WHAT IS A STORM SURGE?
A storm surge is a rise above the normal water level along a shore as a result of strong onshore winds and/or reduced atmospheric pressure.
It's often associated with a tropical cyclone that makes landfall. In non-tropical areas it can be formed by intense low-pressure systems.
HOW HIGH CAN THEY GET?
A storm surge is usually about two to five metres higher than the normal tide level.
Their height is determined by a number of factors: cyclone intensity, speed and the angle it crosses the coast; the shape of the sea floor; and topography.
Storm surges are most dangerous when they occur at the same time as a high tide. This is known as a `storm tide'. (A high tide is expected in north Queensland at 9am on Tuesday.)
When this happens, typically safe areas can be affected. Sea water flooding can extend along the coast for more than 100km and inland for several kilometres.
These conditions are usually made worse by large waves produced by strong winds.
Most casualties during tropical cyclones occur as the result of storm surges.
HOW BAD HAVE THEY BEEN?
- In 1970, the Bay of Bengal off India was hit by Bhola Cyclone and a severe storm surge that killed up to 500,000 people.
- In 2008, a storm surge caused by Cyclone Nargis in Myanmar led to the deaths of more than 138,000 people.
- In 2013, the Philippines was struck by Typhoon Haiyan, which resulted in severe flooding and killed more than 3600.
WHAT TO DO IN A STORM SURGE
First, find out if you live in a surge-prone area and if you do, have a pre-determined place to which to retreat in the event of a storm surge. (Queensland authorities will be advising affected residents)
Also find out where your nearest safe high ground is and the safest way to get there.
Have an evacuation plan that includes what medicines you might need to take with you, as well as important documents, and how to rescue pets.
In the event of evacuation, if you choose to leave of your own accord, make sure you let your neighbours know.
Always listen to Bureau of Meteorology weather warnings so you're aware if conditions worsen.
