Issued 2 August 2006

Rainfall deficiencies spread in western WA; ease in central and eastern Australia

Rainfall deficiencies expanded along the west coast of WA following yet another month with very much below average rainfall in July, the Bureau of Meteorology announced today. However, above average July totals largely removed rainfall deficits that were evident in central Australia at the end of June, and near-average July rainfall was sufficient to ease the deficits in central and southeast New South Wales.

5-month rainfall deficiencies

For the 5-month period from March to July, a large part of western WA from Albany to north of Carnarvon is affected by severe rainfall deficiencies, with a broad coastal zone from Cape Leeuwin to north of Geraldton experiencing record low rainfall. July rainfall was in the driest one-tenth of the historical record (decile 1) over much of western WA from Perth northwards, with record low totals close to Carnarvon. This is the third consecutive month with very much below average rainfall (decile 1) across a significant part of western WA.

A band of rainfall deficiencies, generally in the severe category, runs from central Victoria northeast to the central-west of NSW, where average July falls eased the deficits evident at the end of June. The other areas affected for this period are western Victoria and the adjacent parts of southeast SA, some of northern and southeast Tasmania, and southeast Queensland.

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7-month rainfall deficiencies

For the 7-month period from January to July, similar areas are affected, though generally to a lesser extent. Tasmania is the notable exception: rainfall deficiencies dating from the start of the year affect much of the north and east of the State, with a small area of driest on record on the north coast. The deficits in south Queensland are also more extensive than for the five-month period.

Rainfall deficiency maps for longer periods indicate that deficiencies at the three year timescale, which are particularly relevant to water supplies, remain prevalent in parts of eastern Australia, especially in Queensland.

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Black and white | High resolution colour

Definitions

Lowest on record - lowest in the historical analysis, which runs from 1900.
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.

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