Models very rarely handle anything of a tropical origin (like heavy moisture or a tropical low) when it is moved across southeast Australia, especially Victoria. It's just one of those things where we have to wait until a couple of days before, or even the day before, to get the more specific details, like where the best totals will be etc ... it was a very tricky first system in-terms of having to forecast it. I don't blame the BoM for getting it wrong, but they have been a little topsy turvy on updating their public forecasts to reflect model changes, whereas behind the scenes they were questioning quite a few things. I liked it when they updated their forecasts more than twice a day ... the good old days
This next low pressure system looks pretty good to me as well. Potentially getting as deep as 994 hPa. Hooks into the moisture over the southeast that has been left over from the weekend, and should provide relatively healthy falls between 10-25mm widespread. I agree with others, the Wimmera and parts of the west could do the best out of this system with higher totals up to 40-50mm according to the US and local models. The EC does have those high falls in those parts too but extends some of it over central districts (including parts of Melbourne). Timing of the system looks similar on all models with rain not likely to really extend from the west until into Tuesday.
Here in Brighton currently, a lovely warm breeze but damn humid!