The 2011–12 South Pacific cyclone season was one of the least active South Pacific tropical cyclone seasons on record, with only three tropical cyclones occurring during the season. The season ran from November 1, 2011, to April 30, 2012, however, any tropical cyclones that form before June 30, 2012, would have fallen within the 2011–12 tropical cyclone year and would have counted towards the season total. The strongest and only severe tropical cyclone that occurred during the season was Severe Tropical Cyclone Jasmine, which tracked in from out of the South Pacific basin. Within the basin, tropical cyclones are monitored by the Regional Specialized Meteorological Center (RSMC) in Nadi, Fiji, and the Tropical Cyclone Warning Center (TCWC) in Wellington, New Zealand. RSMC Nadi attaches an F designation to tropical disturbances that form in or move into the South Pacific. The United States Joint Typhoon Warning Center (JTWC) issues unofficial warnings within the South Pacific, designating tropical storm-equivalent or greater tropical cyclones with a number and a P suffix. RSMC Nadi and TCWC Wellington both use the Australian Tropical Cyclone Intensity Scale, and measure windspeeds over a period of ten minutes, while the JTWC measures sustained winds over a period of one minute and uses the Saffir–Simpson hurricane scale.
Seasonal forecasts
Ahead of the cyclone season, RSMC Nadi, TCWC Wellington, the Australian Bureau of Meteorology (BoM), the New Zealand National Institute of Water and Atmospheric Research (NIWA) and various other Pacific Meteorological services, all contributed towards the Island Climate Update tropical cyclone outlook that was released in October 2011. The outlook took into account analogue seasons and the La Niña conditions that were developing across the Pacific. The outlook called for a below average number of tropical cyclones for the 2011–12 season, with five to eight named tropical cyclones, to occur between 135°E and 120°W compared to an average of around nine. At least one these cyclones was expected to become either a category 3 or a category 4 severe tropical cyclone, while there was a reduced chance of a Category 5 severe tropical cyclone. In addition to contributing towards the Island Climate Update outlook, RSMC Nadi and the BoM issued their own seasonal forecasts for the South Pacific region.
The BoM issued 2 seasonal forecasts for the South Pacific region between 142.5°E and 120°W, one for the Western Southern Pacific region between 142.5°E and 165°E and one for the Eastern Southern Pacific region between 165°E and 120°W. They noted that the tropical Pacific Ocean was currently experiencing neutral to borderline La Niña conditions which meant that a westward shift in tropical cyclone activity in the basin was favored. As a result, they predicted that the Western South Pacific region was predicted to have 65% chance of being above average, while the Eastern region had a 40% chance of being above average. Within their outlook RSMC Nadi predicted that between five and eight tropical cyclones, would occur within the basin compared to an average of around 9 cyclones. A single tropical cyclone was expected to become or exceed category 3 severe tropical cyclone status. They also reported that the tropical cyclone genesis trough was expected to be located within the Coral Sea. This was based on the expected and predicted ENSO conditions, and the existence of the Pacific warm pool of sub-surface temperature anomalies in this region.
Risk forecasts
Both the Island Climate Update and RSMC Nadi's tropical cyclone outlooks assessed the risk of a tropical cyclone affecting a certain island or territory. As the tropical cyclone genesis trough of low pressure was expected to be located within the Coral Sea, RSMC Nadi predicted that island nations located to the west of the dateline had an elevated chance of above average activity. There was a reduced chance of above average activity for the areas located to the east of the dateline, however, French Polynesia was thought to have an enhanced chance of a tropical cyclone later in the season.
Seasonal summary
Despite predictions of between 5-8 tropical cyclones occurring within the South Pacific Basin, with only two tropical cyclones developing in the basin, while Jasmine moved in from the Australian region. The first tropical disturbance of the season developed on November 13, to the north-east of Fiji and moved south-eastwards before it weakened into an area of low pressure during November 17, as it affected Fiji.