Tropical rainfall and SST outlook: March to May 2011
During March – May 2011, a region of suppressed convection is likely in the southwest Pacific encompassing...
During March – May 2011, a region of suppressed convection is likely in the southwest Pacific encompassing Tuvalu, Tokelau, Western Kiribati, the Tuamotu Archipelago, the Marquesas 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, Wallis & Futuna, Samoa, and Eastern Kiribati. Enhanced convection is likely along the Southwest Pacific Convergence Zone, which is expected to be displaced to the southwest of normal. Papua New Guinea, New Caledonia, Tonga, and the Austral Islands are expected to receive above normal rainfall for the coming three month period. Near or above average rainfall is forecast for Niue, the Solomon Islands, Vanuatu, Fiji, and the Southern Cook Islands
The ensemble of global models show a weakening of the near equatorial Pacific sea surface temperature cold anomalies in the coming months, and contraction cold waters that exist west of the International Dateline. Above average SSTs are forecast for the Austral Islands and New Caledonia. Average or above average sea surface temperatures are forecast for Papua New Guinea, Vanuatu, Tonga, Fiji, and the Southern Cook Islands. Near normal or below normal SSTs are forecast for Tuvalu, Wallis & Futuna, Western Kiribati, Samoa, the Society Islands, Tokelau, and the Tuamotu Archipelago. Eastern Kiribati, the Northern Cook Islands and the Marquesas are expected to experience below normal SSTs. Near normal SSTs are forecast for Niue, Pitcairn Island and the Solomon Islands.
The forecast confidence for the rainfall outlook is moderately high. The average region–wide hit rate for rainfall forecasts issued in March 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 March to May 2011
SST anomaly outlook map for March to May 2011
NOTE: Rainfall and sea surface termperature estimates for Pacific Islands for the next three months are given in the tables 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.