La Niña conditions continue in the tropical Pacific. However, the event is expected to be short-lived, and is likely to end in the southern autumn of 2018, reports the Australian Government Bureau of Meteorology (BOM) in its latest wrap-up.
Latest sea surface temperature observations in the central and eastern tropical Pacific persist at La Niña levels (0.8 °C below average).
Waters are also cool beneath the surface. While the Southern Oscillation Index (SOI) has eased in the last few days, the SOI has been consistent with La Niña for several weeks. Cloudiness patterns across the Pacific region also show a clear La Niña signal.
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 upon 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.
