Widespread showers and thunderstorms developed across northern parts of New South Wales and southern parts of Queensland on Saturday afternoon, with storms in southern QLD persisting until early this morning. Some of these thunderstorms were severe, bringing heavy rainfall, flash flooding, damaging wind gusts and large hail. Warwick in QLD's Darling Downs copped the nastiest storm at around 3:30pm EST yesterday afternoon, as it was lashed by 111km/h winds, bringing down trees and causing power outages across the town. This was accompanied by small hail as well as very heavy rain totalling to 35mm, with 9mm of this falling in just 5 minutes. In NSW's Northern Tablelands Armidale Airport copped a soaking under a near-stationary storm, picking up 43mm, with 22mm of this falling in just half an hour. Squash ball size hail (approximately 4cm) and wind estimates of 90-100km/h were also reported from Ashford, with small hail also at Glen Innes. Thunderstorms also brought widespread rain of 5-15mm to places that haven't seen good rain in months. Some locations under intense storms picked up much more, with Miles in QLD picking up 83mm, its highest rain since March. Dunmore also picked up 113mm, its heaviest rain in 11 years of records. Lightning was frequent across both states, with 70,000 lightning strikes recorded over northern NSW and southern QLD combined across the past 24 hours. The cause of the widespread thunderstorms has been a low pressure trough that is currently sitting over inland parts of NSW and QLD. This trough is being fed by moist easterly winds leading to high moisture levels, partly responsible for the rainfall totals that have been seen. The other reason is that wind shear has been weak, meaning storms are slow moving. Thunderstorms with this trough are likely to fire up again today over similar areas, with heavy rain and flash flooding again likely. Damaging winds and hail are a bit less likely than on Saturday.