Weekly Tropical Climate Note

Issued on Tuesday 16 September 2014

Madden-Julian Oscillation likely to remain weak

Over the past week, tropical activity has generally been focused over the far west and eastern equatorial Pacific Ocean, north of the equator. Typhoon Kalmaegi, currently impacting on Hainan Island and the southeastern coast of China, is expected to continue to move west-northwest and making landfall over northern Vietnam with the next 18 hours. Hurricane activity has also been observed in the east Pacific Ocean this past week with Hurricane Oldie currently impacting on the west coast of Mexico.

A very weak Madden-Julian Oscillation (MJO) signal has been observed over the eastern tropical Pacific Ocean this past week, which may have contributed to the enhanced tropical activity observed recently over that region. Model outlooks of MJO diverge somewhat in likely scenarios, however, common to all models is that any MJO activity is likely to be weak. It is possible that the MJO may act to enhance convection over the Americas and tropical Africa to some extent in the coming week.

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

ENSO and the Indian Ocean Dipole

Despite some warming of the tropical Pacific Ocean over the past month, the El Niño-Southern Oscillation (ENSO) remains neutral. However, models continue to suggest an El Niño remains possible in 2014 (at least a 50% chance). The latest NINO3.4 sea surface temperature anomaly is +0.5 °C. The latest Southern Oscillation Index value is -11.0.

The negative Indian Ocean Dipole (IOD) in the tropical Indian Ocean has shown signs of weakening. The latest weekly index value is −0.3 °C (within the neutral range).  All climate models surveyed by the Bureau indicate the IOD will remain neutral during the austral spring and summer

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

Next update expected by 16 September 2014| Product Code IDCKGEW000

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