Weekly Tropical Climate Note

Issued on Tuesday 26 August 2014

Tropical variability

Over the past week, tropical activity has been focussed over the central equatorial Indian Ocean and the tropical central and eastern Pacific Ocean. Warmer than normal sea surface temperatures have been fuelling two tropical storms in the eastern equatorial Pacific Ocean, hurricane Marie and tropical storm Karina. The activity over the Indian Ocean has been present for almost three weeks now, and may be related to a relatively weak Madden–Julian Oscillation (MJO) event that has been analysed in the region over this period.

Most climate models predict the MJO signal over the Indian Ocean will weaken in the coming days, and hence is not likely to influence tropical weather. However, one model indicates the MJO will maintain strength while moving slowly eastwards across the tropical Indian Ocean over the coming week. If the MJO maintains strength it is possible that it will act to enhance tropical activity in the eastern Indian Ocean and then South–East Asia towards the end of the week. Tropical activity is often suppressed over the northwest Pacific when there is an MJO signal over the Indian Ocean.

See the Bureau's MJO Monitoring for more information on location and tracking of the MJO.

ENSO and Indian Ocean Dipole

While the tropical Pacific Ocean temperatures remain at neutral levels, there is still a chance of an El Niño in 2014. The latestNINO3.4NINO3.4 sea surface temperature anomaly is +0.3 °C. The latest 30–day Southern Oscillation Index (SOI) value up to 24 August is −9.3.

A negativeIndian Ocean Dipole (IOD) pattern remains in place over the tropical Indian Ocean. The latest value of the IOD index is −0.5 °C. A negative IOD pattern typically brings wetter conditions to inland and southern Australia during winter and spring, but its influence usually ends before summer begins. Model forecasts expect this negative IOD event to decay within the next month.

See the Bureau of Meteorology's ENSO Wrap up for official El Niño information including computer model projections.

Next update expected by 2 September 2014| Product Code IDCKGEW000

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