In Northern Australia the “cyclone” season can extend from November to May each year.
The number and extent of cyclones per year varies, but in reality it is not the number of cyclones that occur, more so their intensity.
Tropical cyclones are intense low pressure systems forming over tropical oceans and exceed gale force winds of 63 km per hour surrounding the centre of the tropical cyclone.
In the Southern hemisphere the wind pattern is clockwise and in the Northern Hemisphere counter clockwise.
You may have heard that a cyclone can be deemed to be a Category 1 to a Category 5.
This relates to the strength of the cyclone with a Category 1 as the weakest and Category 5 as the strongest, noting that all cyclones have the potential to cause damage to persons and property.
Category 1: up to 125 km/hr Slight damage to trees and farmland
Category 2: 126 – 169 km/hr Significant damage, minor house damage, severe damage to signs/trees and heavy damage to crops
Category 3: 170-224 km/hr Structural damage to house roofs and most likely power failures
Category 4: 225 – 279 km/hr Significant structural and roof damage. Potential airborne debris and widespread disruption to public utilities.
Category 5: greater than 280 km/hr Very destructive, extremely dangerous and potential for total destruction of structures and significant damage to cars, aircraft and rolling stock.
A number of useful web sites are available to keep up to date with current Cyclone information.
The Bureau of Meteorology has detailed information on tropical cyclones which may influence Australian coastal towns or cities.
This information includes:
- Forecast track maps
- Tropical Cyclone information bulletins
- High seas warnings
- Tropical cyclone technical information bulletins
- Specific area Tropical Cyclone advice
Tropical Cyclone information is freely accessible as a public service.
The Joint Typhoon Warning Centre (JTWC) is a United States Government website intended for use by U.S Government agencies however the information on the site is considered to be public information unless specifically annotated and may be freely distributed and copied.
Current information is included for the following areas:
- Northwest Pacific/North Indian Ocean
- Central/Eastern Pacific Tropical region
- Southern Hemisphere
When a cyclone is active, date/time stamped (in Universal Time Z)warnings are issued with the following information available:
- Warning text
- Warning graphic
- Satellite imagery
- Satellite fix bulletin
The JTWC also issues Significant Tropical Weather advisories with text and satellite imagery