A low pressure system over Western Australia today will be the start of the next big system to affect eastern Australia.
It will move through the southeast on Friday, with some rain as it goes. But that's not the main event. The upper level energy will be pushed up over the interior and meet up with a feed of tropical moisture from the Indian Ocean. This will all progress eastwards, and when it reaches the warm Tasman Sea, the next East Coast Low (ECL) may form.
SATURDAY - affects southern Queensland and northern New South Wales
SUNDAY - affects much of the eastern states between about Townsville and East Gippsland
MONDAY - affects eastern New South Wales and Victoria
before moving away...
Much of this area already has considerably water-logged ground from the last system, and flooding will be a concern. The worst spots for damaging winds and dangerous surf will depend on the actual path of the low - but guidance shows that Tasmania could miss out on most of the rain this time. The latest watches and warnings will be available at the Weather Bureau: http://www.bom.gov.au/australia/warnings/index.shtml
East Coast Low's are a regular occurence - 2007 saw five of them in June, most while I was on shift as a forecaster at the Sydney Weather Bureau.