Tropical Climate Update

Tropical cyclone Blanche impacts northern Australia

Tropical cyclone Blanche was the third tropical cyclone to form in the Australian region in the 2016-17 cyclone season, and the first to make landfall over Australia this season. Blanche made landfall on the far northern Kimberley coast on the morning of Monday 6 March about 150 km west of the Northern Territory/Western Australia border as a category 2 storm. Blanche set a new record for the latest date in a tropical cyclone season that the first cyclone for the season made landfall (reliable satellite records commenced in the 1970s). The previous record was Charlie on 1 March 1988.

Tropical cyclone Blanche was a very small storm, with gales and heavy rainfall generally confined to near the system centre. Blanche invigorated an inactive monsoon trough that was initially to the north of the Australian mainland. As Blanche moved over Australia’s north coast during the past week, the associated trough and its influence were relatively localised. Rainfall totals across northern Australia were mostly moderate – less than 100 mm - and confined to the northern and western coastal regions of the Top End of the Northern Territory, and parts of the western Cape York Peninsula and northern Kimberley region. Point Fawcett, on the Tiwi Islands, recorded the highest rainfall observation during Blanche’s passage with a 24-hour total of 384 mm.

Madden-Julian Oscillation ramps up activity over Indian Ocean

Over this past week, as the Madden-Julian Oscillation (MJO) continued its eastwards progression across the Indian Ocean, an active monsoon trough extended across the Indian Ocean, and intense tropical cyclone Enawo formed near Madagascar. Enawo is the strongest storm to form in the southern hemisphere so far this season (sustained 10-minute mean winds of approximately 195 km/h; equivalent to a category 4 tropical cyclone). It is expected to make landfall today over north-eastern Madagascar with destructive winds and flooding rains. 

The MJO recently moved into the far western Maritime Continent at moderate strength. Typically, an MJO signal in this location at this time of the year would enhance rainfall across northern Australia. However, the MJO is predicted by most international climate models to rapidly weaken in the coming days, and become weak or indiscernible. If the signal weakens as expected, the MJO would likely have no significant effect on rainfall for Australia.

A weak MJO signal would also see the risk of tropical cyclone activity in the Australian region return to the climatological average. Historically, the month of March sees the highest frequency of tropical cyclones in the Australian region.

For more information on the MJO, see the Bureau's current MJO monitoring information.

El Niño WATCH in place

The El Niño-Southern Oscillation (ENSO) currently remains neutral. However, recent changes in both the tropical Pacific Ocean and atmosphere, and climate model outlooks surveyed by the Bureau, suggest the likelihood of El Niño forming in 2017 has risen, shifting the Bureau's ENSO Outlook status to El Niño WATCH. This means the likelihood of El Niño forming in 2017 is approximately 50% (twice the climatological average).

For northern Australia, overnight temperatures are typically cooler than usual during the dry season months of May to September in El Niño years.

See the Bureau’s ENSO Wrap-Up for official El Niño, La Niña and Indian Ocean Dipole information.