Tropical rainfall outlook: November 2005 to January 2006
An area of enhanced convection is expected over the Solomon Islands and the Southern Cook Islands, where rainfall is forecast to be above average.
Another large area of near or above average rainfall is expected from Papua New Guinea east to southeast to Pitcairn Island including Wallis and Futuna, Samoa, Fiji, Tonga, Niue, the Austral Islands, and the Tuamotu Islands.
Near or below average rainfall is forecast for Tuvalu, Tokelau, and the Marquesas Islands. Below average rainfall is expected over Eastern Kiribati.
Near average rainfall is expected for the rest of the region. The skill levels of the forecast models are generally moderate during this time of the year.
| Island group | Rainfall outlook | Outlook confidence |
|---|---|---|
| Solomon Islands | 20:25:55 (Above average) | Moderate |
| Southern Cook Islands | 20:30:50 (Above average) | Moderate |
| Papua New Guinea | 20:40:40 (Near or above average) | Moderate |
| Wallis & Futuna | 20:40:40 (Near or above average) | Moderate |
| Samoa | 20:40:40 (Near or above average) | Moderate |
| Fiji | 20:40:40 (Near or above average) | Moderate |
| Tonga | 20:40:40 (Near or above average) | Moderate |
| Niue | 20:40:40 (Near or above average) | Moderate |
| Austral Islands | 20:40:40 (Near or above average) | Moderate |
| Tuamotu Islands | 20:40:40 (Near or above average) | Low – moderate |
| Pitcairn Island | 15:45:40 (Near or above average) | Moderate |
| Western Kiribati | 35:45:20 (Near average) | Moderate |
| Vanuatu | 25:50:25 (Near average) | Moderate |
| New Caledonia | 35:35:30 (Near average) | Moderate |
| Northern Cook Islands | 35:45:20 (Near average) | Moderate |
| Society Islands | 20:45:35 (Near average) | Low – moderate |
| Tuvalu | 45:40:15 (Near or below average) | Moderate |
| Tokelau | 40:40:20 (Near or below average) | Moderate |
| Marquesas Islands | 40:40:20 (Near or below average) | Low – moderate |
| Eastern Kiribati | 50:30:20 (Below average) | 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.
Forecast validation: August to October 2005
Enhanced convection with average or above average rainfall was expected over Papua New Guinea, the Solomon Islands, Wallis and Futuna, the Northern Cook Islands, and the Marquesas Islands. Suppressed convection with average or below average rainfall was expected over Western and Eastern Kiribati, as well as Fiji, the Southern Cook Islands, and Pitcairn Island. Near average rainfall was expected elsewhere.
Areas of enhanced convection, or above average rainfall, affected Papua New Guinea and northern parts of the Solomon Islands, as well as the region from Fiji east to the Austral Islands, including Samoa, Tonga, and Niue. Suppressed convection or below average rainfall occurred in Vanuatu, Western and Eastern Kiribati, the Northern Cook Islands, and the Marquesas Islands. Rainfall was higher than expected in Fiji, Samoa, Tonga, and Niue, and lower than forecast in Western and Eastern Kiribati, Tokelau, the Northern Cook Islands, and the Marquesas Islands. The overall 'hit' rate for the August-October 2005 rainfall outlook was about 55%.