Updated on 5 February 2015
Rain brings some relief in Queensland, reduces deficiencies in northwestern Victoria
Rainfall during January was below average for much of the Cape York Peninsula and parts of the west of Western Australia, particularly in the central south. Monthly rainfall was above to very much above average (highest ten per cent of records) in a broad band extending from the Kimberley in Western Australia, through the Northern Territory and covering most of southeastern Australia as well as smaller parts of eastern and western Queensland. This rainfall has moderated deficiencies in northwestern Victoria and adjacent areas and, to a lesser degree, moderated deficiencies in central northern and inland Queensland as well.
Rainfall across most of southeastern Australia, but excluding West and South Gippsland and central southern Victoria, was more than one and a half times the long-term January average. Totals were more than three times the January average in areas of the eastern half of South Australia and parts of adjacent western New South Wales. It should be noted, however, that January and February are climatologically the driest months throughout much of this region, and the unseasonable January rainfall was not high enough to clear rainfall deficiencies between western Victoria and the central West Coast district of South Australia. These deficiencies are strongly influenced by very dry conditions between August and October 2014. Maximum temperatures were also very much warmer than average (in the highest ten per cent of observations) across southern Australia during this period.
7-month rainfall deficiencies
For the 7-month period (July 2014–January 2015), above-average January rainfall across much of southeastern Australia has significantly reduced rainfall deficiencies in northwestern Victoria and adjacent parts of southern New South Wales and inland southeastern South Australia. Rainfall deficiencies across the south of the Cape York Peninsula, the Top End and northwestern Tasmania have also been reduced.
Serious or severe deficiencies (lowest 10% to lowest 5% of records) remain across much of the Cape York Peninsula and a small area of Queensland's north coast near Townsville, in the northwestern tip of Tasmania, extending between southwest Victoria and the central West Coast district of South Australia, and in parts of the coastal Pilbara and Gascoyne in Western Australia. Deficiencies on the west coast of Western Australia have increased in size compared to the previous Drought Statement.
14-month rainfall deficiencies
The area affected by serious and severe rainfall deficiencies for the mid-range 14-month period (December 2013–January 2015) has also been substantially reduced in western Victoria, southeastern Queensland and northeastern New South Wales. Although areas of serious and severe rainfall deficiencies persist in inland southwestern Victoria and adjacent parts of South Australia as well as pockets of coastal Tasmania, northeastern New South Wales, and northern and southeastern Queensland this period has been removed from the Drought Statement. The Bureau will however continue to monitor deficiencies at this timescale.
28-month rainfall deficiencies
At the 28-month (October 2012–January 2015) timescale, rainfall deficiencies have also been reduced across much of northern Queensland and adjacent parts of the southeastern Northern Territory and northeastern South Australia. Nevertheless, serious or severe deficiencies persist across much of northern Queensland away from the coast and a large area inland of the Great Dividing Range spanning the border of Queensland and New South Wales.
Deficiencies also remain, despite being lessened, in much of central western Victoria, crossing just into southeastern South Australia. On the coast of the Gascoyne district in Western Australia deficiencies remain largely unchanged compared to the preceding 27-month period.
Long-term deficiencies in Queensland are largely the result of below-average rainfall over the 2013–14 and 2012–13 'summer' wet seasons (the northern wet season spans October–April). With only three months to go in the current wet season, February–April rainfall would need to be above to very much above average to bring rainfall totals for October 2012–April 2015 out of the lowest ten per cent of records for similar periods. For much of the affected region in western Victoria, southeastern South Australia, and the region inland of the Great Dividing Range in northern New South Wales and southern Queensland the required totals would be in the highest ten per cent of records for February–April rainfall.
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.
The current drought in Queensland is comparable to the 2002–2003 drought, which was perhaps more severe in terms of rainfall deficiencies that occurred at times over a very large area. Historical data shows that the current drought is perhaps a one in ten or twenty year event over a significant part of inland eastern Australia (see for example the 24-month deciles map for 2013–2014), but very severe in some places. For some locations in central Queensland the present deficiencies are the most severe on record, and have been accompanied by record high temperatures. See: 24-month maximum temperature deciles map for 2013–2014.
Compared to last month, upper layer weekly soil moisture for the week ending 25 January has increased across eastern Australia and decreased in the west. Upper layer soil moisture was very much above average across the Kimberley, most of the Northern Territory, between Queensland's Gulf Country and northeastern New South Wales, and broadly across eastern South Australia, the southwestern half of New South Wales, most of Victoria, and most of Tasmania. Soil moisture was below average for most of Western Australia south of the Kimberley and parts of western South Australia.
Compared to last month, lower layer weekly soil moisture for the week ending 25 January has increased across parts of the north and east of Australia. Lower layer soil moisture was above average for most of the eastern half of Western Australia, much of the Northern Territory, the Gulf Country and west of the Cape York Peninsula, for central eastern Queensland, southern South Australia and parts of western New South Wales, and for an area covering East Gippsland in Victoria and far southeastern New South Wales. Soil moisture was below average in much of a 400 km wide strip along the west coast of Western Australia, a large area of southeastern Queensland and northeastern New South Wales, a smaller area on Queensland's north tropical coast, and across southeast South Australia, most of Victoria except the far east and parts of southern New South Wales.