The SAM has been strongly positive through June, pushing moisture into eastern Australian productive agricultural areas. The guidance below expects the SAM to retreat back into neutral levels, so it looks unlikely to influence our climate in the next fortnight at least.

Now we are in winter its time to start monitoring the SAM again. When the SAM is negative, winds from Antarctica blow further north up into southern Australia. When the SAM is positive, these winds pull back towards Antarctica, allowing moisture from the tropics to push into Qld and NSW. The SAMs main influence is in spring and summer, but it is worth keeping an eye on to help us ground-truth model guidance when we see a change. A really good video at the bottom of this article will help explain this a little better.

Antarctic Oscillation or SAM values (2 July)

Recent research by Hendon et al, (2014) at the Centre for Australian Weather and Climate Research found the Southern Annular Mode to be the leading mode of circulation variability through parts of inland eastern Australia where cotton is grown; particularly in the spring planting period.
 
A positive SAM has been proven to increase moisture supply into fronts and troughs forming in eastern Australia. The chart provided by Climate Prediction Center (US) shows the most recent observations of the SAM or (AAO). 

A negative SAM traditionally leads to a dry westerly circulation pattern through eastern Australian cropping areas.
 
BOM researchers Lim and Hendon (2013) found the SAM has the strongest connection with El-Niño Southern Oscillation in October and November – whereby the SAM is influenced most by El Niño or La Niña conditions.

Growers and advisors are encouraged to monitor the phases of the SAM together with seasonal forecasting, multi-week and short term weather models during planting. A short cartoon explaining the SAM can be found HERE.