Widespread showers and thunderstorms will affect Australia’s southeastern states and territories during the second half of this week.

An upper-level cut-off low pressure system will drift across southeastern Australia between Thursday and Sunday. This isolated pool of cold air, which has ventured north from the Southern Ocean, will produce a five-day spell of rain and storms in parts of SA, Victoria, Tasmania, NSW and the ACT.

The cut-off low, which is located about 5-6km above the ground, will drift over South Australia on Thursday, linger near the NSW-Victoria border on Friday and Saturday, then drift south towards Tasmania on Sunday. The low is expected to move out into the southern Tasman Sea on Monday.

As the cut-off low meanders over southeastern Australia, the atmosphere will become more unstable, leading to lots of cloud, rain and storms.

On Wednesday, isolated showers and thunderstorms will develop across large swathes of Victoria, NSW, SA and central Australia, ahead of the approaching upper-level low.

As the upper-atmosphere starts to become cooler on Thursday, showers and storms are expected to become more organised and heavier, targeting central and eastern districts of SA, much of Victoria and NSW, and parts of Tasmania and Queensland.

Showers and thunderstorms will continue in parts of Victoria, NSW, SA, Tasmania and Queensland on Friday and Saturday, before easing for many areas on Sunday and mostly clearing by Monday.

Severe thunderstorms and heavy rain are likely in multiple states and territories during the second half of this week, with flooding, damaging winds and hail all a risk.

Rainfall totals from this event are difficult to predict and will depend largely on the location and intensity of thunderstorms. Some places could receive more than 100mm by the end of Sunday, while other areas could see less than 10mm.

Visit http://www.weatherzone.com.au/warnings.jsp for the latest warnings.