The seed is the current MTSAT water vapour animation. Cyclone Yasi is 2-3 times the size of Katrina with 2 days before landfall.
Yasi is about the size of the entire state of Queensland, which is 3 times larger than the American state of California. Seawater temperatures along the coast exceed 32C/90F with peak wave heights already above 16 metres/50 feet.
Queensland chief forecaster Jim Davidson predicts Yasi will be Cat 4 at landfall, possibly Cat 5. He expects it to dump more than 1 meter/3 feet of rain over thousands of square miles of recently flooded land. Because of the size of this cyclone it will take at least a couple of days to dissipate, and is expected to reach the central Australian town of Alice Springs by Sunday.
Landfall is certain due to the presence of a monsoonal trough with very low wind shear. Queensland Premier Anna Bligh has warned this is one of the largest cyclones ever to hit Queensland.