Tropical rainfall outlook: June to August 2008
La Niña conditions are still very likely to influence rainfall patterns during this period. A large region of suppressed convection is very likely flanking the equatorial Pacific from Western to Eastern Kiribati, Tuvalu, the Northern Cook Islands, Tuamotu, the SocietyIslands, and the Marquesas. Average rainfall is likely for the Solomon Islands, Pitcairn Island, and Samoa.
Enhanced convection is likely from Papua New Guinea extending southeastward toward Vanuatu, through to the Southern Cook Islands, including New Caledonia, Fiji, Niue, and Tonga. Above average rainfall is expected in those countries for the coming three-month period.
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 June is 62%, 1% lower than the long-term average for all months combined.
| Island group | Rainfall outlook | Outlook confidence |
|---|---|---|
| Vanuatu | 15:25:60 (Above) | Moderate - high |
| Niue | 15:30:55 (Above) | High |
| Tonga | 15:30:55 (Above) | Moderate - high |
| Cook Islands (Southern) | 15:35:50 (Above) | Moderate - high |
| Papua New Guinea | 20:30:50 (Above) | Moderate - high |
| Wallis & Futuna | 20:30:50 (Above) | Moderate - high |
| Fiji | 20:35:45 (Above) | Moderate |
| New Caledonia | 20:35:40 (Above) | Moderate |
| Pitcairn Islands | 30:35:35 (Climatology*) | Moderate |
| Samoa | 30:35:35 (Climatology*) | Moderate |
| Solomon Islands | 30:35:35 (Climatology*) | Moderate |
| Austral Islands | 40:30:30 (Below) | Moderate |
| Society Islands | 45:30:25 (Below) | Moderate |
| Tuamotu Islands | 50:30:20 (Below) | Moderate - high |
| Kiribati (Eastern) | 50:35:10 (Below) | Moderate - high |
| Kiribati (Western) | 50:35:10 (Below) | Moderate - high |
| Marquesas Islands | 60:25:15 (Below) | Moderate - high |
| Tokelau | 60:25:15 (Below) | Moderate - high |
| Cook Islands (Northern) | 60:30:10 (Below) | Moderate - high |
| Tuvalu | 65:25:10 (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.