Madden-Julian Oscillation (MJO)
The Madden-Julian Oscillation (MJO) is the major fluctuation in tropical weather on weekly to monthly timescales. The MJO can be characterised as an eastward moving 'pulse' of cloud and rainfall near the equator that typically recurs every 30 to 60 days.
Read more: About the MJO
MJO phase diagram
*Note: There are missing satellite observations from 16/3/1978 to 31/12/1978.
The MJO phase diagram illustrates the progression of the MJO through different phases, which generally coincide with locations along the equator around the globe. RMM1 and RMM2 are mathematical methods that combine cloud amount and winds at upper and lower levels of the atmosphere to provide a measure of the strength and location of the MJO. When the index is within the centre circle the MJO is considered weak, meaning it is difficult to discern using the RMM methods. Outside of this circle the index is stronger and will usually move in an anti-clockwise direction as the MJO moves from west to east. For convenience, we define 8 different MJO phases in this diagram.
Download data: RMM Data Postscript: RMM 40 days | RMM 90 days
Average weekly rainfall probabilities
These maps show average weekly rainfall probabilities and expected 850 hPa (approximately 1.5 km above sea level) wind anomalies for each of the 8 MJO phases. Green and blue shading indicates higher than normal rainfall would be expected, while red and orange shading indicates lower than normal rainfall would be expected. The direction and length of the arrows indicate the direction and strength of the wind anomaly. The darker the arrow, the more reliable the information is. The relationship of the MJO with Australian rainfall and winds changes with the season (which can be selected at the top).
Print (PDF): JFM | FMA | MAM | AMJ | MJJ | JJA | JAS | ASO | SON | OND | NDJ | DJF
Average outgoing longwave radiation (OLR)
Outgoing longwave radiation (OLR) is often used as a way to identify tall, thick, convective rain clouds. These maps show the difference from expected cloudiness based on the position of the MJO. The violet and blue shading indicates higher than normal, active or enhanced tropical weather, while orange shading indicates lower than normal cloud or suppressed conditions. The direction and length of the arrows indicate the direction and strength of the wind anomaly. The darker the arrow, the more reliable the information is. The relationship of the MJO with tropical weather patterns changes with the season (which can be selected above the maps).
Print (PDF): JFM | FMA | MAM | AMJ | MJJ | JJA | JAS | ASO | SON | OND | NDJ | DJF
Global maps of outgoing longwave radiation (OLR)
Global maps of outgoing longwave radiation (OLR) highlight regions experiencing more or less cloudiness. The top panel is the total OLR in Watts per square metre (W/m²) and the bottom panel is the anomaly (current minus the 1979-1998 climate average), in W/m². In the bottom panel, negative values (blue shading) represent above normal cloudiness while positive values (brown shading) represent below normal cloudiness.
Postscript: 1 day | 3 days | 7 days | 3 months | 6 months | 1 year
Regional maps of outgoing longwave radiation (OLR)
Below: OLR totals over the dateline
The graphs linked to this map show the OLRs for the different regions within the Darwin RSMC area. The horizontal dashed line represents what is normal for that time of year (based on the 1979 to 1998 period). The coloured curve is the 3-day moving average OLR in W/m². Below normal OLR indicates cloudier than normal conditions in this particular area, and is shown in blue shading. Above normal OLR indicates less cloudy conditions and is shown in yellow shading.
Postscript: Coral Sea Dateline Fiji Guam & Marianas Indochina Malyasia & Indonesia Micronesia Nauru & Tuvalu New Guinea Northern Australia Philippines Solomon Island Southern India & Sri Lanka Vanuatu
Daily averaged OLR anomalies
Westerly wind anomalies
Time-longitude plots of daily averaged OLR anomalies (left) and 850 hPa (approximately 1.5 km above sea level) westerly wind anomalies (right) are useful for indicating the movement of the MJO.
How to read the Time-Longitude plots
The vertical axis represents time with the most distant past on the top and becoming more recent as you move down the chart. The Horizontal axis represents longitude.
Eastward movement of a strong MJO event would be seen as a diagonal line of violet (downward from left to right) in the OLR diagram, and a corresponding diagonal line of purple in the wind diagram. These diagonal lines would most likely fall between 60°E and 150°E and they would be repeated nearly every 1 to 2 months.
Tropical low develops but monsoon not expected for northern Australia
A developing tropical low just south of Papua New Guinea has a moderate chance of reaching tropical cyclone intensity in Australia's Eastern Region later this week. Early forecasts suggest it is likely to move away from Australia as it develops further, and not directly influence the Australian mainland during its lifetime.
See the latest information and warnings for Australian tropical cyclones
The latest computer models have no indication of a monsoon trough, and potential widespread rainfall, developing near northern Australia in the coming week, despite the presence of this tropical low. However, the latest rainfall outlook issued by the Bureau indicates a high likelihood of above-average rainfall across much of Australia in the coming weeks. Other international climate outlooks do not indicate as high a likelihood of rain as the Bureau. Currently, the non-Bureau outlooks are generally indicating near-average rainfall for northern Australia in the next two to three weeks.
Madden–Julian Oscillation in Australian region forecast to weaken
A moderately strong pulse of the Madden–Julian Oscillation (MJO) is currently tracking over the western Maritime Continent, approaching Australian longitudes. The influence on rainfall patterns for tropical Australia is typically not significant in this scenario, however rainfall is usually enhanced when an MJO pulse moves into the eastern Maritime Continent. While climate models forecast the MJO pulse to move into this region in the coming days, they also forecast the strength of the MJO to weaken and become indiscernible shortly after entering the eastern Maritime Continent. In this scenario, the influence on rainfall for northern Australia could be expected to be short-lived or insignificant.
Despite the MJO contributing to the development of a monsoon trough over the Indian Ocean during the past week, it appears unlikely that development of monsoonal conditions will occur closer to Australia. There are also no indications of other atmospheric tropical waves which could influence northern Australia's weather in the coming week.
Read more about the Madden–Julian Oscillation
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ACKNOWLEDGEMENT: Interpolated OLR data provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA.
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