Good morning

BOM website does a seasonal outlook
http://www.bom.gov.au/cl...tabs=Further-information


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The tropical cyclone season runs from 1 November to 30 April

About the outlooks

This outlook uses the statistical relationships between tropical cyclone numbers and two indicators: the Southern Oscillation Index (SOI) and the Niño3.4 sea surface temperature anomaly. These two indicators provide a measure of the atmospheric and oceanic state, respectively, of El Niño-Southern Oscillation (ENSO).

The July, August and September SOI and NINO3.4 values were used in making the tropical cyclone season outlook.
Interpreting the outlook

Percentages such as a 60% chance of having more tropical cyclones than average (or a 40% chance of having fewer) mean that for every ten years with similar climate patterns to those currently observed, six years would be expected to have an above-average number of tropical cyclones and four years would be expected to have a below-average number.

The long-term average number of tropical cyclones per season in the Australian region (since 1969–70) is eleven, with four typically making landfall. Since the year 2000, there have been an average of nine tropical cyclones in the Australian region each season.

During El Niño events, there are typically less tropical cyclones than average, while more tend to occur during La Niña events. As always, it is essential that all local communities prepare for the cyclone season regardless of the outlook.


There is also a link to current warning for tropical cyclones
http://www.bom.gov.au/cyclone/

BOM have published the outlook

http://www.bom.gov.au/cl...-onset&tabs2=Outlook

29 August 2019 Next issue 25 June 2020
Late rainfall onset likely for much of northern Australia

The chance of an early northern rainfall onset for the 2019-20 season is low over large parts of northern Australia. Areas which have a less than 30% chance of an early rainfall onset include much of the Top End and central parts of the NT, Cape York Peninsula and eastern Queensland, and the far north Kimberley in WA. In other words, these areas have a greater than 70% chance of a late rainfall onset. Most of northern WA has roughly equal chances of an early or late rainfall onset.

The northern rainfall onset outlook gives an indication of whether the first significant rains after 1 September are likely to be earlier or later than normal.



The El Niño–Southern Oscillation (ENSO) is currently neutral, and forecasts indicate it is likely to remain neutral to at least the end of 2019. This means it is unlikely to be influencing the northern rainfall onset outlook towards either an earlier or later than average onset.

However, waters in the western tropical Pacific Ocean remain warmer than normal, while water temperatures around northern Australia are average to cooler than average. This pattern would typically favour cloud formation away from northern Australia.

The Indian Ocean sea surface temperature pattern remains consistent with a positive Indian Ocean Dipole (IOD). This is expected to persist for the coming months. A positive IOD typically leads to drier than average conditions across northern Australia during the second half of the year. IOD events typically break down in early December, so this driver is unlikely to have a significant influence on rains beyond early December.

The BOM are issuing weekly tropical outlook statements

http://www.bom.gov.au/climate/tropical-note/



Weekly Tropical Climate Note

8 October 2019 Next issue 15 October 2019
Dry start to northern wet season likely for 2019-20

By convention, the northern Australia wet season commences 1 October and runs until 30 April.

Based on recent climate outlooks issued by the Bureau, rainfall across much of northern Australia is highly likely to be below average between now and the end of the year.

The primary climate driver currently influencing the rainfall outlooks over Australia, and the Maritime Continent further north, is the Indian Ocean Dipole (IOD). Currently, the IOD is strongly positive (in fact, the most recent weekly value of +1.94 is the highest on record since at least 2001), and it is likely to remain positive until at least December.

With a positive IOD, rainfall between October and December is typically below average across the Northern Territory and much of northern Queensland. Northern Western Australia (WA) is not significantly influenced by a positive IOD at this time of the year, and so the rainfall outlooks suggest there is about a 50% chance of observing above-average rainfall over the next three months.

Climate models also predict that waters off the northern WA coast will warm in the coming months, and this would likely increase the probability of enhanced rainfall across coastal northern WA.

While rainfall over northern Australia and the Maritime Continent is typically reduced during a positive IOD, it usually contributes to enhanced rainfall across the northwest Indian Ocean and over the Indian subcontinent. It is likely that the above-average cumulative rainfall India observed during the 2019 monsoon season (June to September) is associated with the positive IOD. By October, the Indian monsoon is typically in retreat mode and tracking southwards and weakening. However, the monsoon remains active across India and has yet to commence its annual withdrawal, which typically starts in northern India from early September (further information from the UK Met Office here).
Madden–Julian Oscillation to rapidly weaken

A pulse of the Madden–Julian Oscillation (MJO) over the western Indian Ocean is expected to weaken rapidly in the coming days and become indiscernible.

The rapid weakening of the MJO is likely related to the strong positive Indian Ocean Dipole. The strengthened easterly winds which become established over the Indian Ocean with a positive IOD typically weaken the MJO as it progresses into the eastern tropical Indian Ocean. As a result, it is unlikely that a strong pulse of the MJO will influence the eastern Indian Ocean, including northern Australia and the Maritime Continent, until the IOD has weakened significantly. This also implies that there is a low likelihood of enhanced rainfall due to MJO activity over the Australian tropics, and further north, until late in 2019.

Read more about the Bureau's MJO monitoring.