Potential for El Nino to return

ACCORDING to the latest Bureau of Meteorology ENSO (El Nino/Southern Oscillation) Wrap-up, sea surface temperatures in the central and eastern Pacific along the equator remain close to El Nino levels.

However, other climate indicators such as the SOI remain in a more neutral pattern.

For example the 30-day average of the SOI as of September 17 was plus 3.3 (up from minus 11 mid-August).

Cloudiness in the central Pacific and strength of the south east trade winds are also more typical of neutral conditions.

This is reflected by the output of international climate models surveyed by the Bureau.

Of the seven models reviewed, four indicate the continuation of a neutral climate pattern through to the end of February 2013, while three indicate the potential development of an El Nino.

Therefore, while a number of models continue to forecast the potential for an El Nino, hopefully any event will be marginal and short term.

It should be noted none of the surveyed climate models suggest a return of La Nina.

Another climate driver that can impact on our climate at this time of year is the Indian Ocean Dipole.

A positive IOD sea surface temperature pattern during May to November is associated with a decrease in rainfall over parts of southern and central Australia (including much of western, central and southern Queensland).

A negative IOD sea surface temperature pattern is associated with an increase in rainfall over southern Australia.

Values of the IOD index have been positive over the past few weeks.

POAMA, the Bureau's climate model, indicates neutral to weakly positive IOD conditions are likely for the remainder of spring.

The ENSO Wrap-up is updated by the Bureau twice a month.

It is available at

The United States Climate Prediction Centre also does a weekly and monthly update of the status of ENSO.

It has issued an El Nino watch alert (defined as conditions being favourable for the development of El Nino within the next six months).

The CPC official forecast indicates a most likely weak El Nino event developing during this month and persisting through December to February 2012/13.

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Topics:  el nino weather

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