The impending cyclone season – which begins in November and runs until April – typically brings between 10 and 13 cyclones to Australian waters, with around four of those usually traversing the coastline.
A tropical cyclone is a low-pressure system that develops over warm waters, when the sea-surface temperature is above 26.5 degrees celsius.
It can reach wind speeds of over 63 km/hr. Severe gusts have hit 280km/hr at the core, known as the ‘circular eye’.
Tropical cyclones can last for several days and cause heavy rain, floods, and strong winds.
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'Dangerous' flooding
Cyclones are categorised from one to five - category one being the least severe with minimal house damage, while category five means extremely dangerous with widespread destruction.
According to senior climatologist Dr Paul Gregory, the effects of offshore tropical cyclones can be felt on coastal regions from rough seas and storm surges.
“While the tropical cyclone outlook points to a typical season, as we saw earlier this year with severe tropical cyclone Debbie, one event can have a devastating effect on a number of communities,” he said.
“It is rare that cyclones are evenly spread across the season. Last season saw only one tropical cyclone form before mid-February, which was a very late start. But then eight subsequent cyclones in the region brought the season's total to nine.
“When tropical cyclone Blanche crossed the West Australian coast on 6 March, it was the latest date that the first cyclone had crossed the coast on record. Tropical lows also form during the severe weather season.
“While these may lack the damaging winds and storm surges of cyclones, they can still cause widespread and very intense rainfall and dangerous flooding.”
The likelihood of impact
The Bureau of Meteorology has outlined the likelihood of tropical cyclones striking Australian regions during the season. It says:
- Western Australia is likely to have around two coastal impacts, with the "significant risk" of at least one severe tropical cyclone coastal impact.
- The north has a 53 per cent chance of an "above average" number of tropical cyclones (there are usually around three) with at least one coastal crossing expected.
- An average season is expected in the east – where around a quarter of tropical cyclones usually cross the coast.
- And in southern Australia, around four tropical cyclones usually make landfall.
How to prepare for a cyclone
Tropical cyclone forecasts and warnings are issued on the Bureau of Meteorology's website and via its Twitter page.
It also has a safety checklist to ensure the public is prepared in the event of a cyclone. Among the guidelines are to ensure any loose items inside or outside your home are secure; have an emergency kit to hand, including a portable battery radio and food, and an evacuation kit, with warm clothes, any medication and valuables; and follow state emergency services' advice.
