Rainfall deficiencies persist in Tasmania, emerge near the west coast of Western Australia
May rainfall was below to very much below average across much of Western Australia, with large areas along the west coast and in the interior in decile 1 (lowest 10% of historical observations). Rainfall was also below average for large areas of South Australia in the west, south, and central east; northwestern New South Wales; and for much of Victoria away from the west, northern country, and far east. Following below average rainfall near the west coast of Western Australia in April, deficiencies are now emerging.
The Northern Territory, the northern Kimberley, and parts of northwestern to central northern Queensland also observed below average rainfall for the month, but May forms the first month of the dry season for northern Australia, and average rainfall is typically low for the months May to September. While areas of southwestern Queensland and the southeastern Northern Territory experienced a dry end to the wet season; significant rainfall totals are not likely before the return of the wet season.
3-month rainfall deficiencies
The west of Western Australia has experienced below average rainfall for both April and May, seeing the emergence of serious and severe rainfall deficiencies for the 3-month period in a broad area between Exmouth and the region north of Perth. Serious rainfall deficiencies have also emerged in pockets of the southern South West Land Division in Western Australia and on the Eyre Peninsula in South Australia. The Climate Outlook for June to August indicates that a drier than average winter is likely across the south of both Western Australia and South Australia.
In Tasmania rainfall deficiencies remain at the 3-month timescale, covering the western highlands region.
Soil moisture in the lower layer (from 10 cm to 100 cm deep) decreased for May compared to April across the west and south of Western Australia, the Northern Territory, western Tasmania, and eastern New South Wales. Soil mositure increased across the interior of Western Australia and central South Australia.
Soil moisture for May was below average for the South West Land Division, western Gascoyne and western Pilbara in Western Australia; the Eyre Peninsula and pockets around Gulf St Vincent in South Australia; western and southern Tasmania; and a large area extending through the southeast of the Northern Territory and Queensland's west and the Maranoa and Warrego district.
Soil moisture for the month was above average for most of the Kimberley and the interior of Western Australia; the Top End and adjacent north of the Northern Territory; the south of the Cape York Peninsula in Queensland and an area of the east coast extending from around Townsville in northern Queensland to northeastern New South Wales; western and southern Tasmania; and across an area extending from central South Australia through the southwest of New South Wales and the western half of Victoria.
- May rainfall was below average for most of Western Australia, large parts of South Australia and Victoria, and northwestern New South Wales
- Serious to severe rainfall deficiencies are present at the 3-month timescale near the west coast of Western Australia, the Eyre Peninsula in South Australia, and the western highlands of Tasmania
- Soil moisture is below average across the west of Western Australia, much of inland Queensland and western parts of the Northern Territory, the Eyre Peninsula in South Australia, and western 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 20 June 2017, rainfall was recorded in parts of Western Australia covering the west Pilbara coast, inland Gascoyne, and the southwestern quadrant of the State; the central and north coast of New South Wales, the southeast and north tropical coast of Queensland, and across western Tasmania. Some light falls were recorded in the southeast South Australia, as well as the northwest and southern Victoria.
At the start of the week, a moist onshore flow in the wake of an eastward moving offshore low produced moderate rainfall in coastal areas of Queensland's north tropical and southeast, and the far northeast of New South Wales. A trough near the west coast and associated cloudband, combining with a trough from the northwest coast, moved through western and southern Western Australia at the beginning of the week, producing light to moderate rainfall in west Pilbara coastal areas, inland Gascoyne, and the southwestern quadrant of Western Australia.
By mid-week, the cloudband over Western Australia had moved east and dissipated over the southeast of the continent, producing only light rainfall in the southeast South Australia, and northwest and southern Victoria.
During the second half of the week, a trough located off the New South Wales coast and moved slowly eastward, with an associated low pressure system which developed once well offshore. Rainfall was recorded on the north coast of New South Wales and far southeast Queensland, followed by moderate falls on the central coast of New South Wales.
Two weak cold fronts brushed Tasmania during the week producing rainfall over the western parts of the State. A weak cold front approached southwest Western Australia at the end of the week, bringing light to moderate fall in the south coast.
Rainfall totals between 50 mm and 100 mm were recorded in a few locations in the south coast of Western Australia, and small areas in the central and north coast in New South Wales, and southeastern Queensland. Totals exceed 100 mm in isolated spots in the far north coast of New South Wales and the tip of the southeast Queensland. The highest weekly rainfall total of 247 mm was recorded at Point Lookout on Stradbroke Island in Queensland.
Rainfall totals between 10 mm and 50 mm surrounded higher falls along the central and north coast in New South Wales and southeast Queensland, as well as the Cape York's east coast around Cooktown. The northwest Tasmania, and several areas in Western Australia including the west Pilbara coast, inland Gascoyne, west coast and south coast also recorded between 10 mm and 50 mm rainfall.
Little or no rainfall was recorded in most of the northern half and central Western Australia, most of South Australia, the Northern Territory, most of Queensland away from the southeast and north tropical coast, most of New South Walesaway from the central and north coast, most of Victoria, and eastern Tasmania.
Impact of recent rainfall on deficits
The Drought Statement, issued on 5 June 2017, discusses rainfall deficits over Australia for the 3-month (March-May 2017) period. The rainfall deficit map is available for this period as well as for standard periods.
The map below shows the percentage of mean rainfall that has been received for the rainfall deficit period for the 3-month periods ending 20 June 2017.
Serious to severe rainfall deficiencies are present at the 3-month timescale near the west coast of Western Australia, the Eyre Peninsula in South Australia, and the western highlands of Tasmania.
Compared to last week, rainfall deficits have increased slightly in each of the areas affected. Rainfall received for the period was less than 50% of average for the affected areas in Western Australia, dropping to less than 30% of average in the Gascoyne and Central West districts, less than 30% of average for the Eyre Peninsula in South Australia, and less than 70% of average for western Tasmania.
Product code: IDCKGRWAR0