Tropical rainfall outlook: December 2007 to February 2008
Typical La Niña rainfall patterns are very likely to continue with a large area of suppressed convection along the equator from Kiribati, including Tuvalu, Tokelau, the Northern Cook Islands, and the Marquesas, Tuamotu,and Society Islands.
Near or below average rainfall is expected for Pitcairn Island.
Enhanced convection is likely to continue along a SPCZ displaced southwest, from the Solomon Islands through to the Austral Islands in French Polynesia. Included in the above average rainfall are Vanuatu, Wallis & Futuna, Tonga, Niue, and the Southern Cook Islands. Near or above average rainfall is expected in Papua New Guinea, New Caledonia, Fiji, and Samoa.
The confidence in the forecast model skill for this seasonal outlook is moderate to high for all Pacific Island countries. In the past, the average region-wide hit rate for forecasts issued in November has been 66%, 6% higher than the long term average for all months combined.
| Island group | Rainfall outlook | Outlook confidence |
|---|---|---|
| Tonga | 20:25:55 (Above) | High |
| Niue | 20:25:55 (Above) | High |
| Vanuatu | 20:30:50 (Above) | High |
| Southern Cook Islands | 20:30:50 (Above) | High |
| Solomon Islands | 25:30:45 (Above) | High |
| Wallis & Futuna | 20:35:45 (Above) | High |
| Austral Islands | 20:35:45 (Above) | High |
| Papua New Guinea | 20:40:40 (Near or above) | Moderate - high |
| New Caledonia | 20:40:40 (Near or above) | Moderate-high |
| Fiji | 20:40:40 (Near or above) | Moderate - high |
| Samoa | 20:40:40 (Near or above) | Moderate - high |
| Pitcairn Islands | 40:40:20 (Near or below) | Moderate - high |
| Society Islands | 40:35:25 (Below) | Moderate |
| Tokelau | 45:30:25 (Below) | High |
| Northern Cook Islands | 45:30:25 (Below) | High |
| Tuamotu Islands | 45:30:25 (Below) | High |
| Tuvalu | 50:30:20 (Below) | High |
| Marquesas Islands | 55:25:20 (Below) | High |
| Western Kiribati | 60:25:15 (Below) | High |
| Eastern Kiribati | 50:30:20 (Below) | 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
Tropical cyclone Guba, the first this season, occurred just over and south of Papua New Guinea between 13–19November, with estimated maximum sustained wind speeds on 16 November of 139 km/h (category 1 on the Saffir-Simpson scale). Severe flooding was reported in parts of Papua New Guinea.
The La Niña conditions presently affecting the Pacific are still likely to influence tropical cyclones in several parts of the South Pacific this season, with a lower rate of occurrence expected in islands east of the Date Line, but with variablerisk elsewhere; all islands should remain vigilant.