A series of brief violent storms yesterday afternoon and overnight led to pockets of heavy rainfall around the state, with one area receiving a one-in-20 year downpour. The Bureau of Meteorlogy has issued a storm warning, expected to include severe thunderstorms with very heavy rainfall and flash flooding, for the Illawarra, Central Tablelands and Central West Slopes districts. The storms are moving from west to east and there is a possibility of further severe storms in Sydney this afternoon and tonight, bureau meteorologist Chris Webb said. -------------- Do you know more? Message 0424 SMS SMH (+61 424 767 764) or email us with information. -------------- Cringila, in the Illawarra, received 44 millimetres of rain in 30 minutes, a once-in-20-year event, Mr Webb said. Oakdale, in Sydney's south-west, received 35 millimetres in 30 minutes and Bilpin, in the Blue Mountains, received 70 millimetres in 90 minutes, he said. There was also heavy rainfall in Strathfield where 17 millimetres of rain fell in just 15 minutes. The State Emergency Service was kept busy in the Illawarra region with 100 requests overnight, spokesman David Webber said. In the south of Sydney there were 35 requests for assistance, he said. Most of the requests were about trees that had fallen down and water inundation caused by flash flooding, Mr Webber said. Commuters on the F3 freeway are having a frustrating morning with heavy delays southbound due to an earlier accident. The Roads and Traffic Authority is warning of extensive delays on the road.