As Tropical Cyclone Alfred barrels toward Australia’s eastern coast, residents from Brisbane to northern New South Wales are bracing for a storm event not seen in over half a century.
The cyclone, currently a Category 2 system, is expected to make landfall between Noosa and Coolangatta, north of Brisbane, late on Friday or early Saturday, bringing destructive winds, life-threatening flooding, and coastal erosion to some of Australia’s most densely populated areas.
According to the Bureau of Meteorology, Alfred could possibly reach a Category 3 status but the chances of that remain low. However, the storm was expected to remain on the stronger end of Category 2 when it makes landfall.
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That means winds of up to 150kmph per hour will be battering areas of Queensland and NSW, with rainfall totals expected up to 600mm, enough to swell up rivers and create flood risks in a wide, highly populated region.
Queensland premier David Crisafulli called Cyclone Alfred an “extremely rare event,” as he urged residents to pay heed to warnings.
The last time Brisbane saw a tropical storm reach this close to its shores, it was 1990. Gold coast acting mayor Donna Gates said in terms of destructive winds and heavy rain, the city hasn’t seen anything like this since 1952.
But it’s not just the size of the storm that is concerning experts – it’s how it has been moving.
Most cyclones that form in the Coral Sea follow a typical pattern: they track southeastward, away from the Australian coastline, as they get caught in mid-latitude westerly winds.
But Alfred has done the opposite. It initially moved out to sea southwards, travelling parallel to Australia’s east coast, and then took a sharp turn westward towards Australia’s eastern coast.
Dr Liz Ritchie-Tyo, a professor of atmospheric sciences at Monash University, explains that this shift is due to Alfred’s interaction with a mid-latitude trough – a system of low pressure that extended northward and altered the storm’s movement.
“When tropical cyclones interact with a mid-latitude trough, they undergo a process called extratropical transition,” she says. “During this process, they can re-intensify into a hybrid system, sometimes even stronger than the original tropical cyclone.”
Now, as the mid-latitude trough moves east, Alfred has been left under the influence of the subtropical ridge, which is pushing it westward – straight toward Australia’s southeast coast.
“This sharp westward turn is unusual,” she said.
