THE CLIMATE KELPIE BLOG: What’s predicted in October?
The Bureau of Meteorology on Tuesday 29th September announced that we have now hit the thresholds for a La Niña. This has been driven by the temperatures in the central Pacific Ocean continuing to cool and the stronger than normal trade winds. It is therefore likely that ‘Above Average’ rainfall could be recorded across much of Australia over the coming months. The Indian Ocean is also still looking favourable to help deliver increased rainfall in mid-late Spring with temperatures in this ocean continuing to warm which could result in the formation of a negative Indian Ocean Dipole (IOD) during October and continuing into November.
As a result, the overall outlook for the last three months of 2020 is for ‘Above Average’ rainfall across the eastern two thirds of Australia. For temperature, maximums are likely to be ‘Above Average’ across much of northern Australia, the southern regions of Victoria and all of Tasmania, with most other regions having an equal chance of ‘Above’ or ‘Below Average’. Minimums are likely to be ‘Above Average’ for most of Australia except for a small area in the south west of Western Australia where there are equal chances of minimum temperatures being ‘Above’ or ‘Below Average’.
In September, much of the centre third of Australia received ‘Above Average’ rainfall (Fig. 1). However, there were regions which received ‘Below Average’ rainfall including parts of Tasmania, the south east corner of Victoria and New South Wales, a large area in Western Australia and an area in south east Queensland/north east New South Wales (Fig. 1).
Despite some good rain in September, overall rainfall totals across parts of Australia for the last three months remain ‘Below Average’ (Fig. 2). Most notably, large parts of Western Australia, north west Tasmania and across southern South Australia and Victoria. However, some regions particularly in the far south east corner of Victoria, south east New South Wales, parts of central Australia and along the coast in the Northern Territory have had ‘Above Average’ rainfall during July to September (Fig. 2).
The BoM’s ACCESS model predicts that October is likely to deliver ‘Above Average’ rainfall across much of the eastern two thirds of Australia except for parts of Western Australia where there are roughly equal chances of ‘Above’ or ‘Below Average’ rainfall and south west Tasmania where ‘Below Average’ rainfall is likely (Fig. 3).
For the three-month forecast, October to December, rainfall is likely to deliver ‘Above Average’ rainfall for much of mainland Australia and north east Tasmania, however, the north-west of Western Australia has equal chances of ‘Above’ or ‘Below Average’ rainfall and south west Tasmania is likely to be ‘Below Average’ (Fig. 3).
At this time of year accuracy for the three-month forecast is moderate to high across Australia except for an area in Western Australia and parts of the Northern Territory particularly along the borders of South Australia and Queensland where accuracy is low at this time of year (Fig. 3).
Maximum temperatures in September were ‘Above Average’ across much of Australia with some places in Western Australia and the Northern Territory again experiencing ‘Highest on Record’. Mandora in the north west of Western Australia and Victoria River Downs in the Northern Territory recorded 41.8°C and 40.8°C respectively (Fig. 4). Minimum temperatures were also ‘Above Average’ across much Australia, with several areas recording ‘Highest on Record’ (Fig. 5).
The BoM’s ACCESS model forecast suggests that over the next three months maximum temperatures are likely to be ‘Above Average’ across much of northern Australia, the southern regions of Victoria and all of Tasmania (Fig. 6). For all other areas there is an equal chance of maximum temperatures being ‘Above’ or ‘Below Average’ except for the southern coastline of Western Australia where they are likely to be ‘Below Average’ (Fig. 6).
For minimum temperatures, except of a small area in the south west of Western Australia where there are equal chances of ‘Above’ or ‘Below Average’ temperatures the rest of Australia is likely to be ‘Above Average’ (Fig. 7). Note that frosty nights are also still possible particularly in areas like southern Western Australia.
At this time of year accuracy for the three-month maximum temperature forecast is moderate to high for all of Australia except for a small pocket in north east Western Australia (Fig. 6). For minimum temperature over the next three months, accuracy is moderate to high across most of Australia except for most of the Northern Territory and into Western Australia, as well as a small pocket on the Queensland and New South Wales border (Fig. 7).
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