During February – April 2011, a region of suppressed convection is likely in the southwest Pacific encompassing...
During February – April 2011, a region of suppressed convection is likely in the southwest Pacific encompassing Tuvalu, Tokelau, Eastern Kiribati, Western Kiribati, the Tuamotu Archipelago, and the Northern Cook Islands. Below average rainfall is expected for those island groups. Average or below average rainfall is expected for Pitcairn Island, the Society Islands, Samoa and the Marquesas. Enhanced convection is likely along the Southwest Pacific Convergence Zone, which is expected to be displaced to the southwest of normal. New Caledonia, Fiji, Niue, Tonga, and Vanuatu are expected to receive above normal rainfall for the coming three month period. Near or above average rainfall is forecast for the Austral Islands, Papua New Guinea, and the Southern Cook Islands. Near normal rainfall is forecast for the Solomon Islands and Wallis & Futuna.
The ensemble of global models show negative equatorial Pacific sea surface temperature anomalies in the coming months, but with a weakened equatorial cold SST anomaly from previous months forecasts. Above average SSTs are forecast for New Caledonia, Vanuatu, Fiji, Tonga, and Niue, while near or above average SSTs are forecast for the Southern Cook Islands and the Austral Islands. Near or below normal SSTs are forecast for the Northern Cook Islands, the Tuamotu Archipelago, Tuvalu and Tokelau. Below normal SSTs are anticipated for Western Kiribati, Eastern Kiribati, and the Marquesas. Near normal SSTs are forecast elsewhere.
The forecast confidence for the rainfall outlook is moderately high. The average region–wide hit rate for rainfall forecasts issued in February is 63%, 2% higher than all months combined. The SST forecast confidence is mostly high or moderate-to-high, with uncertainty localised near Eastern Kiribati and the Marquesas.
Rainfall anomaly outlook map for February to April 2011
SST anomaly outlook map for February to April 2011
NOTE: Rainfall and sea surface termperature estimates for Pacific Islands for the next three months are given in the table above. The tercile probabilities (e.g., 20:30:50) are derived from the averages of several global climate models. They correspond to the odds of the observed rainfall or sea surface temperatures being in the lowest one third of the distribution, the middle one third, or the highest one third of the distribution. For the long term average, it is equally likely (33% chance) that conditions in any of the three terciles will occur. *If conditions are climatology, we expect an equal chance of the rainfall being in any tercile.