A north west tropical in-feed of moisture from the Indian ocean gives some moisture to a low forming on the s/west corner of WA on Sunday the 25th August
High pressure over the rest of the mainland
That same low tracks across the Bight and may give western VIC some showers on Tuesday as the perimeter of the low passes
On Tuesday the 26th the low pressure belt spawns another low for s/west WA
Some decent rain and storms a distinct probability.
This is a colder cored low formed from southern ocean air.
This same closed low travels along the southern mainland of SA on Wednesday and possibly VIC by Thursday..
The chance of rain and storm activity would be likely if this were to eventuate