Issued on 6 May 2010

Short-term deficits persist in Western Australia

Above average rainfall continued across the northern and central third of Australia during April 2010. For the Murray-Darling Basin (MDB) averaged as a whole, it has been the sixth wettest start to the year since records began in 1900, while Victoria continues its wettest start to the year since 1974. However, short-term deficiencies still remain in Western Australia. While recent rainfall has cleared a number of short-term rainfall deficiencies across eastern Australia, serious deficiencies remain on time-scales longer than two years and continue to affect water supplies; to alleviate these would require above average rainfall for a sustained period. This is especially true for the very long-term deficiency periods of 8 and 13 years (see the drought statement archive). Rainfall has been below average across much of southwest and southeast Australia since 1997, whilst central and southern parts of the MDB have experienced below average rainfall since 2002.

13-month rainfall deficiencies

Below average falls over the western half of WA during April 2010 exacerbated areas of rainfall deficiency in WA as described in the previous drought statement. For the 13-month period from April 2009 to April 2010, serious to severe rainfall deficiencies remain evident over much of the central WA coast reaching inland, covering much of the Pilbara and Gascoyne districts, where they have intensified to some extent. Serious to severe rainfall deficiencies also remain evident over the Southeast Coastal and eastern parts of the Great Southern district.

Whilst recent rains in eastern Australia have provided, in many cases, short-term relief, sustained periods of above-average rainfall are needed to remove these very long-term deficiencies. These long-term deficiencies have taken place against a background of well above average temperatures including Australia's warmest decade on record. Further information on exceptional rainfall and temperature events across Australia can be found in the Special Climate Statements.

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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.

Archives

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