Three-month outlook

Rainfall outlook for November 2001 to January 2002

Average to below average rainfall in the central Pacific from Tuvalu to the Marquesas
Average to above average rainfall in some areas west of the Dateline

The SPCZ is expected to remain south of its normal position east of the Dateline, with slightly enhanced trade winds in the central Pacific, resulting in average to below average rainfall throughout Tuvalu, Eastern Kiribati, the northern Cook Islands, Samoa and the Marquesas islands of French Polynesia. Average to above average rainfall is expected in Papua New Guinea, the Solomons, Vanuatu, and Western Kiribati, with enhanced convection likely in areas west of the Dateline. Average rainfall is likely in most other islands.

Rainfall outlook map for November 2001 to January 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 15:40:45 Average to above average Moderate
Papua New Guinea 20:40:40 Average to above average Low
Vanuatu 20:40:40 Average to above average Low
Western Kiribati 20:40:40 Average to above average Low
New Caledonia 35:40:25 Near average Low
Fiji 25:50:25 Near average Moderate
Tonga 25:40:25 Near average Moderate
Niue 20:45:35 Near average Low
Southern Cook Islands 25:50:25 Near average Moderate
Austral Islands 30:40:30 Near average Low
Society and Tuamotu Islands 30:45:25 Near average Low
Pitcairn Island 35:45:20 Near average Low
Tuvalu 45:45:10 Average to below average Moderate
Tokelau 40:40:20 Average to below average Low
Wallis & Futuna 40:40:20 Average to below average Low
Samoa 45:45:10 Average to below average Low
Marquesas 40:40:20 Average to below average Low
Eastern Kiribati 50:40:10 Below average Moderate
Northern Cook Islands 40:40:20 Below average Low

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.