Weekly update - 5 May 2022

For the week ending 4 May 2022, low-pressure troughs in eastern Australia and cold fronts across southern Australia resulted in moderate rainfall. Meanwhile high-pressure systems provided mostly dry conditions for remaining parts of the country.

Rainfall totals of between 10 and 50 millimetres were recorded across north-western to south-eastern New South Wales, much of Victoria, as well as isolated parts of the north of the Northern Territory, Queensland, South Australia and Western Australia. Rainfall totals in excess of 50 millimetres were recorded across much of Tasmania as well as isolated parts of eastern New South Wales, north-eastern Queensland and the north of the Northern Territory. Remaining parts of Australia received little to no rainfall.

In cropping regions, rainfall totals of between 10 and 50 millimetres were recorded across central New South Wales, southern Victoria and isolated parts of eastern Queensland and Western Australia. Rainfall in excess of 50 millimetres was recorded in cropping regions in eastern New South Wales. Little to no rainfall was recorded across cropping regions in remaining parts of New South Wales, Queensland, Victoria, South Australia and Western Australia.

Dry conditions across Queensland and, northern and southern New South Wales likely allowed field access for the harvesting of summer crops, as well as the planting of winter crops. In southern growing regions, planting of winter crops is also well underway. However, rainfall and extremely high upper layer soil moisture levels across parts of New South Wales and Victoria have likely limited field access over the past week. Upper layer soil moisture levels are average to above average across most Australian cropping regions, except for central cropping regions of South Australia which are yet to receive their autumn break to start the winter cropping season.

Rainfall for the week ending 4 May 2022

Rainfall during April 2022 was 27% above average for Australia as a whole. Rainfall was above average to extremely high for most of the eastern half of Australia, the south and west of Western Australia and the north-west of the Northern Territory. However, rainfall was extremely low to below average for south-western Victoria, south-eastern South Australia, a large area of central Australia, as well as western Tasmania.

The main climate influences for April were a La Niña event in the Pacific and a positive South Annular Mode (SAM). A La Niña is associated with above average rainfall for eastern Australia, and a positive SAM typically results in high-pressure systems over the Great Australian Bight, and above average sea surface temperatures to the north-west and south-east of Australia. The combination of high-pressure systems to the south and low-pressure systems off the east coast brought significant falls to parts of central and eastern Australia.

April rainfall was average to above average across cropping regions of New South Wales, northern and south-western Queensland, the west of South Australia, Western Australia and Victoria. Below average falls recorded in cropping regions of south-central Queensland and central South Australia.

Extremely high rainfall across eastern Australia in April followed a wet March and added to already saturate soil profiles, resulting in localised flooding. The wet conditions have delayed maturation and harvesting of long-lived summer crops in parts of New South Wales and Queensland. However, most southern cropping regions have received sufficient rainfall in recent weeks to classify as a consolidated autumn break.

Rainfall percentiles for April 2022

Upper layer soil moisture in April 2022 was extremely low for this time of year across south-western Victoria, south-eastern South Australia, large areas of central Australia, as well as western Tasmania due to below average rainfall in these areas during April. Extremely high upper layer soil moisture was evident across large areas of New South Wales, Queensland, eastern and northern Victoria, the east of South Australia, parts of western and southern Western Australia and northern parts of the Northern Territory reflecting heavy rainfall events in these areas. Modelled upper layer soil moisture was generally average across the remainder of the country.

At this time of year, upper layer soil moisture is important for the germination and establishment of early sown winter crops across Australian cropping regions. It is also important indicator of the ability to access paddocks to undertake harvesting of summer crops in New South Wales and Queensland, as well as planting activities for winter crops.

Upper layer soil moisture was average to above average for this time of year across cropping regions in New South Wales, Victoria and Western Australia, much of Queensland and western South Australia. Upper layer soil moisture was below average for isolated parts of the southern Queensland and central South Australia growing regions. Extremely high to above average upper layer soil moisture was evident across much of central New South Wales, western Queensland and the east of Western Australia cropping regions. Extremely high upper layer soil moisture would have prevented field access for growers across parts of New South Wales. However, the above average upper layer soil moisture levels across most cropping regions will support winter crops through germination and establishment.

Modelled upper layer soil moisture for April 2022

Lower layer soil moisture for April 2022 was well above average to extremely high for this time of year across eastern New South Wales, parts of south-eastern, central and northern Queensland, eastern and north-western Victoria, as well as isolated parts of South Australia and large areas in central and the west of Western Australia. Lower layer soil moisture was well below average to below average across large parts of northern Queensland, southern Victoria, the south-east of South Australia, isolated parts of Western Australia, the north of the Northern Territory and much of Tasmania.

In cropping regions, lower layer soil moisture was well above average to extremely high for parts of New South Wales, southern Queensland, western Victoria, as well as much of Western Australia. Lower layer soil moisture was extremely low to below average for parts of Central Queensland and central South Australian cropping regions. The below average lower layer soil moisture may reduce yield potentials for late sown summer crops in Central Queensland as their root systems extend into lower soil layers. Similarly, pasture growth in northern parts of Queensland and the Northern Territory has likely struggled due to the lack of lower layer moisture.

Modelled lower layer soil moisture for April 2022

February to April forms the final 3-months of the pasture growing season across much of northern Australia, providing a late season boost in growth and the bulk of feed to maintain production through the low pasture growth months of the northern dry season. Across south-eastern Australia, February to April pasture growth is typically increasing reflecting higher rainfall totals, and reduced temperatures and evapotranspiration rates at this time of year. Pasture availability during this period influences the growth and branding and marking rates of lambs and calves, livestock turnoff and the production of meat, milk, and wool.

For the 3 months to April 2022, above average rainfall totals and mild temperatures resulted in average to well above average pasture production for this time of year across most grazing regions in central and western New South Wales, southern Queensland, western and northern Victoria, northern South Australia, northern Western Australia, and the south of the Northern Territory. Extremely low to below average pasture growth rates were recorded across central Western Australia, south-eastern Victoria, parts of central and northern Queensland and the north of the Northern Territory consistent with above average temperatures and/or below average rainfall. In contrast, below average pasture growth rates across parts of eastern New South Wales and south-eastern Queensland are likely the result of below average temperatures and waterlogged soils.

Average to extremely high pasture production across much of New South Wales, Victoria, southern Queensland, South Australia, northern Western Australia and the south of the Northern Territory will likely enable farmers to continue to rebuild stock numbers and provide opportunities to build standing dry matter availability. Below average temperatures and waterlogged soils across eastern New South Wales and south-eastern Queensland may have restricted summer pasture growth. However, it comes after extremely high pasture growth during winter and spring that supplied average to above average pasture availability and ample opportunities to conserve excess fodder. 

Relative pasture growth for 3-months ending April 2022 (1 February to 30 April 2022)

Over the 8-days to 12 May 2022, low-pressure systems, fronts and troughs, coupled with onshore winds are expected to bring showers and storms to eastern Australia. In remaining parts of the country, high-pressure systems will bring mostly dry conditions.

Rainfall totals of between 10 and 50 millimetres are forecast for much of northern and eastern New South Wales, much of Queensland, Tasmania, the far south-west of Western Australia and scattered areas of Victoria. Rainfall in excess of 50 millimetres is expected for the far north-east of New South Wales, much of the eastern half of Queensland, as well as parts of western and southern Tasmania.

In Australian cropping regions, rainfall totals of between 10 and 50 millimetres are expected across central and northern New South Wales and isolated areas of southern Queensland. Rainfall in excess of 50 millimetres is expected across most cropping regions in Queensland. Little to no rainfall is forecast for all remaining cropping regions during the next 8-days.

The wet conditions expected across Queensland and northern New South Wales cropping regions is likely to restrict field access, delaying the harvesting of cotton and sorghum, as well as the planting of winter crops. The dry conditions expected across southern New South Wales cropping regions will allow the harvesting of cotton and rice to continue, as well as the planting of winter crops. In Victoria, South Australia and Western Australia, planting activity is expected to increase over the coming week, with relatively dry conditions. Many growers will be eager to complete planting programs as soon as possible given the expectation for a wetter than average winter. The east of South Australia is still yet to receive an autumn break, but growers are likely to dry-sow winter crops given the favourable 3-month rainfall outlook.

Total forecast rainfall (mm) for the period 5 May to 12 May 2022