Weekly Tropical Climate Note

TC Oma skirts New Caledonia

Category 3, severe tropical cyclone Oma formed north of Vanuatu on 12 February and is currently located to the northwest of New Caledonia, in the eastern Coral Sea. For the coming days, Oma is forecast to move relatively slowly to the south-southwest over the Coral Sea and maintain a similar intensity. There are warnings current for damaging wind, heavy rains and dangerous seas for parts of the southwest Pacific.

For the latest warnings and information on TC Oma go to the  Fiji Meteorological Service.

As Oma moves closer to the Australian mainland, the very large ocean swells it has generated are expected to lead to hazardous surf and abnormally high tides about the central and southern Queensland and far northern New South Wales coasts this week.

Keep up to date with the latest warnings issued by the Bureau.

Oma developed from a tropical low which was embedded in the monsoon trough which was responsible for generating the very heavy rainfall and major flooding recently observed over northern Queensland.  

Read more about the recent Queensland floods.

Madden–Julian Oscillation triggers monsoon break

A pulse of the Madden–Julian Oscillation (MJO) continued to track eastwards across the western Pacific Ocean during the past week before emerging over African longitudes. At this time of the year, an MJO pulse near Africa typically leads to suppressed rainfall over the broader Australian and Maritime Continent region. Climate models indicate the MJO pulse will stall or move slowly east in the coming week, remaining well away from the Australian region for the next fortnight. As a result, the current location of the MJO will help to maintain suppressed rainfall conditions across northern Australia throughout this period.

The Australian Monsoon, which was very active at the start of February, has completely dissipated, leading to monsoon break conditions across the region. During a monsoon break, rainfall may still be prevalent across the tropics, but is generally associated with isolated showers and thunderstorms as opposed to widespread rainfall over lengthy periods.

A separate tropical wave, called an equatorial Rossby wave, may act to counter some of the suppressing rainfall influence of the MJO in the coming days. A Rossby wave, which typically moves westward, currently lies to the east of Papua New Guinea, as evidenced by the pair of tropical lows straddling the equator. In this case, the southern hemisphere low is tropical cyclone Oma; the tropical low in the northern hemisphere is rated as having a high chance of developing to tropical cyclone intensity in the next 24 hours. Climate models suggest the Rossby wave will weaken as it approaches Maritime Continent longitudes, but the influence of the Rossby wave might lead to areas of enhanced rainfall in the eastern Maritime Continent over the next few days. There is not likely to be any enhanced rainfall associated with this tropical wave across northern Australia in the coming week.

Read more about the Bureau's current MJO monitoring.