Mature El Niño in the tropical Pacific region

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The 2015 El Niño has continued to strengthen over the past fortnight. The ocean and atmosphere are reinforcing each other, with tropical Pacific Ocean temperatures well above El Niño thresholds, consistently weakened trade winds, and a strongly negative Southern Oscillation Index. Strong coupling of the tropical Pacific Ocean and atmosphere is typical of a mature El Niño, and suggests only a small chance of the event finishing before the end of the year.

All international climate models surveyed by the Bureau of Meteorology indicate the tropical Pacific is likely to warm further, peaking later in the year. Typically, El Niño peaks during the late austral spring or early summer, and weakens

during late summer to autumn.

El Niño is usually associated with below-average winter–spring rainfall over eastern Australia and above-average daytime temperatures over the southern half of the country. However, El Niño is not the only influence on rainfall and temperature; other factors, such as sea surface temperatures to the north of Australia and in the Indian Ocean, also affect Australia's climate.

The Indian Ocean Dipole (IOD) continues to remain neutral. A positive IOD event remains possible, with three of the five international models indicating a positive IOD is likely during spring. The other two models remain neutral.

Next update expected on 1 September 2015 | print version


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