King tides and wild winds create perfect storm
A RARE COMBINATION of a king tide and an east-coast low pressure system, which resulted in heavy rain and high winds, was the root cause of the damaging storms along the New South Wales coast this weekend.
“It’s just bad luck that the weather system over the weekend occurred with a king tide,” said Philip King, the Bureau of Meteorology’s extreme weather desk manager.
Philip added that the gale-force north-easterly winds left many north facing beaches exposed. “The tide, combined with the number of rivers flooding and water trying to escape out to sea, produced incredibly severe conditions,” he said.
The main street of Picton, NSW, 80km south-west of Sydney was underwater. (Source)
The damage to Sydney’s Northern Beaches was from a combination of weather conditions that had created a “perfect storm”, according to Mitchell Harley, an expert in coastal erosion at the University of NSW in Sydney.
“Large waves are not uncommon here but we had large waves coming from a direction that was particularly concerning,” Mitchell told SBS News today.
“Normally the waves come from a southerly direction, but for this they were coming from an east to north-easterly direction which meant a lot more waves were coming in to the normally protected southern ends of the beach which creates a lot of destruction,” he said.
“This was combined with a king tide – the largest tides of the year.”
A Northern Beaches man catches a fish from his apartment balcony. (Source)
A king tide is an everyday term for particularly high tides, which is a predictable and natural event. It occurs when the Earth, Sun and Moon are aligned at a certain point, resulting in the highest tide seen over the course of a year.
The impact of the storms in NSW caused the flooding of 21 river systems, 8000 calls for help and left 60,000 homes without power, said Philip.
“While the wind speed wasn’t record level, the combination with the king tide had a significant impact,” he said. “Some sections of the coast recorded waves up to 13 metres.”
Parts of waterfront homes that were once 20m from shore were washed away. Some suffered erosion of up to 15 metres into their back-gardens, with pools and sheds being claimed by the sea.
Not much of the NSW east coast was spared, as this radar image shared by Sydney Airport (where flights were delayed by up to two hours) shows. (Source: Sydney Airport / Instagram)
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