If the energy on the backside is pressing in too fast it can end up sheared out. Along with if there is too strong of a ridge being formed out west behind the system.
Way too much Bustardi talk in this thread, dude is trash and has been for years. Not worth even acknowledging anymore with his clearly biased approach.
The big takeaway from that post to me is the MJO, at the very least with a high amplitude wave, we are going to flush out the current pattern at the very least.
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.