A prolonged spell of stormy weather will affect Australia's eastern states during the second half of this week. A slow moving low pressure trough that has produced daily showers and storms in western and central Australia during the past week will start to move across eastern Australia from today. The eastward-moving trough will interact with a feed of tropical moisture and an upper level low pressure system to generate widespread showers and thunderstorms in parts of Queensland, NSW, the ACT, Victoria and SA between now and Sunday. On Wednesday, most of the showers and storms will occur near the trough in western parts of Queensland, NSW and Victoria and eastern districts of SA. The heaviest falls are likely to occur near the upper low in western Victoria during the afternoon and overnight. The impending deluge has prompted a severe weather warning for flash flooding in Victoria's Mallee, Wimmera and South West Districts. During Thursday and Friday, the near-stationary upper low will continue to produce rain in western Victoria as the slow-moving trough causes showers and storms to spread across NSW, the ACT and Queensland. There is potential for parts of western Victoria to amass more than 100mm of rain by Friday night, although most of this will fall by Thursday evening. On the weekend, the upper low will move towards the northeast, causing showers and thunderstorms to continue over a large swathe of NSW and Queensland, while conditions start to ease in Victoria. Rainfall totals from this system are difficult to predict for Australia's eastern states as they will be heavily dependent on the location and intensity of storms. Many areas in the eastern half of NSW and central/southern Queensland should pick up more than 30mm of rain by Sunday night and some areas could see 50-100mm during this time. Severe thunderstorms are likely to affect multiple states during the next five days, so be sure to keep up to date with the latest warnings here: http://www.weatherzone.com.au/warnings.jsp