A substantial late-autumn rain event will affect Australia's eastern states and territories during the second half of this week. A low pressure system and associated trough crossing the country from west to east this week will generate widespread rain and storms. Another trough forming over eastern Queensland will contribute to the deluge. Rainfall will be heavy enough to cause flooding in some parts of the county and severe thunderstorms are also likely. The initial phase of this event will affect parts of Western Australia and South Australia during the first half of the week. Showers and thunderstorms will develop over southwestern districts of Western Australia today, including Perth. Wind gusts may reach 80-90km/h at times along exposed areas of the lower west and southwest coasts, although severe weather is otherwise unlikely. Conditions will ease this afternoon and tonight as the low moves further east. Showers and thunderstorms will affect South Australia from Tuesday to Thursday as the trough and trailing low slowly move over the state. Three-day rainfall totals will be in the 5-10mm range for parts of the Agricultural Areas and lower pastorals, although heavier totals may occur in some areas, particularly with thunderstorms. More widespread and substantial rainfall will develop over Australia's eastern states during the second half of the week. The bulk of the rain will fall between Thursday to Saturday, when widespread totals in excess of 20mm are likely in Queensland, New South Wales, inland Victoria and northern Tasmania. Some areas will see more than 50mm and isolated totals above 100mm are likely in some places. This will be the heaviest rain in at least two months for large swathes of eastern and southeast Australia. This system is on track to produce the heaviest rain since cyclone Debbie for central Queensland, where computer models suggest more than 100mm will fall by Saturday. This would be enough rainfall to cause flooding in the region. The Murray Darling Basin will pick up some notable rainfall too. Three-day totals of 20-40mm expected in parts of western New South Wales and northern Victoria. Thunderstorms are likely to develop in multiple states as this system move across the country. The greatest risk of severe storms will be in the east during the second half of the week as atmospheric moisture and instability increase. Keep up to date with the latest severe weather, flood and storm warnings as they are issued throughout the week.