How it works
This is a shorter time scale - the next few weeks. No longer about 'feeds of moisture', SAM influences our weather systems - the lows, troughs and fronts that turn that moisture into rain.
"Negative" generally helps it rain in far southern Australia, as the cold fronts can be stronger and move further inland.
"Positive" generally helps it rain in NSW/QLD, and northern parts of VIC, as troughs and wandering lows are more likely to feature.
But highs separate these - and if one of these sits in the wrong spot for your location, it won't rain no matter what the signal is.
Trend for the future