A man has died after being struck by lightning in the Adelaide Hills as violent thunderstorms roll over the region, causing flash flooding.  Police have confirmed they were called to Mount Barker, in the Adelaide Hills, after the 39-year-old man was struck by lightning.  READ MORE: Man dies after being struck by lightning in Adelaide Hills  The storm rolls in over Adelaide's Seacliff. (Supplied, is Bec Boltje)  Paramedics are at the location, which is believed to be a college, but the man died at the scene.  Adelaide’s southern suburbs, the Adelaide Hills and parts of the Fleurieu Peninsula have taken the brunt of the wild weather this evening, which has included heavy rain, hail and even flash flooding.  More than 20,000 properties are reportedly without power and the State Emergency Service said it had taken 61 calls for assistance, mostly in Adelaide’s southern suburbs, since the storm hit this afternoon.  The Bureau of Meteorology recorded 35mm of rain fall in about 30 minutes, with 1-2cm hail reported in the southern parts of the city.  Flooded streets in Adelaide's CBD. (9NEWS)  A wind gust of 89km/h was detected at Adelaide airport.  Motorists have been filmed driving through waterlogged roads and the State Emergency Service has urged motorists to go slow and stay safe.  The Big Wedgie giant inflatable waterslide at the popular beachside suburb of Glenelg also broke its mooring in the heavy rain, forcing an evacuation of the site as the slide blew away in the high winds.  There were also fears the wild weather could affect Stage Four of the Tour Down Under.  The severe thunderstorm warning for the Adelaide region has since been cancelled, with thunderstorms no longer occurring in the Adelaide Metropolitan, Mount Lofty Ranges, Yorke Peninsula and Lower South East districts.  There have been no reports of any injuries.  A severe thunderstorm warning is now in place for much of NSW.  Do you have photo or video of the storm moving in? Send it to contact@9news.com.au but please stay safe.  In NSW, the Bureau of Meteorology issued severe storm warnings for Sydney, Gosford, Newcastle and Wollongong as well as Nowra, Orange, Goulburn, Dubbo, Tibooburra, Cobar and Bourke.  Heavy rain, thunder and damaging winds are predicted for those areas as the wild weather rolls in this evening. Already, Sydney has copped a major soaking across its western suburbs, CBD and inner west.  The BoM is predicting between 30 and 40mm of rain across the Sydney basin this evening, meaning commuters will have a wet trip home.  The prediction has prompted the NSW SES to urge residents to be ready.  Wild weather moves towards Sydney (left) and the dark clouds gathering over Adelaide.  The severe thunderstorm warning for the CBD has now been cancelled, but it remains in place for north and western parts of NSW.  It’s the second soaking in as many days for Sydney. Yesterday North Parramatta recorded 48mm of rain, as wild weather lashed the CBD and western suburbs.  Motorists have been warned to expect significant delays over the coming days with a high number of people expected on the roads and wet weather predicted to continue over the weekend.  The State Emergency Service is now on high alert and have advised people in the affected areas they should:  * Move your car under cover or away from trees.  * Secure or put away loose items around your house, yard and balcony.  * Keep clear of fallen power lines.  * Keep clear of creeks and storm drains.  * Don't walk, ride your bike or drive through flood water.  * If you are trapped by flash flooding, seek refuge in the highest available place and ring 000 if you need rescue.  * Unplug computers and appliances.  * Avoid using the phone during the storm.  * Stay indoors away from windows, and keep children and pets indoors as well.  * For emergency help in floods and storms, ring the SES (NSW and ACT) on 132 500.  Download the 9NEWS Alerts app for iPhone or Android to get push notifications when a major story breaks near your location.
Sydney is expected to be lashed by another storm cell this afternoon, with meteorologists advising commuters be prepared for heavy rain.