Tropical rainfall outlook: May to July 2008
La Niña conditions are still very likely to influence rainfall patterns during this period. A large area of suppressed convection is very likely along the equatorial Pacific from Western Kiribati to Eastern Kiribati, including Tuvalu, the Northern Cook Islands, Tuamotu, and the Marquesas Islands. Near average rainfall is likely for the Solomon Islands and Samoa., while normal to above normal rainfall is likely for Pitcairn Island and the Society Islands.
Enhanced convection is likely from Papua New Guinea extending southeast to Vanuatu through to the Austral Islands of French Polynesia, including New Caledonia, Fiji, Tonga, the Southern Cook Islands, and Niue, which are expected to receive near or above average rainfall.
The confidence in the forecast model skill for this seasonal outlook is moderate to moderately high for most Pacific Island countries. In the past, the average region-wide hit rate for forecasts issued in April is 52%, 8% lower than the long-term average for all months combined.
| Island group | Rainfall outlook | Outlook confidence |
|---|---|---|
| Vanuatu | 10:25:65 (Above) | Moderate - high |
| Papua New Guinea | 15:30:55 (Above) | Moderate |
| Tonga | 15:30:55 (Above) | Moderate - high |
| Fiji | 15:35:50 (Above) | Moderate - high |
| New Caledonia | 15:35:50 (Above) | Moderate |
| Niue | 15:35:50 (Above) | Moderate - high |
| Austral Islands | 20:30:50 (Above) | Moderate - high |
| Cook Islands (Southern) | 25:30:45 (Above) | Moderate - high |
| Society Islands | 25:35:40 (Near or Above) | Moderate |
| Wallis & Futuna | 25:35:40 (Near or Above) | Moderate - high |
| Pitcairn Islands | 25:40:35 (Near or Above) | Moderate - high |
| Samoa | 30:35:35 (Near normal) | Moderate |
| Solomon Islands | 30:35:35 (Near normal) | Moderate |
| Tuamotu Islands | 45:30:25 (Below) | Moderate |
| Kiribati (Eastern) | 45:35:20 (Below) | Moderate |
| Kiribati (Western) | 45:35:20 (Below) | Moderate |
| Cook Islands (Northern) | 50:30:15 (Below) | Moderate |
| Tokelau | 50:30:15 (Below) | Moderate |
| Marquesas Islands | 60:25:15 (Below) | Moderate - high |
| Tuvalu | 65:20:15 (Below) | Moderate |
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.