Weekly update - 11 March 2021

During the week ending 10 March 2021, troughs, low-pressure systems and cold fronts generated thunderstorms and showers across parts of eastern, western and northern Australia.

Rainfall totals of between 15 and 50 millimetres were recorded across parts of north-eastern New South Wales, Queensland, Western Australia, the north of the Northern Territory and western Tasmania. Rainfall in excess of 50 millimetres was recorded across parts of northern Australia and isolated parts of north-eastern New South Wales and southern Western Australia.

In Australia’s cropping regions, rainfall totals of between 15 and 50 millimetres were recorded across much of Western Australia and parts of north-eastern New South Wales and south-eastern and northern Queensland. Little to no rainfall was recorded across remaining cropping regions.

The recent rainfall in western cropping regions is likely to provide an early boost to soil moisture ahead of the sowing of winter crops during autumn and early winter. Little to no rainfall across most of the Queensland cropping regions would have allowed summer crop harvest activities to proceed without delay.

Rainfall for the week ending 10 March 2021

©Commonwealth of Australia 2021, Australian Bureau of Meteorology - Issued: 10/03/2021
Note: The rainfall analyses and associated maps utilise data contained in the Bureau of Meteorology climate database, the Australian Data Archive for Meteorology (ADAM). The analyses are initially produced automatically from real-time data with limited quality control. They are intended to provide a general overview of rainfall across Australia as quickly as possible after the observations are received. For further information go to http://www.bom.gov.au/climate/rainfall/

As the generally favourable summer cropping and northern pasture production season wraps up, interest moves to the prospects for autumn and the start of the winter cropping season. To gain some insight, it is important to look at the climate drivers—the El Niño–Southern Oscillation (ENSO) and the Madden–Julian Oscillation (MJO)—that can influence autumn rainfall across Australia.

Oceanic indicators continue to suggest the La Niña event in the tropical Pacific has likely passed its peak. La Niña events typically generate favourable growing conditions for summer crop and pasture production. This has been evident across most of northern and eastern Australia during summer. These favourable growing conditions were central in developing ABARES summer crop and livestock production forecasts embodied in the ABARES March 2021 edition of the Agricultural commodities and February 2021 edition of the Australian crop report. These favourable agricultural production conditions are likely to continue though the autumn period as enhanced rainfall associated with La Niña typically continues while the event weakens.

In the past fortnight, sea surface temperature anomalies in the tropical Pacific Ocean have generally remained steady. Cool sea surface temperature anomalies persist across the equatorial Pacific and parts of the eastern Pacific. Warm sea surface temperature anomalies in the waters near north-eastern, western and south-eastern Australia have strengthened slightly. Warm anomalies in the waters near Indonesia and the Philippines have weakened slightly. As at 2 March 2021 almost all of the international climate models surveyed are expecting sea surface temperature across the equatorial Pacific to remain at neutral or close to neutral ENSO values until at least July.

Difference from average sea surface temperature observations 22 February to 28 February 2021

International climate model outlooks for the NINO 3.4 region in July 2021

©Commonwealth of Australia 2021, Australian Bureau of Meteorology - Issued: 02/03/2021

Atmospheric indicators continue to be generally consistent with the current La Niña event, with stronger than average to near average trade winds and decreased cloudiness near the Date Line. For the period ending 7 March the 30‑day Southern Oscillation Index (SOI) value was 8.1 and for the period ending 28 February the 90‑day value was 15.3. The SOI values have been declining since January. The SOI remains within La Niña thresholds, with sustained values above +7.

30-day Southern Oscillation Index (SOI) values ending 7 March 2021

As at 9 March 2021 the Madden–Julian Oscillation (MJO) was weak in strength and its location was indiscernible. The MJO is a pulse of cloud and rainfall that moves eastward along the equator. Most models suggest the MJO could strengthen and move over the Americas and Africa before weakening over the western Indian Ocean during the next fortnight. An MJO pulse over the Americas and Africa would likely influence below average rainfall across northern Australia.

Madden–Julian Oscillation (MJO) daily index

Note: This map displays the forecast outgoing longwave radiation (OLR) difference from expected cloudiness to identify convective rain clouds and the position of the Madden–Julian Oscillation (MJO). The blue shading indicates higher than normal, active or enhanced tropical weather and the brown shading indicates lower than normal clouds or suppressed conditions.

These climate outlooks are generated by ACCESS–S (Australian Community Climate Earth-System Simulator–Seasonal). ACCESS–S is the Bureau of Meteorology's dynamical (physics-based) weather and climate model used for monthly, seasonal and longer-lead climate outlooks.

For further information, go to http://www.bom.gov.au/climate/ahead/about/

The latest rainfall outlook released by the Bureau of Meteorology suggests that wetter than average conditions are more likely for parts of northern Australia during April 2021, consistent with a weakening La Niña event.

The outlook for April 2021 indicates that there is a 75% chance of rainfall totals between 10 and 100 millimetres across parts of the eastern coast of Australia, southern Victoria, eastern Tasmania and scattered parts of Western Australia. Rainfall totals in excess of 100 millimetres are expected across isolated parts of north-eastern Queensland, the far north of the Northern Territory and western Tasmania.

Across most cropping regions there is a 75% chance of rainfall totals between 1 and 10 millimetres. There is a 75% chance of rainfall totals of up to 25 millimetres across cropping regions in parts of eastern New South Wales, central Queensland, southern Victoria and eastern Western Australia.

The ACCESS-S climate model suggests there is a 50% chance of recording close to average April rainfall totals across much of Australia, including the major cropping regions. This would suggest that it is less likely that most cropping regions across eastern Australia would experience a repeat of last season’s early autumn break which facilitated widespread planting of winter crop under ideal sowing conditions. 

Rainfall totals that have a 75% chance of occurring April 2021

©Commonwealth of Australia 2021, Australian Bureau of Meteorology - Issued: 04/03/2021

The rainfall outlook for April to June 2021 suggests there is a greater than 60% chance of above average rainfall across much of northern Australia and parts of New South Wales There is less than a 40% chance of exceeding median rainfall in isolated parts of Western Australia (Bureau of Meteorology ‘National Climate Outlook’, 4 March 2021). Bureau of Meteorology rainfall outlooks for April to June have greater than 55% past accuracy across much of Queensland, Victoria, Western Australia and the Northern Territory. The outlooks have greater than 65% past accuracy for parts of northern Australia, western Victoria and south-eastern South Australia.

Chance of exceeding the median rainfall April to June 2021

©Commonwealth of Australia 2021, Australian Bureau of Meteorology - Issued: 04/03/2021

The outlook for April to June 2021 suggests there is a 75% chance of rainfall totals between 25 and 100 millimetres across much of eastern, south-western and far northern Australia. Rainfall totals in excess of 100 millimetres are likely across parts of eastern New South Wales, eastern Queensland, southern Victoria, south-eastern South Australia, south-western Western Australia, the north of the Northern Territory and Tasmania.

Across cropping regions, there is a 75% chance of receiving between 50 and 100 millimetres across much of New South Wales, Victoria, South Australia, Western Australia and parts of south-eastern Queensland. Lower totals of between 25 and 50 millimetres are expected across remaining cropping regions between April and June 2021.

There is a 50% chance of recording close to average April to June rainfall across most winter cropping regions. Given the average or better soil moisture levels across cropping regions in much of New South Wales, South Australia and Western Australia, these falls will likely support average or better pasture growth, as well as the planting of winter crops.

Rainfall totals that have a 75% chance of occurring April to June 2021

©Commonwealth of Australia 2021, Australian Bureau of Meteorology - Issued: 04/03/2021

The temperature outlook for April to June 2021 indicates that day-time and night-time temperatures across most of Australia are likely to be close to the 1990-2012 average (- 1°C to 1°C) (Bureau of Meteorology ‘National Climate Outlook’, 4 March 2021).

Predicted maximum temperature anomaly for April to June 2021

Predicted minimum temperature anomaly for April to June 2021

Troughs, onshore flow and cold fronts are expected to generate showers and storms over parts of northern and eastern Australia during the next 8 days.

Rainfall totals of between 10 and 50 millimetres are forecast for much of eastern New South Wales, eastern and northern Queensland, eastern Victoria, northern Western Australia, the north and west of the Northern Territory and western Tasmania. Rainfall totals in excess of 50 millimetres are forecast for parts of north-eastern New South Wales, northern Western Australia and the north of the Northern Territory.

In Australia’s cropping regions, rainfall of between 15 and 50 millimetres is expected for much of Queensland and parts of western and central New South Wales. Rainfall up to 100 millimetres is expected in cropping regions across north-eastern New South Wales.

Total forecast rainfall (mm) for the period 11 March to 18 March 2021

©Commonwealth of Australia 2021, Australian Bureau of Meteorology - Issued: 11/03/2021

Note: This rainfall forecast is produced from computer models. As the model outputs are not altered by weather forecasters, it is important to check local forecasts and warnings issued by the Bureau of Meteorology.