Rainfall outlook for January to March 2002
SPCZ more active than usual Above average to average rainfall in western equatorial latitudes southeast to Samoa, Tonga and Niue: average to below average rainfall in the equatorial east, and from northern Queensland across to Vanuatu
The trade winds are now only slightly enhanced east of the dateline, having weakened to the west with westerly wind anomalies. Thus the SPCZ is now displaced further north of its normal location for the time of year, and is expected to be active during the next few months. Rainfall is projected to be average to above average in equatorial latitudes from Western Kiribati southeast to Tonga and Niue, including Tuvalu, Wallis and Futuna, and Samoa. Average rainfall is expected in Papua-New Guinea, New Caledonia, Fiji, and across southern French Polynesia, to Pitcairn Island. Areas of below average rainfall are likely in Vanuatu, Eastern Kiribati, the Society Islands, and Southern Cooks, with below average rainfall predicted for the Marquesas.
Rainfall outlook for January to March 2002
Probabilities of rainfall departures from average
Broad-scale rainfall patterns and anomalies in the southern tropical Pacific area estimated from the state of large-scale regional climate factors, such as La Niña or El Niño, their effect on the South Pacific and Tropical Convergence Zones, surface and sub-surface sea temperatures, and computer models of the global climate. Rainfall estimates for the next three months for Pacific Islands are given in the adjacent table. The terciles (e.g. 20:30:50) are derived from the interpretation of several global climate models. They correspond to the lowest (driest) one third of the rainfall distribution, the middle one third, and the highest (wettest) one third of the distribution. On the long-term average, rainfall is equally likely (33% chance) in any tercile. The probabilities shown express the expected shift in the distribution from the long-term average, based on predictions of oceanic and atmospheric conditions. The amount of inter-model forecast consistency is indicated by the levels of confidence expressed in the table.
| Island Group | Rainfall Outlook | Confidence in the Outlook | |
|---|---|---|---|
| Solomon Islands | 20:40:40 | Average to Above Average | Moderate |
| Western Kiribati | 20:35:45 | Average to Above Average | Low |
| Tuvalu | 20:35:45 | Average to Above Average | Low |
| Wallis and Futuna | 20:35:45 | Average to Above Average | Low |
| Samoa | 20:35:45 | Average to Above Average | Low |
| Tonga | 10:50:40 | Average to Above Average | Moderate |
| Niue | 20:35:45 | Average to Above Average | Low |
| Papua-New Guinea | 10:60:30 | Near Average | Moderate |
| New Caledonia | 30:40:30 | Near Average | Low |
| Fiji | 10:60:30 | Near Average | Moderate |
| Tokelau | 25:65:10 | Near Average | Moderate |
| Northern Cook Islands | 35:55:10 | Near Average | Moderate |
| Austral Islands | 35:55:10 | Near Average | Moderate |
| Pitcairn Island | 25:65:10 | Near Average | Moderate |
| Vanuatu | 40:40:20 | Average to Below Average | Low |
| Eastern Kiribati | 40:40:20 | Average to Below Average | Moderate |
| Southern Cook Islands | 40:40:20 | Average to Below Average | Low |
| Society & Tuamoto Islands | 40:50:10 | Average to Below Average | Moderate |
| Marquesas | 65:25:15 | Below Average | Moderate |
Rainfall outcomes as estimated from models and historical records. The second column indicates the probability of top (above), middle (average) or bottom (below) tercile rainfall, where a percentage is given. The rainfall outlook is subjectively estimated probability of bottom:middle:top tercile.