Weekly Rainfall Update

For the week to 16 January 2018, rainfall was recorded in most of Western Australia, the Northern Territory, northern and northwestern Queensland, the eastern half of New South Wales, Victoria and Tasmania.

At the start of the week, the monsoon trough over the Australian northwest coast and a developing tropical low near the west Kimberley in Western Australia  produced extensive thunderstorms in the Top End of the Northern Territory and the Kimberley coast, with tropical moisture streaming southeast into South Australia. A surface trough and upper level disturbance in southwest Western Australia produced an active cloudband with isolated, embedded showers and thunderstorms. Moderate rainfall totals were recorded over southern Western Australia and western parts of South Australia. In the east, a surface trough moving across southeastern Australia produced thunderstorms with light to moderate fall in eastern New South Wales and Tasmania.

The tropical low developed into a tropical cyclone on 11 January, named tropical cyclone Joyce. The system tracked southwards and made landfall in the far west Kimberley coast near Wallal the next day. Tropical cyclone Joyce soon weakened to a tropical low and moved southwest through the Pilbara and northern Gascoyne.  Heavy rainfall with localised very heavy falls was recorded along the system's passage about the western Kimberley, Pilbara and Gascoyne, with moderate falls recorded across much of northern Australia and central Australia, while a series of surface troughs delivered moderate falls across southern Western Australia and South Australia, also. Widespread light to moderate falls were also recorded in southeastern Australia, including Tasmania during the middle of the week.

From the latter part of the week, ex-tropical cyclone Joyce tracked south parallel to the west coast of Western Australia. The system brought widespread moderate to heavy falls from the northwest to the southwest of Western Australia Heavy rainfall with daily totals in excess of 100 mm around the Perth area saw some January daily rainfall records at the end of the week. An extensive surface trough across the tropical north also produced thunderstorms with moderate rainfall to the northern and central Western Australia, the western Top End in Northern Territory, and the Cape York and tropical north coast of Queensland.

Rainfall totals exceeding 100 mm were recorded in parts of the northwestern Top End in the Northern Territory, and along the Kimberley and Gascoyne coasts and adjacent inland districts; also in areas of the southwest coast of Western Australia. The highest weekly total was 310 mm at Wallal Downs in Western Australia.

Rainfall totals between 50 mm and 100 mm were recorded in areas of northern and eastern Queensland, in areas of eastern New South Wales, far eastern Victoria, and in the southwest and northwest of the Northern Territory. Similar totals were recorded in the Kimberley, Pilbara, parts of the Gascoyne, central interior, and along the southwest coast of Western Australia surrounding heavier falls.

Rainfall totals between 10 mm and 50 mm were recorded in northern, western and southwestern parts of Western Australia, southwest and northwest South Australia, central and eastern Victoria, much of the eastern half of New South Wales. Similar totals were recorded in southern, western and northwestern parts of the Northern Territory, and northwestern and northern Queensland.

Little or no rainfall was recorded in eastern inland parts of Western Australia, northeastern South Australia, northwestern Victoria, western New South Wales, southern Queensland and some eastern parts of the Northern Territory.

Impact of recent rainfall on deficits

The Drought Statement, issued on 9 January 2018, discusses rainfall deficits over Australia for the 7-month (June 2017–December 2017) and 10-month (March 2017–December 2017) periods. The rainfall deficit map is available for this period as well as for standard periods.

The maps below show the percentage of mean rainfall that has been received for the rainfall deficit period for the 7- and 10-month periods ending 16 January 2018.

Rainfall for the period 1 June 2017 to 16 January 2018

Serious to severe deficiencies persist at the 7-month period in areas of the western to central Pilbara in Western Australia. Deficiencies are also evident in central eastern New South Wales and along the east coast of Tasmania; and in scattered locations across the south of Western Australia and near Port Augusta in South Australia, far eastern Victoria, and central to western Queensland.

Rainfall in the last week has slightly eased deficiencies in the Pilbara, as affected areas have received less than 40% to 50% of the average for the period. Remaining affected areas have generally received between 40% and 60% of average.

Rainfall for the period 1 March to 16 January 2018

Serious to severe rainfall deficiencies persist at the 10-month period persist along the west coast of Western Australia between about Exmouth and north of Perth, extending inland east to parts of the South West Land Division and southwest of the Goldfields District. Deficiencies are also present in scattered parts of western and central Queensland, and near Ceduna in South Australia.

Rainfall in the last week has eased deficiencies in the Pilbara and areas along the west coast, south of the Gascoyne. Affected areas have received less than 50% to 70% of the average for the period.

Affected areas in far western Queensland received less than 30% of the average, while areas in central Queensland have received between 30% and 50% of the average for the period.  Affected areas in South Australia, eastern Victoria and Tasmania received less than 70% to 80% of the average for the period.

Map of rainfall totals for this week

Product code: IDCKGRWAR0