Cassowary Coast Regional Council

Storm Tide Storm Tide

What is a storm tide?

A storm tide is a rise above the normal water level, along a shore, that is the result of a tropical cyclone.

When a cyclone forms over open waters the strong winds pushing the water, combined with the low atmospheric pressure in the eye of the cyclone, cause the level of the sea to rise.

This results in the formation of large waves.

If this happens away from land, the water can escape and move freely away from the building storm. As the cyclone moves towards land and the depth of the water becomes shallower, the ever-increasing wall of water does not have a chance to flow away. These large waves may inundate land and cause destructive damage to anything in their path.

Please note that inundation by storm tide is not comparable with riverine flooding.

Storm tides will be accompanied by gale force winds, with successive waves of seawater rapidly moving across the foreshore. Trees, building material and other debris may be carried along by the storm tide.

Any evacuation must occur before the storm tide event.

A storm tide event should not be confused with a tsunami. A tsunami is a series of waves generated by a sudden upward movement of the ocean floor, normally due to earthquakes and is NOT related to a cyclonic event.

What if I am in an Evacuation Zone?

If your property is located in an evacuation zone, you need to read this information. It is important to understand what you need to do in the event of a storm tide.

Identify where your residence is located on the evacuation map and familiarise yourself with your evacuation zone and routes. 

If you are in a red, orange, yellow or blue zone, there is a chance that your property may be inundated in a storm tide event. The height of the predicted storm tide during the disaster event will determine which zones are affected.

If you are not located in a coloured zone, you are outside the storm tide inundation threat area.

How to read and the use the storm tide evacuation maps

  1. Identify where your residence is located on the map.
  2. If you are in one of the coloured zones, you may be at risk from storm tide inundation.
  3. Identify your evacuation route to your pre-determined safer location.
  4. During a cyclone event tune in to warnings. You can hear them on local radio stations i.e. ABC Far North and Radio 4KZ. Authorities will advise which zones need to evacuate.

Evacuation Zones

RED EVACUATION ZONE - INDICATES AREAS AT HIGHEST RISK OF FLOODING FROM CYCLONE STORM TIDE.
 
ORANGE EVACUATION ZONE - INDICATES AREAS AT HIGH RISK OF FLOODING FROM CYCLONE STORM TIDE.
 
YELLOW EVACUATION ZONE - INDICATES AREAS AT MODERATE RISK OF FLOODING FROM CYCLONE STORM TIDE.
 
BLUE EVACUATION ZONE - INDICATES AREAS AT LOW RISK OF FLOODING FROM CYCLONE STORM TIDE.
 

What do storm tide evacuation zones mean?

Residents in the Red Zone face the highest risk of inundation from a cyclone storm tide. The Red Zone includes low-lying coastal areas and populations at greater risk.

Residents in the Orange Zone face a high risk of inundation from a cyclone storm tide. The Orange Zone may experience storm tide inundation during moderate events.

Residents in the Yellow Zone face a moderate risk of inundation from a cyclone storm tide. The Yellow Zone may experience storm tide inundation during larger events.

Residents in the Blue Zone face a low risk of inundation from a cyclone storm tide. The Blue Zone may experience storm tide inundation during the most significant events.