Updated on 6 May 2015
A dry finish to the northern wet season increases deficiencies in northern Australia
April rainfall was above average for much of the mainland southeast, except for central to western Victoria, where rainfall was generally near-average. Rainfall was also above average across much of western to central Western Australia. Rainfall was below average for large areas of the north of both the Northern Territory and Queensland, and very much below average in Tasmania, which had its fifth-driest April on record. All but the eastern third of Tasmania received April rainfall in the lowest 10% of historical observations (decile 1).
April also concluded the northern wet season for 2014–2015 (the northern wet season spans October–April). October and November saw a slow start to the northern wet season, and despite a generally good peak over December and January, the final three months brought a very dry finish. 3-month rainfall for February–April 2015 was below average for Queensland, the Northern Territory, northern to central South Australia, the Kimberley, and a strip along the eastern border in Western Australia. For northern Australia (defined as the region north of the South Australia–Northern Territory border), February–April 2015 was the eighth-driest on record, with 29% of northern Australia experiencing rainfall in the lowest 10% of historical observations (decile 1). Long-term deficiencies in Queensland are now a result of three consecutive poor wet seasons.
Monthly rainfall over the southeast of South Australia through western Victoria, and across western Tasmania has been below average from August last year (apart well-above-average January rainfall, and above-average March rainfall in Tasmania). Serious or severe rainfall deficiencies have been observed in parts of these regions for various medium-term periods since late 2013. Longer-term deficiencies are also evident for various periods under 2 years duration in much of this region, and deficiencies are also evident over large areas of eastern Australia for periods of about 3 years duration. The Bureau will continue to closely monitor how the autumn season progresses in southeastern Australia.
10-month rainfall deficiencies
Compared to the previous Drought Statement, the spatial extent and severity of rainfall deficiencies for the 10-month period (July 2014 to April 2015) have increased across the Cape York Peninsula in Queensland and in western Tasmania, while good rainfall during April has eased deficiencies somewhat in parts of coastal South Australia from the Mount Lofty Ranges westward. Rainfall deficiencies in southeastern South Australia and western Victoria remain largely similar to the preceding 9-month period, although easing in northwestern Victoria.
The area experiencing severe or serious deficiencies (lowest 5% or lowest 10% of records) covers the central West Coast District of South Australia, a region of the pastoral northwest of South Australia, and the York and Fleurieu peninsulas; a region spanning southeastern South Australia and much of western Victoria, although generally not reaching the New South Wales border; parts of western and northwestern Tasmania; and areas of northern Queensland near Townsville, the central to western Cape York Peninsula, and along the southern coast of the Gulf of Carpentaria.
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31-month rainfall deficiencies
At the 31-month timescale (October 2012 to April 2015), rainfall deficiencies have slightly increased in severity across northern and central inland Queensland. Deficiencies have also increased in small pockets of coastal western Tasmania. Elsewhere, deficiencies remain similar to those for the preceding 30-month period.
Severe and serious deficiencies are in place in a broad area extending from south of the Cape York Peninsula, through central and western Queensland, into the areas of central southern Queensland and northern New South Wales inland of the Great Dividing Range. Deficiencies are also in place in an area stretching from southeastern South Australia and western Victoria, away from the coast, to just over the border into southern New South Wales, with a small pocket also around the northeast of Melbourne, as well as in small areas on the west coast of Tasmania.
Deficiencies also persist at a range of even longer timescales. For the 36-month (three-year) period rainfall deficiencies remain in similar, but somewhat more extensive, areas to those affected at the 31-month timescale.
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Soil moisture
Soil moisture in the upper layer for the week ending 26 April had increased, compared to the week ending 29 March, across southern mainland Australia and along the central coast and southeast of Queensland, but decreased in Tasmania.
Upper layer soil moisture at the end of April was below to very much below average across the north of the Northern Territory, much of western Queensland and areas of the Cape York Peninsula, extending south to about Townsville, and across parts of northwestern and central Tasmania. Soil moisture was above average across most of Western Australia, southern and eastern South Australia, but not the southeast, most of New South Wales, and also across eastern Victoria.
Lower layer soil moisture for the week ending 26 April was generally similar to the week ending 29 March, decreasing slightly across most of Queensland and the Top End, while increasing slightly across much of Western Australia and the coastal southern mainland.
Lower layer soil moisture was above average for most of Western Australia, much of the Northern Territory, a small area of eastern Queensland, an area spanning southern South Australia and western New South Wales, an area covering East Gippsland in Victoria and far southeastern New South Wales, and parts of Tasmania. Soil moisture was below average in Western Australia for the northern half of the South West Land Division, extending just into the Goldfields District, areas of coastal northern Queensland, inland central Queensland, and an area inland of the Great Dividing Range spanning the border between Queensland and New South Wales, as well as small areas of southern New South Wales, much of central to western Victoria, and southeastern South Australia.
