We have the combination of a strong nIOD (-ve) and a Clayton’s La Niña.
Models predict this nIOD (-ve) will take until late November to collapse, which is a bit longer lived than most IOD events of late.
The cloud patterns, SOI pressure patterns, trade winds and undersea are all in the La Niña camp, but the NINO3.4 ocean surface is not interested.
Ocean temperatures to the north of Australia are looking La Niña like, even though models now think a proper La Niña is unlikely.
The Southern Annular Mode was strongly positive for the month, assisting rainfall in the east of Victoria, it has currently dropped to more normal levels.
This might see a return of more frontal systems for southern Victoria.
Pressure patterns have been conducive to rainfall trigger passage and their strength.
The Sub Tropical Ridge of high pressure has been much higher than a normal winter position allowing lows and fronts over the state.
There has been much lower pressure for the last month indicating many rainfall triggers passing by.
Pressure is now lower at Darwin, which makes it easier to get moisture down to Victoria.
Model outlooks for the rest of the year are for average to slightly wetter rainfall and temperature predictions are remain mixed.
●For more ‘‘The Break’’ analysis, go here http://bit.ly/2cRDMPS
— Dale Grey, seasonal risk agronomist, Agriculture Victoria, and author of ‘‘The Break’’ (September)