The air mass is the cold air pressing in not the prefrontal airmass which is why there is a lot of ice being shown especially with the multiple piece setup it is showing.
Week 1 Blowtorch
Week 2 near to slightly above normal.
Week 3 same only cooler than normal to the north and west
Week 4 same
Week 5 and beyond dartboard.
One thing that is consistent, it gets cold out west and stays that way through the duration.
I couldn't find climatology for thickness records, but 500mb heights I did find, and that would have been near historic. The lowest heights I found for Melbourne was 544dm and 550dm for Miami. This was 547 and 550 exactly.