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 in the ICU forecast region during December 2011 (TC Fina and TC Grant), and two are currently active in the southwest Pacific basin at the time this ICU issue was released.
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 at on our website. In the Pacific Islands, consult with your local meteorological service for tropical cyclone guidance as the season progresses.
