Tuesday 09 August 2022

La Niña Watch continues: likelihood of La Niña around 50% in late 2020, says Bom

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MELBOURNE, Australia – Both the El Niño–Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) remain neutral, according to the Bureau of Meteorology of the Australian Government. The Bureau’s ENSO Outlook is at La Niña WATCH, indicating the chance of La Niña forming in 2020 is around 50%—roughly double the average likelihood.

The surface and sub-surface of the tropical Pacific Ocean have cooled over recent months. While the cooling trend has eased compared to two weeks ago, over half of the surveyed international climate models anticipate this cooling will approach or exceed the threshold for La Niña during spring.

Other ENSO indicators, such as the Southern Oscillation Index (SOI), trade winds, and cloudiness near the Date Line, are also consistent with a neutral ENSO state.

Much of the eastern Indian Ocean remains warmer than average; three of six models continue to suggest the possibility of a negative IOD developing by early spring. Most models show a broad spread of likely scenarios between the neutral and negative IOD range.

Both La Niña and negative IOD typically increase the chance of above average rainfall across much of Australia during spring.

The Southern Annular Mode (SAM) is neutral and is expected to remain so for the next fortnight.

The Madden–Julian Oscillation (MJO) is not currently having any widespread influence on rainfall patterns across northern Australia, though it is contributing to stronger than average easterly flow across parts of northern Australia.

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