Cold front isn't due to reach the far southwest corner of the state until about 10-11pm tonight. It should then speed up slightly and reach Melbourne around 2-3am and exit the far east of the state by late morning. As many have mentioned, the eastern central districts and also western Gippsland should do quite well out of this system, around 20-40mm for those areas. Elsewhere, generally 10-20mm. Not likely to see much rainfall until it develops from the west later tonight and early tomorrow morning. Also, expect these rather strong northerly winds to continue this afternoon before the strong southwesterly change brings strong to gale force winds but a little delayed from the front, particularly to coastal areas and a return to winter!
Hasn't really been mentioned, but there is the chance of both surface and mid level thunderstorms with the frontal feature itself, particularly for areas on and south of the ranges. Starting in the west tonight, in the rain band mid-level storms will be possible, whilst just ahead of and with the front surface-based storms will be possible. There is also a risk that these surface-based storms may generate strong winds, heavy rainfall and even large hail if they develop under the current forecast environment. Will be one to watch although I suspect if anything develops, since they will happen overnight, most people will be asleep. There's a slightly more significant risk of thunderstorm development during the late morning over eastern districts though. Unfortunately I cannot get the chart up until tonight, so you'll just have to stick with me until then.
Interesting night and day ahead! Good luck on the falls everyone!
EDIT: Just saw John's post ... basically sums it all up!