Some of the worst thunderstorms of the season are set to lash parts of NSW and QLD, with a focus on the slopes and plains. This afternoon a low pressure trough is producing a line of storms stretching through Broken Hill, Echuca and Port Albert. A low and upper trough is also producing showers and storms over eastern parts of South Australia. This two systems are both tracking further east today and will combine with ferocious intensity tomorrow. On Monday, the worst storms will be spread across the North West and Central West Slopes and Plains districts in NSW. Storms in these districts are likely to see large hail and have a significant risk of producing damaging wind gusts above 90km/h and giant hail greater than 5cm in diameter. The most at risk area is near a line from Parkes to Moree. Over the following days the most dangerous storm area will shift further north and become marginally less dangerous. On Tuesday they should be in the NW Slopes and Plains and in Queensland's Darling Downs and Granite Belt. On Wednesday they will stretch from Mungindi to Biloela and on Thursday in Queensland's central east. It is very important to prepare for these thunderstorms as they have the potential to produce some significant damage to localised areas.