THE CLIMATE KELPIE BLOG: What’s predicted in November?

Posted by BCG on 12th November 2021

The negative Indian Ocean Dipole (-IOD) continues to weaken and is expected to return to neutral in November. This is typical of the IOD event lifecycle as we have now entered the monsoon season. As the monsoon trough shifts south over the tropical Indian Ocean it changes the wind patterns and prevents an IOD event from forming between December and April. Whilst the -IOD event continues to breakdown the waters to the north of Australia are still warmer than normal which is helping to generate moisture in the region and contributing towards ‘Above Average’ rainfall for eastern and southern parts of Australia.

In terms of the El Niño-Southern Oscillation (ENSO), this climate driver remains neutral, however further cooling in the tropical Pacific Ocean has resulted in the BoM moving its ENSO Outlook Status to La Niña ALERT. Most models are now indicating that the La Niña threshold will be met during November and maintained until at least January 2022. Regardless of a La Nina forming or not this activity in the Pacific Ocean is also contributing to the increased chances of ‘Above Average’ rainfall for much of eastern and northern Australia.

Our shorter-term climate driver, the Southern Annular Mode (SAM) is currently positive and is forecast to be positive for much of November and December. A positive SAM during summer typically brings ‘Above Average’ rainfall to eastern parts of Australia, except western Tasmania. 

The Madden-Julian Oscillation (MJO) is currently over Papa New Guinea and is moderate. A minority of models are however forecasting it to strengthen and move eastwards to the western Pacific. If the MJO strengthens it would increase the chances of ‘Above Average’ rainfall across north-east Australia. The overall outlook for November to January is therefore for likely rainfall to be ‘Above Average’ for much of the eastern two-thirds of Australia and extending into eastern parts of Western Australia. In terms of temperatures, maximums are likely to be ‘Above Average’ for much of western Western Australia, parts of the north-east coastline, and the far south-east of Australia. Central Australia, extending into the north-west and south-west parts of Australia, as well as eastern NSW extending into southern Queensland are however likely to experience ‘Below Average’ maximum temperatures. Minimum temperatures are forecast to be ‘Above Average’ for most parts of the country except for southern parts of Western Australia where the chances are equal for ‘Above’ or ‘Below Average’.

Rainfall Roundup

In October, rainfall was ‘Above Average’ for much of coastal Queensland extending down into Victoria, northern and eastern Tasmania, western Western Australia as well as large parts of the Northern Territory and Queensland (Fig 1). The rest of Australia was ‘Average’ except for the northern tip of Western Australia, central New South Wales, small pockets in Queensland and an area centred around the junction of the South Australia, Northern Territory and Western Australia borders where rainfall was ‘Below Average’ (Fig. 1).

Over the last three months, much of southern and central Western Australia as well as most of South Australia has received ‘Below Average’ rainfall (Fig. 2). Rainfall deficiencies are also starting to show up in south-east Queensland as well as parts of northern and western Victoria (Fig. 2). In contrast much of Tasmania as well as northern Australia and south-east Victoria have received ‘Above Average’ rainfall (Fig. 2).

Figure 1. Rainfall deciles for October 2021.
Figure 2. Rainfall deciles for August 2021 to October 2021.

Rainfall Forecast

The BoM’s ACCESS model predicts that rainfall in November is likely to be ‘Above Average’ for much of Australia excluding south east Queensland, south-west Tasmania and western parts of Western Australia where equal chances of rainfall being ‘Above’ or ‘Below Average’ are likely (Fig. 3). For the three-month forecast, November to January, rainfall is likely to be ‘Above Average’ for the eastern two thirds of the country (Fig. 3). A small area of western Tasmania is however likely to be ‘Below Average’ as well as parts of the Pilbara region in Western Australia. For the remainder of Western Australia there are equal chances of ‘Above’ or ‘Below Average’ rainfall (Fig. 3).

At this time of year accuracy for the three-month forecast is moderate to high for most of Australia except for southern and western South Australia, eastern parts of Western Australia as well as pockets of the Northern Territory where accuracy is low (Fig. 3). 

Figure 3. Australian rainfall outlook for November 2021 to January 2022.

Temperature Roundup

Maximum temperatures in October were ‘Very Much Above Average’ to ‘Highest on Record’ across northern Australia with records tumbling. Tennant Creek recorded it’s warmest October day on record with 43°C on 21st October. Maximum temperatures were ‘Below Average’ in central New South Wales, south-east and south-west Victoria, eastern Tasmania, south-east South Australia as well as a large part of south-west Western Australia (Fig. 6).

Minimum temperatures were also ‘Above Average’ across much of northern Australia as well as Tasmania, the coastline of Victoria and south east Western Australia (Fig. 5). In contrast, large parts of south east mainland Australia as well as north-central and south-western Western Australia were ‘Below Average’ (Fig. 5).

Figure 4. Maximum temperature deciles for October 2021.
Figure 5. Minimum temperature deciles for October 2021.

Temperature Forecast

The BoM’s ACCESS model predicts that over the next three months maximum temperatures are likely to be ‘Above Average’ for coastal parts of northern Australia as well as all of Tasmania, north-east and western regions of Victoria stretching into south-east South Australia and the central-west of Western Australia (Fig. 6). For coastal New South Wales, central Australia and southern parts of Western Australia there is an increased chance of ‘Below Average’ maximum temperatures (Fig. 6).

For minimum temperatures, much of Australia is likely to be ‘Above Average’ for the next three months, except for southern parts of Western Australia where they have an equal chance of being ‘Above’ or ‘Below Average’ (Fig. 7).

At this time of year accuracy for the three-month maximum temperature forecast is moderate to high for all of Australia (Fig. 6). For minimum temperatures, accuracy is moderate to high for much of Australia excluding a small pocket in Western Australia near the Northern Territory border where accuracy is low (Fig. 7). 

Figure 6. November 2021 to January 2022 maximum temperature outlook.
Figure 7. November 2021 to January 2022 minimum temperature outlook.

Climate and Water Outlook Videos

The Bureau of Meteorology releases regular outlook videos, covering all this information. Watch the most recent video below.

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