Weekly Tropical Climate Note
Late wet season tropical activity for northern Australia
A monsoon trough is expected to develop across the Indonesian archipelago and Arafura Sea this week. While the monsoon trough is not expected to extend as far south as Australia, some associated rainfall is likely to fall across parts of Australia's far north in the coming week. This is late in the season for this to happen, as dry season conditions are typically becoming established at this time of the year. With an active monsoon trough developing there is also an increased risk of tropical low or cyclone development in Australian waters, though current weather models do not indicate tropical cyclone formation in the Australian region in the coming week.
Keep up to date with tropical cyclone outlooks and advices at the Bureau's Current Tropical Cyclones page.
Madden–Julian Oscillation triggers monsoonal conditions to the north of Australia
The forecast monsoonal conditions across Indonesia and the Arafura Sea are primarily due to a moderate to strong pulse of the Madden–Julian Oscillation (MJO) which has tracked eastwards across the Indian Ocean during the last fortnight. The MJO is forecast to maintain its strength as it tracks further east across the Maritime Continent in the coming week. With the MJO over this region at this time of the year, enhanced rainfall is typically observed across the near-equatorial region to Australia's north as well as the far northern Australian mainland.
The active phase of the monsoon is unlikely to be a protracted event in this instance as the MJO is forecast to weaken significantly in about a week. Being so late in the northern Australian wet season, the influence of the MJO on Australian climate is diminished, so a return to a transition to dry season conditions is likely to rapidly resume in its wake.
Read more about the Bureau's current MJO monitoring.
Unprecedented tropical cyclone activity in southwest Indian Ocean
Less than a month since tropical cyclone Idai made landfall on the central Mozambique coast as one of the most destructive tropical cyclones to affect the southern hemisphere, in terms of impacts, another intense tropical cyclone, Kenneth, made a direct hit on the southern African country. Kenneth was the first tropical cyclone on record to make landfall on the northern coast of Mozambique and was also the most intense tropical cyclone to make landfall on Mozambique in recorded history. Kenneth was the equivalent of a category 4 tropical cyclone on the Australian scale, with sustained winds to 200 km/h, when it made landfall on 25 April. Many fatalities have been reported, along with widespread damage to infrastructure, vegetation and crops. Kenneth generated very heavy rainfall, in excess of 500 mm in some locations, and caused significant, widespread flooding.
Another weaker system, ex-tropical cyclone Lorna, which peaked at an intensity comparable to an Australian category 3 system, dissipated over the central southern Indian Ocean in the past 24 hours, just west of the Australian tropical cyclone region. This system remained over open water throughout its entire life cycle.
With the addition of Lorna, the 2018-19 cyclone season for the southwest Indian Ocean has seen a total of 16 storms, the highest number on record (previous record was 15 storms in 1993-94).
Product code: IDCKGEW000