Anatomy of Cyclone Yasi
Eye on Cairns: The latest weather bureau radar image shows cyclone Yasi as it heads towards and crosses the Far Northern coast. Natural events expert Prof Jon Nott says Yasi is strengthening over the warm waters of the Coral Sea.
AS cyclone Yasi pushed towards the state's Far North coast, The Cairns Post spoke to extreme natural events expert Prof Jon Nott, of James Cook University, to find out just what it all meant.
While he stressed he could not predict where cyclone Yasi would hit, the physical geography professor was able to explain the meaning behind the threat.
“A cyclone forms when a cluster of thunderstorms combine in the right wind conditions,” he said. “They don’t just combine, they form a new system that circulates in a clockwise direction.”
The process can be compared with a chimney sucking up energy at the base and spurting it out at the top.
With the wind circulating a small “defence” is created in the centre of the system, which develops into what is known as the eye.
Prof Nott said that during the passage of the cyclone centre or eye, there is a temporary lull in the wind that is soon replaced by destructive winds coming from the other direction. The eye is surrounded by the eye wall, marking the belt of strongest winds and heaviest rainfall.
He said the warm sea was the fuel for the cyclone and the waters off the Far Northern coast were the reason it was gathering pace as it approached.
“That’s its engine and that means when it hits land, it generally disappears,” he said.
“But the intensity and size of this one means that Yasi is predicted to maintain its force when it hits land.”
He said areas outside the Far North would still feel the effects of the cyclone.
And he said as it intensified – Yasi was upgraded to a category 4 cyclone last night – it would become more dangerous.
“The damage doesn’t increase incrementally, it increases geometrically,” he said.
A category 4 cyclone will bring 225-279km/h winds and the storm surge could see fast-running water inundate low-lying areas.
He advised all those in the firing line to remain calm and listen to emergency service workers’ instructions. “Do as you’re told and always follow what the emergency service workers are saying.”