Weekly Tropical Climate Note
Issued on Tuesday 11 March 2014
Madden-Julian Oscillation in western hemisphere
The Madden-Julian Oscillation (MJO) has progressed into the western hemisphere. The past week has seen active tropical weather over South America while convection remained generally suppressed over the tropical Indian Ocean. When the MJO is over the western hemisphere at this time of year it usually contributes to a break period in the North Australian Monsoon, with higher than normal pressure often observed over the equatorial Indian Ocean and the Maritime Continent including northern Australia.
Despite the MJO contributing to conditions that are unfavourable for large-scale tropical convection over northern Australia, a weak monsoon trough has remained to the north of Australia, over the Coral Sea and the Southwest Pacific during the week. Three tropical cyclones have also developed across these regions: tropical cyclone Hadi currently in the Coral Sea; tropical cyclone Gillian that has now weakened and is situated in the Gulf of Carpentaria; and, tropical cyclone Lusi near Vanuatu. A westward moving, large-scale tropical wave (an Equatorial Rossby wave) has also been active in Australian and far west south Pacific longitudes and is likely to have enhanced tropical cyclone development in these regions.
The MJO is forecast to continue in an eastward progression with some forecast models weakening the MJO by early next week while others maintain a moderate strength for at least the next two weeks. With exception to the hazardous weather in the vicinity of the tropical lows around the far north of Australia and the South Pacific, the rest of the Asia-Pacific tropics are likely to see suppressed convective conditions for the rest of this week and possibly up to two weeks, depending on the strength of the MJO influence.
See the Bureau's MJO Monitoring for more information on location and tracking of the MJO.
ENSO state: neutral, warming expected
The El Niño–Southern Oscillation (ENSO) remains neutral. The 30-day Southern Oscillation Index (SOI) value to 9 March is -6.3. The latest NINO3.4 sea surface temperature anomaly is -0.3 °C.
Climate models forecast Pacific Ocean temperatures to warm in the coming months, approaching El Niño thresholds around the middle of the year. El Niño is often, but not always, associated with below normal rainfall during the second half of the year across large parts of southern and inland eastern Australia.
See the Bureau's ENSO Wrap-Up which includes a compilation of computer model predictions of ENSO indices.
Next update expected by 18 March 2014| Product Code IDCKGEWOOO
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