Northern Australia is still waiting for the monsoon onset.
The Australian monsoon has not yet arrived for the 2018-19 season. A weak trough north of Australia is likely to persist through the coming week. If the trough moves south over northern Australia in the coming days, it will likely bring showers and possibly storms. The trough is not expected to deepen significantly and Australian Monsoon onset is likely to start building from Sunday the 20th.
Monsoon onset normally occurs in late December around Darwin. Later than normal onsets are often associated with El Niño in the Pacific Ocean. Tropical Pacific Ocean sea surface temperatures exceeded El Niño levels at the end of 2018, but have since receded.
Madden-Julian Oscillation to redevelop over Maritime Continent later this week
The past week saw the Madden-Julian Oscillation (MJO) weaken over the eastern Pacific Ocean. The MJO is currently indiscernible. This means it is unlikely the MJO will influence tropical rainfall at the beginning of this week.
However, climate models indicate the MJO is likely to redevelop over the Maritime Continent later this week. Under these conditions, at this time of year, parts of Australia's tropical north tend to observe above average rainfall, and typically convection is enhanced over South East Asia. It may also provide a favourable environment for monsoon development.
Movement of the MJO
Phases of the MJO
So to sum it up the MJO, is moving back to Phase 3. The MJO is showing the weakening trend but there is an indication of a stronger signal as it moves across the Maritime Continent Phase 4-6, however, conditions are looking brighter for a Monsoonal Surge coming into the last week of January/begin of February
The building of the Westerly Trades coming out of the Maritime area looking encouraging from the 20th, & SSTs are hovering above 28C, even higher in the Melanesia & Polynesian Waters.
Sea Surface Temperatures
Based on Numerical Modelling
Australia Day long weekend looking moderately good for tropical development & some northern ‘wet stuff’ particularly for the Gulf of Carpentaria with possible cyclone development from Friday the 25th through to Saturday the 26th at this stage.
Islands in the Southwest Pacific have signals for the last week in January as well. The signal, especially the OLR, weakens quickly moving out of Phase 6.
So a small window of tropical enhancement or potential from next week. Models, very without solid unity at this early stage, have at least one area of Low Pressure deepening in all 4 zones. However, the Gulf of Carpentaria is the place to watch and then the north-west coast of Western Australia.