Extract from ABC News
The epicentre of this week's flooding rains was a stunningly beautiful valley south of Sydney called Brogers Creek.
Key points:
- Extreme rainfall totals have been recorded across New South Wales
- Flood records have been set on the Hawkesbury River and Wollombi Brook
- Queensland has seen its coldest pair of days in decades
The rain gauge there recorded 933 millimetres of rain in four days to 9am Tuesday — more than the average annual rainfall for Canberra, Melbourne, or Adelaide.
Photographer Damon Smith, who lives nearby, has described what it was like to be underneath the deluge.
But Mr Smith said, for him, the rainfall was normal.
"When the moisture-laden winds come roaring off the coast, and the moisture in the clouds gets pushed up the side of the hills, what happens? Boom, it all condenses."
Mr Smith believes Brogers Creek's unique micro-climate played a role in the huge rainfall total.
About 100 kilometres north, in Sydney, the rain totals were much less with only 208mm recording during the same period of time.
But the rain that did fall in the Warragamba Dam catchment west of the city was enough to drive peak spill rates over the dam on Sunday afternoon of 515 gigalitres a day.
Holiday plans disrupted
Downstream at Windsor, the Hawkesbury River peaked at 13.93 metres at about midday Tuesday — the biggest flood since March 1978, when the river reached 14.46m.
Just before the flooding rains arrived, dentist Rob Turnbull, who grew up at nearby Richmond, was fishing under Windsor Bridge with his two boys.
"It's hard to believe that the new Windsor Bridge can go under because it's so far above the river normally," he said.
With heavy rain forecast for Sydney and the Hawkesbury Nepean region, Dr Turnbull thought it a good idea to reschedule his holiday plans and get out of town before the rains came.
Instead, Dr Turnbull headed up the coast with the kids and their caravan to Tuncurry, near the mid-north coast town of Taree.
On Sunday, the Bureau of Meteorology (BOM) alerted residents of the mid-north coast that the storm that hit the Sydney region was re-forming to the north.
On Wednesday morning, Taree residents woke up after a night of torrential rain to discover the town had suffered its wettest night, with records going back to 1881.
In the 24 hours, up to 9am Wednesday, 305mm of rain fell at Taree airport.
Taree airport's rain records only go back to 1997, but before that, the nearby Patanga Cl weather station had never measured over 300mm in a day, in records back to 1881.
Camping nearby in their caravan was Dr Turnbull and his boys.
"At about 10:30 the police knocked on our door," he said.
The police told them that the SES had issued an evacuation warning and Tuncurry Bowling Club had been set up as the nominated evacuation centre.
"They asked can we leave the van and just go there for the peak of the flood because the park was at risk of inundation," Dr Turnbull said.
Records broken in the Hunter
Rivers were rising across the region, and to the south in the Hunter, inland from Newcastle.
Looking on was Daniel Williams, a flood risk management specialist for the Hunter region.
He watched Wollombi Brook at Bulga near Singleton reach 9.11m on Wednesday afternoon.
"It was the largest flood at Bulga in recorded history. So the previous largest was June 1949," Mr Williams said.
Nearby, Singleton recorded a major flood peak of 13.71m early on Thursday morning, which, while significant, was closer to a one-in-20-year event.
"It's 0.4m lower than the peak flood level at Singleton in June 2007, which is nothing like the largest on record at all," Mr Williams said.
Meanwhile, in Queensland…
While the NSW coast was inundated, temperatures were dropping in Queensland.
On Monday, Brisbane recorded a maximum of 14.4 degrees Celsius. The next day, Brisbane was even colder, reaching 14 degrees.
Together, the two days were Brisbane's coldest pair of days since 1956, according to forecasting provider Weather zone.
Climatologist associate professor Ailie Gallant from Monash University says, as strange as it seems, the rain in NSW and the cold in Queensland are connected.
"When these types of systems come through, they tend to cause extremes. And they can be quite different extremes across quite large areas," Dr Gallant said.
"So the unusual rain we've seen in the Northern Territory, the freezing cold temperatures in Brisbane, the flooding rains in Sydney are actually all connected to the same type of weather system.
"It just shows itself in different ways as it moves across the country."
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