Global setting: November 2016
The tropical Pacific exhibits mainly neutral ENSO (El Niño-Southern Oscillation) conditions.
Sea surface temperatures (SSTs) in the central Equatorial Pacific Ocean are marginally below average and do not exceed the threshold used by NOAA’s Climate Prediction Center to define La Niña events. Additionally, sub-surface temperatures in the central and eastern Pacific Ocean (150°W to 110°W) have continued to warm, a signal from the ocean that La Niña conditions are easing. The atmospheric setup is mixed, as stronger easterly trade winds in the western Pacific along with enhanced convection north and east of Papua New Guinea are consistent with weak La Niña conditions. However, the Southern Oscillation Index (SOI) remains weakly negative and is consistent with ENSO-neutral conditions.
International guidance still slightly favours La Niña conditions (53% chance) over the next three month period (December 2016 - February 2017). However, neutral conditions are much more likely than La Niña by March - May 2017: 80% chance for neutral, and only 16% for La Niña. In summary, La Niña conditions are only slightly more likely than not over the next 3-month period, and become significantly less likely as we progress into 2017.
Consequently, the combination of easing La Nina conditions, along with the absence of other large-scale climate drivers this summer, results in no clear air flow anomaly. Typical summer conditions are expected of anticyclones crossing the North Island and prevailing westerly winds over the South Island.
Sea Surface Temperatures
Sea surface temperatures around New Zealand are expected to be near average or above average over the next three months.