MELBOURNE, Australia – Pacific Ocean climate patterns indicate a weak La Niña persists in the tropical Pacific. The event is expected to be short-lived, and end in the southern autumn of 2018, says the latest Enso Wrap-Up from the Bureau of Meteorology (Bom) of the Australian Government.
The latest sea surface temperatures in the central to eastern tropical Pacific remain around La Niña levels (0.8 °C below average), while in the atmosphere, cloud patterns also remain typical of La Niña.
A recent weakening in the trade winds, and a fall in the Southern Oscillation Index (SOI), are likely to be the result of a Madden–Julian Oscillation (MJO) event, and are not considered a signal of an early La Niña breakdown.
However, a build-up of warmer water beneath the surface of the western Pacific may be a precursor to the end of this event in the coming months.
In order for 2017-18 to be classed as a La Niña year, thresholds need to be exceeded for at least three months. Most climate models surveyed by the Bureau suggest this event is likely to last through the southern summer, and decay in the early southern autumn of 2018.
La Niña typically brings above average rainfall to eastern Australia during summer, particularly in northern New South Wales and Queensland.
However, with a weak event expected, this typically means less influence on Australian rainfall. La Niña events can also increase the likelihood of prolonged warm spells for southeast Australia.
The Indian Ocean Dipole (IOD) is currently neutral. IOD events are unable to form between December and April.
