Drought Statement - Issued 4th October 2007


drought_text.html

For the 4, 5 and 12-month periods ending 30th September 2007

Rainfall deficits worsen following a dry September

LINKS:
rainfall deficiencies definition
4-month rainfall deficiencies
5-month rainfall deficiencies
12-month rainfall deficiencies

Rainfall deficits have expanded and intensified over the southern half of the country as a result of widespread below to very much below average September rainfall. Averaged over the Murray-Darling Basin (MDB), it was the driest September in the historical record back to 1900. Unless October and November are wetter than average, 2006-07 will be one of the very few instances in history where the MDB has suffered a winter-spring drought in successive years. The other years when this has occurred were 1918-19 (the latter was extremely dry), and 1940-41, with 1940 being very dry. In each of the years 1927, 1928, and 1929, large parts of the MDB had a winter-spring rainfall total in decile 3 or lower, although individually none of the years was extremely dry.
See September rainfall pattern

Since the start of winter, South Australia has been the worst hit state, with the four-month average being the lowest on record at just 26 mm. At the yearly time-scale, rainfall deficiencies are evident in all states and territories, although the NT has only a few small patches. As September 2007 had generally similar rainfall to September 2006 in the areas with twelve-month deficiencies, there was little change to their pattern compared with the situation at the end of August.

For the 3-month period from June to September 2007, an area of serious to severe rainfall deficiencies covered most of SA, southwest Queensland, western NSW, northern Victoria, regions in the southern NT, scattered parts of WA and a small patch in northeast Tasmania. Several regions had record low totals, most notably in SA, Queensland and New South Wales.

Rainfall deficiencies for the 5-month period from May to September 2007 were widespread across the southern half of Western Australia. SA was also affected, but to a much lesser extent than for the four-month period.

For the 12-month period from October 2006 to September 2007, zones or regions of rainfall deficits existed near the southwest and west coasts of WA (generally south of Shark Bay), along parts of coastal SA, in northern and eastern Tasmania, in a band from south-central Victoria to the tablelands and western slopes in southeastern NSW, and in southeast Queensland and adjacent parts of far northern NSW. Record low falls for this particular 12-month period were recorded just to the east of Melbourne, and along WAs west coast between Shark Bay and Geraldton.

The deficiencies discussed above have occurred against a backdrop of multi-year rainfall deficits and record high temperatures that have severely stressed water supplies in the east and southwest of the country. Several years of above average rainfall are required to remove the very long-term deficits. Furthermore, the combination of heat and drought during the past five to ten years over the MDB and southeastern Australia, is outside the typical range of variability experienced during the previous 100 years.

Rainfall deficiency maps for standard periods out to three years are available.


Note: The terms used to describe rainfall in these Drought Statements have the following meanings -

Serious deficiency - rainfalls in the lowest 10% of historical totals, but not in the lowest 5%
Severe deficiency - rainfalls in the lowest 5% of historical totals
Lowest on record - lowest since at least 1900 when the data analysed begin

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 more information regarding this rainfall deficiencies statement, please contact the following climate meteorologists in the National Climate Centre:

Grant Beard on (03) 9669 4527
Andrew Watkins on (03) 9669 4360
Lyn Bettio on (03) 9669 4165

External Sites Relating to Drought

The Bureau of Meteorology does not make formal drought declarations as these are done by either the relevant State Governments or by the Australian Government. The Australian Government Program is called Exceptional Circumstances and it is administered by the Federal Department of Agriculture, Fisheries and Forestry (DAFF). General information about Australian Government drought assistance is available at http://www.daff.gov.au/droughtassist.



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Click on the map for full resolution.
A black and white version is also available.

Click on the map for full resolution. height="453" width="660"
Click on the map for full resolution.
A black and white version is also available.