Thunderstorms firing up through southwest WA are expected to enhance Perth's already sodden summer. Storms are pushing south into southwest WA along a trough of low pressure, which is drawing heat and moisture into the region from the tropics. Rain from this system has so far remained north of Perth, although showers are expected to develop in the city during the day. Round Hill in the Central West district recorded 58mm of rain, most of which fell in just one hour. Dalwallinu managed to record 29mm of rain last night, their heaviest since February last year. As the trough deepens over Perth today, thunderstorms are likely to develop. These storms could potentially become severe due to the risk of flash flooding from heavy rain and damaging winds. The story will be much the same tomorrow for the WA capital, with another round of potentially severe thunderstorms likely to develop in the afternoon.