Warm oceans, shifting winds: What is the science behind Cyclone Alfred’s strength?

For the first time in more than five decades, a tropical cyclone is on track to hit Australia’s relatively temperate east coast.

Slow-moving Cyclone Alfred is barrelling toward Brisbane - Australia’s third biggest city - and the nearby tourist town of Gold Coast. With it comes the threat of torrential rain, powerful winds and flooding to the border area between Queensland and New South Wales.

After briefly stalling Wednesday night, Alfred is now predicted to make landfall on Saturday, according to forecasts from the country’s Bureau of Meteorology (BOM). It is then forecast to batter Brisbane with rain and destructive winds for at least 12 hours.

While cyclones are common in Queensland’s tropical north, they are rare in its temperate border with New South Wales. The last time a cyclone struck the Gold Coast was in 1974, when Cyclone Zoe brought heavy flooding to the region. 

What’s behind this unusual storm?

Current forecasts maintain Alfred as a Category 2 cyclone. Meaning, it will have winds that can gust up to 164 kilometres per hour. But its strength could still intensify before it makes landfall, experts have cautioned.

The BOM has warned that Alfred could drop more than 800 millimetres of rain in some regions - more than the total annual average for March - raising concerns about flash flooding and river overflows. Strong winds and high tides could also exacerbate coastal erosion.

Authorities have issued several warnings as the storm intensifies offshore, urging residents in vulnerable areas to prepare for severe weather conditions.

In a public address on Wednesday, Queensland Premier David Crisafulli encouraged residents “to absorb the warnings from all manner of sources.”

On Thursday morning in Australia, Crisafulli