November rainfall eases deficiencies in South Australia and New South Wales
Rainfall for November was above to very much above average for nearly all of the Northern Territory and South Australia, parts of Western Australia in the Kimberley, the southeast, and in parts of the Pilbara and Gascoyne and western interior, parts of the Gulf Country and northwestern Queensland, western Victoria and parts of southwestern and southeastern New South Wales. Monthly totals were in the highest 10% of historical observations (decile 1) for November in large parts of South Australia and the Northern Territory.
Monthly rainfall totals were below average for the eastern half of southern Victoria, from Melbourne to Cann River in Gippsland, nearly all of Tasmania, the southwest of Western Australia and part of the Gascoyne, and scattered pockets of eastern Australia, mostly close to the coast.
A long-lived blocking high over the Tasman Sea during much of November brought persistently northerly airflow across most of Victoria and Tasmania, with associated warm temperatures and low rainfall, continuing rainfall deficiencies in both States. A Special Climate Statement was issued discussing the record-breaking warmth. Following this warm spell, a heavy rainfall event across the southeast saw large areas of northern Victoria and southern New South Wales received two to three times the average December rainfall total during the first four days of the month. See also comparison of percentage of mean rainfall over southeastern Australia for the 6-month period ending November 2017, before and after early December rainfall.
November rainfall has eased deficiencies across parts of the coastline at the top of the Great Australian Bight, across the top of the Eyre Peninsula in South Australia, and parts of southern New South Wales at both the 6- and 9-month timescales. Rainfall during the first days of December has further alleviated deficiencies in these areas, while serious to severe deficiencies remain little changed in eastern Victoria, eastern Tasmania, and on the western to northwestern coast of Western Australia.
6-month rainfall deficiencies
Serious to severe rainfall deficiencies are present in areas along the coast of Western Australia in the Gascoyne and Pilbara, in areas of coastal South Australia around Ceduna and Port Augusta, across areas between western New South Wales and the Central Tablelands and western slopes of the Great Dividing Range, in much of eastern Victoria, and along the east coast of Tasmania.
Deficiencies have been cleared from areas of the southern coast between the Eucla in Western Australia and Ceduna in South Australia, across parts of South Australia's northern agricultural districts, and across parts of southern New South Wales.
9-month rainfall deficiencies
Rainfall deficiencies persist along the west coast of Western Australia between about Exmouth and Perth, with areas of deficiencies having emerged in the southwest compared to the previous 8-month period. Deficiencies are also in place in an area around Ceduna in coastal South Australia, across most of Gippsland in Victoria, and across the east coast of Tasmania. Scattered small pockets of western New South Wales and western to central Queensland have also observed serious rainfall deficiencies at the 9-month timescale.
Rainfall during the past month cleared deficiencies in areas of coastal South Australia west of Ceduna. Conversely, deficiencies have increased in severity in East Gippsland and tight along the east coast of Tasmania.
Soil moisture in the lower layer (from 10 cm to 100 cm deep) for November increased across parts of southeastern Australia, and across much of the central and northern Northern Territory, compared to values for October.
Soil moisture was above average for Central Australia, much of Queensland, the Northern Territory, and much of Western Australia between the interior and the Kimberley.
Lower-layer soil moisture was below average for the western Pilbara in Western Australia, large areas along the southern coast of Western Australia and South Australia, the eastern half of Victoria, extending across most of eastern New South Wales, and across nearly all of Tasmania.
- November rainfall above to very much above average across the Northern Territory, South Australia, western Victoria, parts of Western Australia, particularly in the Kimberley, Gascoyne and adjacent inland, and parts of northwestern Queensland
- Rainfall during November below average for nearly all of Tasmania and eastern Victoria
- Serious to severe rainfall deficiencies remain at the 6-month timescale in the Gascoyne and Pilbara in Western Australia, parts of South Australia's northern agricultural districts, areas of New South Wales between the west and eastern tablelands, in eastern Victoria, and east coast Tasmania
- Serious to severe rainfall deficiencies are evident at the 9-month timescale near the west coast of Western Australia, near Ceduna on the South Australian coast, in east coast Tasmania, eastern Victoria, and small areas in central to western Queensland and western New South Wales
- Lower-layer soil moisture was below average for November in the Pilbara in Western Australia and across large areas of southern Australia, particularly for eastern Victoria and all of Tasmania
Product code: IDCKGD0AR0
Soil moisture details are reported when there are periods of significant rainfall deficits.
Soil moisture data is from the Bureau's Australian Water Resources Assessment Landscape (AWRA-L) model, developed through the Water Information Research and Development Alliance between the Bureau and CSIRO.
See: Australian Landscape Water Balance.
What is drought?
Drought is a prolonged, abnormally dry period when the amount of available water is insufficient to meet our normal use. Drought is not simply low rainfall; if it was, much of inland Australia would be in almost perpetual drought. Because people use water in so many different ways, there is no universal definition of drought. Meteorologists monitor the extent and severity of drought in terms of rainfall deficiencies. Agriculturalists rate the impact on primary industries, hydrologists compare ground water levels, and sociologists define it by social expectations and perceptions.
It is generally difficult to compare one drought to another, since each drought differs in the seasonality, location, spatial extent and duration of the associated rainfall deficiencies. Additionally, each drought is accompanied by varying temperatures and soil moisture deficits.
Rainfall averages, variability and trends
- Average rainfall: How much rain do you expect?
- Rainfall variability: How consistent is rainfall in your area?
- Rainfall history: Check tables, graphs and data from your local weather station.
- Rainfall trends: Has your rainfall changed?
Lowest on record - lowest since at least 1900 when the data analysed begin.
Severe deficiency - rainfalls in the lowest 5% of historical totals.
Serious deficiency - rainfalls in the lowest 10% of historical totals, but not in the lowest 5%.
Very much below average - rainfalls in the lowest 10% of historical totals.
Below average - rainfalls in the lowest 30% of historical totals, but not in the lowest 10%.
Average - rainfalls in the middle 40% of historical totals.
Above average - rainfalls in the highest 30% of historical totals, but not in the highest 10%.
Very much above average - rainfalls in the highest 10% of historical totals.
For the week to 5 December 2017, rainfall was recorded in all States and Territories, although it was dry for most of inland Western Australia.
At the beginning of the week, a broad surface low and associated upper level trough near the Western Australia–South Australia border produced an active line of thunderstorms, with moderate falls recorded over southeast Western Australia, South Australia and the Northern Territory. A surface trough over inland Queensland and northern New South Wales combined with an upper level disturbance, and produced extensive showers and thunderstorms over central and southern Queensland, and northern New South Wales.
In eastern Queensland, a moist onshore flow produced moderate falls along the east coast of Queensland from early in the week.
During the middle of the week, the combination of a broad area of low pressure and an upper level trough generated a cloudband with widespread thunderstorms extending from northwestern Australia through to central Australia, New South Wales, Victoria and Tasmania. Embedded thunderstorms extended across southeastern Australia, driven by tropical moisture combining with an upper level trough and an associated cut-off low over southern New South Wales. Moderate to heavy rainfall totals were recorded across the eastern half of Victoria, western and southern New South Wales, with moderate falls also over much of Tasmania.
Thunderstorms also developed through central Queensland, the northern half of the Northern Territory and northern Western Australia while rain continued along the ranges in eastern Australia and in Tasmania. A band of cloud with embedded thunderstorms extended along a surface trough from the Top End over the east coast of Queensland and into the Tasman Sea, wrapping around a low pressure system to the east of Tasmania.
At the end of the week, the low pressure centre intensified while located to the southeast of Tasmania, producing further rainfall over Tasmania. A surface trough was responsible for embedded thunderstorms and moderate rainfall totals over southeast Queensland and northeast New South Wales, with onshore flow bringing rain to southeastern New South Wales, and moderate to locally heavy falls from showers over the Kimberley.
Rainfall totals in excess of 200 mm were recorded in areas of northeastern Victoria, southeastern New South Wales, and southeastern Queensland. The highest weekly total was 210 mm at Stump Hill (Barjar) in northeastern Victoria.
Rainfall totals exceeding 100 mm were recorded in areas of the Kimberley, Top End, and Cape York Peninsula; in parts of Queensland’s east coast; southeastern New South Wales; northeastern Victoria, and southeastern Tasmania.
Rainfall totals between 50 mm and 100 mm were recorded in northern Western Australia, much of the Top End of the Northern Territory, the far north of the Cape York Peninsula, and in eastern Queensland. Similar totals were recorded in large areas of central and southern New South Wales, much of the eastern half of Victoria, and most of Tasmania.
Rainfall totals between 10 mm and 50 mm were recorded in areas along the west and south coasts of Western Australia and remaining parts of the Kimberley; in the Top End and Gulf Country and southern interior of the Northern Territory; and the southern half and central north of South Australia. Similar totals were recorded in western Victoria, remaining parts of New South Wales, remaining areas of Tasmania, and in eastern and southern Queensland.
Little or no rainfall was recorded in the Pilbara and much of the central interior of Western Australia, northeastern and northwestern South Australia, parts of the southeast and southwest of the Northern Territory and southwestern Queensland.
Impact of recent rainfall on deficits
The Drought Statement, issued on 3 November 2017, discusses rainfall deficits over Australia for the 8-month (March 2017–October 2017) and 5-month (June 2017–October 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 6- and 9-month periods ending 5 December 2017.
Rainfall for the period 1 June 2017 to 5 December 2017
Serious to severe deficiencies are present at the 6-month timescale across an area of southern Australia extending along the coast from the Eucla District in Western Australia, into the northern Eyre Peninsula and southern pastoral districts of South Australia, then across large areas of southern New South Wales, reaching north into the Central Tablelands and western slopes of the Great Dividing Range, and south into East Gippsland in Victoria.
Serious to severe rainfall deficiencies are also present along the east coast of Tasmania and in areas along the coast of Western Australia in the Gascoyne and Pilbara.
Rainfall in the last week has eased deficiencies somewhat in southern pastoral districts of South Australia and some areas of inland New South Wales, and to a lesser extent in parts of the coastal southeast.
Affected areas in southern Australia have generally received less than 60% of average rainfall for the period, although parts of eastern and southwestern New South Wales and southern pastoral areas of South Australia have observed lower totals, less than 50% of average in more northerly parts of the affected region in South Australia. Totals are also similarly low right against the east coast of Tasmania.
In affected areas of the Gascoyne District in Western Australia, rainfall has generally been less than 60% of average, while some parts of the Pilbara have received less than 20% of average.
Rainfall for the period 1 March to 5 December 2017
Serious to severe rainfall deficiencies persist at the 9-month timescale along the west coast of Western Australia between about Exmouth and Perth, areas of coastal South Australia between the Nullarbor and Eyre Peninsula, East Gippsland in Victoria, and across the extreme east coast of Tasmania. Some isolated pockets of serious deficiencies persist in the Alice Springs District of the Northern Territory, southwestern to central Queensland, and western New South Wales. Rainfall during the past week has slightly eased deficiencies between Ceduna and the Eyre Peninsula in South Australia.
Rainfall in the last week has somewhat eased deficiencies in southern South Australia, eastern Victoria and east coast Tasmania.
The west coast of Western Australia has received up to 70% of average rainfall for the period, although an area around and inland of Exmouth has received less than 30% of average rainfall. Affected parts of South Australia, Victoria, and Tasmania have generally received less than 70% of average rainfall for the period.
Product code: IDCKGRWAR0