Normal or below normal tropical cyclone (TC) activity is likely for most islands in the southwest Pacific during the remainder of the 2011 – 2012 season.
February through April (the late season) is typically the most active part of the TC season, although some storms have occurred outside of this time frame in the past.
Two tropical cyclones were active during February 2012 (TC Cyril and TC Jasmine), bringing the seasonal total to four. An MJO convective pulse is expected over the maritime continent in late March 2012, which could result in additional TC activity.
On average, nine tropical cyclones occur each year for the southwest Pacific, and are grouped into classes ranging from 1 to 5, with 5 being the most dangerous. For the coming season, at least one cyclone is forecast to reach at least Category 3, with mean wind speeds of at least 64 knots or 118 km/h and one system may reach at least Category 4 strength, with mean wind speeds of at least 86 knots or 159 km/h.
The ICU TC forecast update indicates 8–10 named TCs are likely for whole season, with six to eight named storms forecast for the late season.
Places like Vanuatu and New Caledonia typically experience the greatest TC activity, with an average of about 3 or 4 TCs passing close to those countries each year (see Table, right for late season averages). Near normal to below normal TC activity for the remainder of the 2011–12 season is likely for most islands.
Historical cyclone tracks indicate that TCs can affect parts of southwest French Polynesia, including the Society and Austral Islands, and the southern Cook Islands during La Niñas, especially late in the season. The forecast update indicates extra-tropical trajectories to the south of the Austral Islands and Society Islands are likely during the latter half of the TC season. All islands should remain vigilant as the current La Niña continues to evolve with progression into autumn.
More details about this forecast and the science underpinning it can be found on our website. In the Pacific Islands, consult with your local meteorological service for tropical cyclone guidance as the season progresses.
