Weekly Tropical Climate Note

Issued on Tuesday 25 November 2014

Increased tropical activity over the Indian Ocean

This past week, cloudiness was enhanced over the equatorial Indian Ocean and generally supressed near the equator over South–East Asia and the western Pacific Ocean. This is a typical pattern for an active Madden—Julian Oscillation (MJO) over the Indian Ocean, as is currently the case.

Climate models indicate the MJO will remain active and continue to move eastwards in the coming days, entering the region to the north of Australia by the middle of next week. This means there is likely to be a slow transfer of the focus of tropical activity from the tropical Indian Ocean to the region north of Australia (including much of equatorial South-East Asia and the western Pacific Ocean) with the movement of the MJO. Usually, the MJO passes too far to the north of Australia to impact on Australia's tropical rainfall at this time of year. Some models then indicate the MJO will weaken, while others suggest it will remain active and continue its eastward progression towards the western Pacific Ocean.

See the Bureau's MJO Monitoring for more information.

Tropical Pacific Ocean moves closer to El Niño

The Pacific Ocean has shown renewed signs of El Niño development. International climate models expect this situation to continue, with most models predicting values near or beyond El Niño thresholds for the next two to three months. The latest NINO3.4 sea surface temperature anomaly is +1.1 °C and the 30–day Southern Oscillation Index value to 22 November is −8.5. his is the highest weekly anomaly for NINO3.4 since March 2010.

Regardless of whether or not El Niño fully develops, some El Niño–like impacts remain likely. For northern Australia, this means an increased likelihood of drier than usual conditions over the coming months, including an increased chance of the monsoon commencing later than usual.

See the Bureau's ENSO Wrap up for official El Niño information.

Next update expected by 2 December 2014 | Product Code IDCKGEW000

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