More than 300mm of rain has fallen in parts of eastern NSW during the last two days, resulting in flash flooding. A low pressure trough moving slowly along the NSW coast brought persistent rain and storms to parts of the Hunter and lower Mid North Coast during the last 36 hours. The heaviest falls so far have occurred on the Barrington Tops, where a rain gauge at Careys Peak received 339mm during the 48 hours to 9am today. This was the site's heaviest rain in at least nine years. Nearby, Dungog picked up 287mm during the last 48 hours and Upper Chichester's 233mm in this time fell almost entirely within six hours on Wednesday morning. Forster's 174mm during the 24 hours to 9am today was it's heaviest rain in 15 years. Williamtown received 122mm during the 24 hours to 9am on Thursday, which is 1mm short of its entire March average and the heaviest daily rain in two years. Tocal (124mm), Cessnock (66mm) and Nobbys Head (74mm) also had their heaviest rain since 2016 during the last 24 hours. For Tocal and Cessnock, this was their heaviest daily rain during March in 41 years and at least 22 years, respectively. Rain and storms will remain heavy over parts of the Mid North Coast and Northern Tablelands Districts today and on Friday, with a severe weather warning in place for flash flooding. Minor river flooding is also occurring in parts of the Lower Hunter today. Fortunately, major flooding is unlikely to develop in the Hunter, despite this deluge. A lengthy spell of dry weather in recent months left river catchments dry before this week's heavy rain started falling. Visit http://www.weatherzone.com.au/warnings.jsp for the latest severe weather and flood advisories.