (Above) | Moderate |
| Vanuatu | 20:35:45 (Above) | Moderate - high |
| Cook Islands (Southern) | 30:30:40 (Near or Above) | Moderate - high |
| Fiji | 25:35:40 (Near or Above) | Moderate - high |
| Niue | 25:35:40 (Near or Above) | Moderate - high |
| Papua New Guinea | 30:30:40 (Near or Above) | Moderate - high |
| Pitcairn Islands | 30:30:40 (Near or Above) | Moderate |
| Tonga | 30:30:40 (Near or Above) | Moderate - high |
| Samoa | 35:35:30 (Near Average) | Moderate |
| Cook Islands (Northern) | 40:35:25 (Near or Below) | Moderate - high |
| Solomon Islands | 40:30:30 (Near or Below) | Moderate - high |
| Wallis & Futuna | 45:30:25 (Below) | Moderate |
| Marquesas Islands | 50:30:20 (Below) | Moderate |
| Society Islands | 50:30:20 (Below) | Moderate |
| Tuamotu Islands | 55:30:15 (Below) | Moderate |
| Tokelau | 55:30:15 (Below) | Moderate |
| Kiribati (Western) | 55:30:15 (Below) | Moderate |
| Kiribati (Eastern) | 60:25:15 (Below) | Moderate - high |
| Tuvalu | 60:25:15 (Below) | Moderate - high |
NOTE: Rainfall estimates for Pacific Islands for the next three months are given in the table. The tercile probabilities (e.g., 20:30:50) are derived from the interpretation of several global climate models. They correspond to the odds of the observed rainfall being in the lowest (driest) one third of the rainfall distribution, the middle one third, or the highest (wettest) one third of the distribution. On the long-term average, rainfall is equally likely (33% chance) in any tercile.
Tropical cyclones
Three tropical cyclones (TC) affected the South Pacific region in January. TC Elisa formed on January 10th southwest of Nukualofa, Tonga and reached maximum sustained winds of 45 knots on 11 January before dissipating. TC Funa, formed on 16 January and had a much greater impact on the islands. Funa intensified quickly while approaching Fiji, and achieved sustained winds of 105 knots on the 18th, and then subsequently tracked southeast toward Tonga and began weakening on 19 January. TC Gene formed on the 27 January northeast of Fiji and tracked southwest toward New Caledonia, reaching Category 3 strength with maximum sustained winds of 100 knots late on 31 Januarybefore swinging to the southeast. TC Gene has continued to deteriorate along a southeast exit path into the extra-tropics. February and March are normally active months for tropical cyclones, and the moderate La Niña conditions at present will continue to influence tropical cyclones in several parts of the South Pacific region.