Weather

Weak La Niña peaks; likely to end in autumn

Grain Central, January 18, 2018

A WEAK La Niña pattern continues in the tropical Pacific and is likely to be at or near its peak, with most models suggesting it will end during the southern autumn, according to the Bureau of Meteorology.

La Niña typically brings above average rainfall to eastern Australia during summer, particularly in northern New South Wales and Queensland.

However, a weak La Niña will have less influence on Australian rainfall than a strong event.

La Niña events can also increase the likelihood of prolonged warm spells for southeast Australia.

Sea surface temperatures currently show a clear La Niña pattern, with coolest waters concentrated in the eastern Pacific Ocean.

Likewise, some atmospheric indicators such as trade winds and cloudiness also show a clear La Niña signal.

However, a continuing build-up of warmer water beneath the surface of the western Pacific is a likely precursor to the end of this event.

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, so these thresholds are likely to be met.

The Indian Ocean Dipole (IOD) is currently neutral. IOD events are unable to form between December and April.

Source: BOM

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