Weekly Tropical Climate Note
Monsoon finally becomes established over northern Australia
Monsoonal flow has become established over much of northern Australia, as the monsoon trough moved south over the Australian mainland. While relatively weak (based on low-level wind speed), the monsoonal conditions have generated significant rainfall in parts of far northern Australia from the Kimberley region of Western Australia, across to Cape York Peninsula in Queensland. The largest rainfall totals recorded in recent days have been in the Northern Territory, associated with the monsoon trough and embedded slow-moving tropical low currently located near the base of the Territory's Top End. Several coastal locations in the Top End's north and east have observed daily rainfall totals in excess of 150 mm, and event totals of more than 500 mm (Bing Bong Port on the southwest Gulf of Carpentaria coast had recorded over 600 mm to 9am 23 January). There is variation among forecast models on the location and strength of the tropical low over the coming days.
The largest rainfall totals during the current monsoon burst are likely to be associated with tropical lows in the monsoon trough. Some models indicate the eastern Top End and western Gulf of Carpentaria will remain the favoured regions for any tropical lows, while others suggest the western Northern Territory or Kimberley region will be the focus for tropical low development in the coming days. Models also indicate the monsoon trough will extend into the Coral Sea later in the week, increasing rainfall over Cape York Peninsula and raising the potential of a tropical low forming in the Queensland region. In all regions, there is a heightened risk of tropical cyclone formation with any tropical low that moves over open water.
For up-to-date information on tropical cyclones in the Australian region, visit the Bureau's Current Tropical Cyclones webpage.
Madden–Julian Oscillation over the Maritime Continent
A moderate to strong pulse of the Madden–Julian Oscillation (MJO) lies over the western Maritime Continent. Climate models generally agree the MJO signal will maintain its strength, or weaken marginally, and track eastwards over the coming week. At this time of the year, the MJO over the Maritime Continent is typically associated with increased cloudiness and rainfall over northern Australia. Historically, the effect on rainfall for northern Australia peaks as the MJO moves over the eastern Maritime Continent. A broadscale westerly wind flow is typically established over northern Australia and the southern Maritime Continent in this scenario. This means the current monsoon conditions will likely continue; with widespread, enhanced rainfall for northern Australia in the coming week.
See the Bureau's current MJO monitoring for more information.
Weak La Niña in the tropical Pacific Ocean
A weak La Niña pattern continues in the tropical Pacific. Most models suggest this La Niña will end during the southern autumn.
La Niña typically brings above-average rainfall to eastern Australia, including northern Queensland, during the first few months of the year. However, a weak La Niña will have less influence on Australian rainfall than a strong event.
See the Bureau's current ENSO Wrap-Up for more information.
Product code: IDCKGEW000