Autumn rains fail; severe deficiencies widespread in the southeast

For the 5-month period from January to May, severe rainfall deficiencies have emerged over the southern half of NSW, the ACT, northern and central Victoria and southeast and south-central SA, while serious deficiencies are evident in a few small patches in the southwest of WA. Patches of lowest on record falls have occurred near the Murray River between Swan Hill and Renmark, as well as in the Victorian Mallee and adjacent Murray Lands in South Australia. It is also worth noting that serious deficiencies for the March to May period exist in southwest WA in an area roughly bounded by Wandering, Jerramungup, Albany and Denmark.

The impact of the low rainfall has been intensified by very much above average (highest 10%) or record high maximum temperatures since the start of the year. For example, averaged over the Murray Darling Basin, the mean maximum temperature for the year to date is about 1.5 degrees above average, some 0.2 degrees above the previous record set in 2001.

For the 23-month period from July 2002 to May 2004, rainfall deficiencies still persist in the southeast of the mainland, in an area, which although smaller than that affected by 5-month deficiencies, largely overlaps with it. However, this longer period affects areas further south including Gippsland, and the Central district surrounding Melbourne. A large part of the NSW Southern Tablelands has had record low falls for the 23-month July to May period. In WA, long-term rainfall deficiencies are evident in a relatively small patch near Exmouth and Onslow, as well as in a very small area near Busselton.