The cyclone strength winds currently battering the NSW coast are being caused by an intense low-pressure system known as an East Coast Low. The stormy weather system,  formed in the Tasman Sea, hasn't hit NSW this strong since 2007 and is expected to be one of the longest lasting ever. East Coast Lows are particularly common in June and tend to be more frequent in autumn and winter. They are characterised by gales or storm force winds that can damage buildings, fell trees and powerlines, cause powerful surf that can damage the coast and, in some cases, run ships aground. They can also dump hundreds of millimetres of rain, causing flash flooding and riverine flooding. Climate specialist Don White from WeatherWatch told Daily Mail Australia: 'It forms occasionally, usually once a year. But this particular one is quite strong and close to the coast winds are up to 135kmh and rain up to 200mm.’ ‘This one is probably the strongest since 2007 and it is also going to be the longest lasting one,’ Mr White said. Scroll down for video . A large gum tree (left) that has been uprooted on a property at Booragul, a suburb near Lake Macquarie north of Sydney in NSW. Powerful winds on Monday night and Tuesday morning also brought down scaffolding (right) in Edgecliff, in Sydney's eastern suburbs . ‘They normally move away after 12 hours but this one is going to stick around for 24- 36 hours, which is unusually long for an East Coast Low.’ East Coast Lows draw strong, moisture-laden winds across the coast, which cause heavy rain to fall when they are uplifted by the hills and ranges that run parallel to the coast. On Monday night 24 Sydney suburbs incurred 100mm of rainfall, with Blacktown hit hardest, thanks to the latest East Coast Low. An estimated 100,000 homes are without power on Tuesday morning across Sydney, the Central Coast and Hunter region. And a floodwater rescue operation is underway in Hunter area where there have been wind gusts of up to 125km/h - levels recorded in category two cyclones. A radar loop (left) and a cloud map (right) show the East Coast Low weather system causing gales and storm force winds . Fire rescue in Narrabeen, in Sydney's northern suburbs, were called to a number of properties where storms had brought down trees . Ferry services have been cancelled at Parramatta (pictured) while services between Manly and Circular Quay have also been stopped . State Emergency Services Deputy Commissioner Steve Pearce told the ABC on Tuesday the police and NSW Fire and Rescue had been called in to help the SES on the 2400 call-outs they've received so far, with many more expected in daylight when people can see the damage around their homes. 'We've had 24 hours of relentless gale-force winds. I haven't seen this wind damage for years,' Mr Pearce said. Some have speculated this week’s East Coast Low will be the worst in five years, while meteorologist with Weatherzone Rob Sharpe told the Sydney Morning Herald: ‘This is going to be our most significant east coast low since spring.’ ‘The last major one that has affected Newcastle was in 2007. East Coast Lows were common in the 1970s but became less common in the 90s,’ Mr White said. Winds of at least 100km/h lashed parts of the east coast, causing this tree to fall on a car in East Gosford, on the NSW Central Coast, on Monday with a driver and passenger inside. They were treated for only minor injuries. They were treated for minor injuries by paramedics. The SES is preparing for damaging winds to hit parts of NSW over the next two days . A pedestrian is drenched while crossing  the street in the Sydney central business district during heavy rain on Monday . A ship makes its way out to sea in Sydney on Monday. The Bureau of Meteorology has been issued for Sydney Closed Waters, the Hunter Coast, Sydney Coast, Illawarra Coast, Batemans Coast and Eden Coast . The SES had responded to about 15 jobs on Monday morning, mainly in Sydney metro area . ‘If it is to the north of Newcastle the max effect occurs all the way down to Wollongong, which is in the vicinity of the nation where most people live so it causes the most damage.’ In June 2007 bulk carrier Pasha Bulker ran aground near Newcastle amid wind gusts up to 124km/h. Other notable east coast lows occurred in October 2004, when there were mean wave heights off Sydney of 5m with a maximum height of about 10m. In August 1998, more than 300mm of rain fell over four days in Sydney and Illawarra, 420mm at Beaumont and 401mm at Kangaroo Valley. In May 1974, 165km/h gust at the Newcastle Nobbies saw bulk carrier the Sygna run aground. And in August 1857, the Dunbar wrecked at South Head killing 121, with only one person surviving. A commuter wades through a flooded train station in Sydney's central business district on Tuesday morning amid wild weather . Winds as powerful as a category two cyclones have lashed the Hunter region of New South Wales, with the SES is receiving 200 calls an hour as wild weather continues to hit large parts of the state . TUESDAY . WEDNESDAY . THURSDAY . FRIDAY . SATURDAY . Pedestrians shelter under umbrellas from heavy rain in Sydney on Monday. Rain and damaging winds averaging 55 to 70 km/h with gusts to about 100 km are forecast to develop along the coastal fringe of the Sydney Metropolitan, Hunter and Illawarra regions . Snow has started to fall at Perisher in the Snowy Mountains of New South Wales . Perisher will see a snow shower or two on Monday with a maximum temperature of three degrees celcius . On Tuesday there will be a 30 per cent chance of a snow shower with temperatures expected to sit between -1 and 3 degrees . The first major snowfall of the year has happened at the ski fields at Thredbo, in southern New South Wales near the Victoria border . The area's forecast says to expect possible snow showers in areas above 1200m and temperatures between -2 and 3 degrees .
The weather system is called an East coast low. It is formed from low-pressure over the Tasman Sea.
They draw strong, moisture-laden winds across the coast, which cause heavy rain to fall.
They are particularly common in June and can dump hundreds of millimetres of rain.
They usually move away after 12 hours but this one is going to stick around for 24-36 hours.
East Coast Lows were common in the 1970s but became less common in the 90s.
'Close to the coast winds are up to 135kmh and rain up to 200mm,' weatherman Don White says.
Police and NSW Fire and Rescue have been called in to help the SES on 2800 weather related call-outs.