However, the complex system, which models have found difficult to predict, looks likely to move away from NSW faster than initially forecast, reducing the damage from wild weather, Ben Domensino, a meteorologist from Weatherzone, said.
“This system had the potential to be quite bad for Sydney,” he said. “We’re likely to be spared from the most intense impacts.”
The bureau forecast as much as six millimetres of rain on Monday, with the chance of a thunderstorm during the evening. Rainfall could be as much as 30 millimetres at Observatory Hill in Sydney on Tuesday, with similar totals for Newcastle and Wollongong.
The bureau has also issued a warning of hazardous surf from Byron down to the Victorian border on Tuesday.
Perhaps the most unusual event so far has been the amount of snow reaching the higher peaks of the NSW Alps – such as Thredbo and Perisher – from the east.
“There’s a big stream of moisture that focused off south-east NSW and far-eastern Victoria,” Mr Domensino said.
The Alps would typically get most of their snow from interactions between moisture from north-western Australia and cold air coming up from the Southern Ocean.
Snowfalls so far are about 35 centimetres, “easily the best snow we’ve seen” for NSW resorts this winter, he said.
Lower levels, though, will have collected rain rather than snow, creating slushy conditions for drivers, while the Victorian Alps have largely missed out.
The event has so far brought record July daily rainfall of 75.2 millimetres in the 24 hours to 9am on Monday for Montague Island, Mr Domensino said. Data goes back to 1956.
Other places with large totals include parts of the South Coast, which remain in drought. Bega and Merimbula both collected 56.4 millimetres in the same period, with further falls since.
The large pool of cold air that has helped drive the intensity of the current weather will also move across northern NSW on Monday, bringing the chance of snow flurries to the Northern and Central Tablelands, Mr Domensino said.
Given the less severe than expected impacts and the fact the system won’t linger long near the NSW coast, it’s unlikely it will be categorised as an east coast low, he said.
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Peter Hannam writes on environment issues for The Sydney Morning Herald and The Age.