Weekly update - 4 February 2021

During the 7 days to 3  February 2021, troughs, low-pressure systems and weak cold fronts generated showers and thunderstorm activity across parts of northern, western and south-eastern Australia.

Rainfall totals of between 15 and 100 millimetres were recorded across much of New South Wales, Victoria and the northern half of Western Australia, and parts of northern Queensland, southern Western Australia and the centre and north of the Northern Territory. Similar rainfall totals were recorded across scattered parts of the remainder of Queensland and South Australia. Rainfall totals in excess of 100 millimetres were recorded across parts of northern Western Australia and isolated parts of the northern Queensland and the north of the Northern Territory.

In Australia’s summer cropping regions, rainfall totals of between 10 and 50 millimetres were generally restricted to northern New South Wales and isolated parts of northern Queensland during the 7 days to 3  February 2021.

In those summer cropping regions that recorded rainfall during the 7 days to 3  February 2021, these falls are likely to benefit the production prospects and yield potential of dryland crops.

Rainfall for the week ending 3 February 2021

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

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/

January 2021 was warmer than average nationally with a national mean temperature of 0.26°C above average and a mean minimum temperature of 0.46°C above average.

Maximum temperatures for January were very much below average to below average across large parts of central-western and eastern Australia. Similarly, minimum temperatures were below average across parts of central-western Australia. Minimum temperatures were very much above average to above average across large parts of the western coastline, northern Australia and western Queensland. Maximum temperatures were very much above average to above average across the western coastline. Across eastern Australia, average minimum temperatures coupled with substantial rainfall are likely to have benefitted production prospects of dryland summer crops.

Maximum temperature deciles for January 2021

©Commonwealth of Australia 2021, Australian Bureau of Meteorology - Issued: 01/02/2021

Minimum temperature deciles for January 2021

©Commonwealth of Australia 2021, Australian Bureau of Meteorology - Issued: 01/02/2021

Note: Maximum and minimum temperatures for January 2021 compared with temperature recorded for that period during the historical record (1900 to present). For further information go to: http://www.bom.gov.au/water.

Rainfall during January  2021 was below average nationally. Rainfall was severely deficient to below average across parts of eastern and north-western Queensland, Western Australia and the centre of the Northern Territory. Rainfall was above average to extremely high across much of Victoria and parts of western New South Wales, northern Queensland, southern South Australia, northern and eastern Western Australia and the far north of the Northern Territory.

La Niña remained at moderate levels in January. The Southern Annular Mode (SAM) was positive at the start of the month and generally neutral for the remainder of January. During summer, La Niña and a positive SAM typically increase the chance of rainfall in northern and eastern Australia. When SAM is neutral it has low influence on rainfall. Active monsoon conditions and an active Madden–Julian Oscillation (MJO) during January were influencing the development of tropical lows, cyclones and above average rainfall across parts of northern Australia.

In summer cropping regions, January rainfall was generally average across New South Wales and Queensland. Rainfall was above average to extremely high across isolated parts of northern and western New South Wales, and central and southern Queensland. It was below average across isolated parts of northern and eastern Queensland. The substantial rainfall likely benefitted the production prospects and yield potential of dryland crops in eastern Australia. Despite below average January rainfall across parts of northern Australia, rainfall totals and stored soil moisture have been sufficient to maintain average to above average pasture production and support livestock restocking confidence.

Rainfall percentiles for January 2021

Source: Bureau of Meteorology
Note: Rainfall for January  2021 is compared with rainfall recorded for that period during the historical record (1900 to present). For further information, go to http://www.bom.gov.au/water/

Upper layer soil moisture in January  2021 was above average to extremely high for this time of year across much of south-eastern Australia and parts of central and northern Australia, largely reflecting rainfall patterns during the month. Modelled soil moisture was extremely low to below average across isolated parts of northern and western Australia. Upper layer soil moisture is less important after plant germination and establishment has occurred because plants can access lower soil moisture.

Relative upper layer soil moisture was above average to extremely high for this time of year across cropping regions in northern and western New South Wales and southern Queensland. Soil moisture was generally average across remaining cropping regions in Queensland and New South Wales.

Modelled upper layer soil moisture for January 2021

Source: Bureau of Meteorology (Australian Water Resources Assessment Landscape model)
Note: This map shows the levels of modelled upper layer soil moisture (0 to 10 centimetres) during January 2021. This map shows how modelled soil conditions during January 2021 compare with January conditions modelled over the reference period (1911 to 2016). Dark blue areas on the maps were much wetter in January 2021 than during the reference period. The dark red areas were much drier than during the reference period. The bulk of plant roots occur in the top 20 centimetres of the soil profile. Soil moisture in the upper layer of the soil profile is therefore useful indicator of the availability of water, particularly for germinating seed.

Lower layer soil moisture for January  2021 was above average to extremely high for this time of year across large parts of northern, central and eastern Australia. Lower layer soil moisture was extremely low to below average across parts of Western Australia and South Australia.

In summer cropping regions, lower layer soil moisture was average to extremely high for much of northern New South Wales and parts of southern and northern Queensland. Soil moisture is average across remaining summer cropping regions.

Modelled lower layer soil moisture for January 2021

Source: Bureau of Meteorology (Australian Water Resources Assessment Landscape model)

Note: This map shows the levels of modelled lower layer soil moisture (10 to 100 centimetres) during January  2021. This map shows how modelled soil conditions during January  2021 compare with January conditions modelled over the reference period (1911 to 2016). Dark blue areas on the maps were much wetter in January  2021 than during the reference period. The dark red areas were much drier than during the reference period. The bulk of plant roots occur in the top 20 centimetres of the soil profile. The lower layer soil moisture is a larger, deeper store that is slower to respond to rainfall and tends to reflect accumulated rainfall events over longer time periods.

Troughs, low-pressure systems, onshore flow and a strong cold front are expected to generate showers and storms over parts of northern, western and eastern Australia during the next 8 days.

Rainfall totals of between 10 and 50 millimetres are forecast for much of New South Wales, central and eastern Victoria, central and south-western Queensland, western and northern Western Australia, the south of the Northern Territory and Tasmania. Rainfall totals in excess of 50 millimetres are expected across parts of northern Queensland, western and northern Western Australia and the northern half of the Northern Territory, as well as isolated parts of eastern Victoria and northern Tasmania.

In Australia’s summer cropping regions, rainfall of between 10 and 50 millimetres is expected across western and central New South Wales and western and northern Queensland. Rainfall of between 5 and 10 millimetres is expected across most summer cropping regions in north-eastern New South Wales and south-eastern Queensland. Little to no rainfall is expected across the remaining parts of south-eastern Queensland summer cropping regions.

Total forecast rainfall (mm) for the period 4 February to 11 February 2021

©Commonwealth of Australia 2021, Australian Bureau of Meteorology - Issued: 04/02/2021

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.