The anatomy of a cyclone
Cyclone season is from November to April with the peak month typically February
IF CYCLONE Debbie taught us anything this year, it’s that everyone is vulnerable to the wrath of Mother Nature.
You don’t have to live in north Queensland to be in the firing line for a cyclone and the fury that is unleashed as a ripple effect.
Here are a few things you need to know about cyclones heading into storm season.
WHAT IS IT?
A tropical cyclone is an organised, intense low-pressure weather system that creates strong winds and heavy rain as it sucks up moist, warm air vapours that are pushed outwards in thick cloud bands as the system spins. They get their energy from the warm tropical oceans but do not form unless the sea surface temperature is above 26.5C. Once formed, though, they can persist over lower sea-surface temperatures and may follow an erratic path. Become familiar with all five categories in the factbox on the right.
WHEN DO THEY COME TO TOWN?
Cyclone season is November to April with the peak month typically February. Even if the cyclone is off the north or central Queensland coast, it can cause heavy rainfall in the south of the state.
EYE OF THE TIGER
The eye of a cyclone can last a few minutes or a few hours and can vary in size from 10-100km. During this time, the wind dies down, there are no clouds or rain and even sunshine. But don’t be tricked – the cyclone has not passed by, so don’t go outside.
WHAT IS A STORM SURGE?
A storm surge – also called a storm tide – is a raised dome of seawater typically 60-80km across and 2-5m above the normal sea level, caused by a cyclone as it reaches the coast. The huge winds whip up the sea and push the dome of water over low-lying coastal areas. A storm surge comes in like a rapidly rising tide and can be extremely destructive. The waves and seawater can move inland quite quickly, damaging buildings and cutting off escape routes. If the surge coincides with a high tide, flooding can be extensive.
WATCH OR WARNING
The weather bureau issues a cyclone watch when cyclonic winds are expected within 24 to 48 hours. A warning is issued when cyclonic winds are expected within 24 hours.