Frequently Asked Questions (FAQ)

Climatology | Impacts | Extremes| TCs affecting WA towns | Forecast Accuracy
Frequently Asked Questions | Annual summaries

Definitions | Characteristics and Formation | Climatology | Extremes | Forecasting | More Information

Characteristics and Formation

7. What happens to cyclones as they move further south, say down the west coast?

Cyclones off northwest Australia typically develop between 5 and 15°S and reach maximum intensity between 10 and 20°S. As they move further south they will weaken over land or, for those remaining over water, weaken as they encounter an unfavourable environment (strengthening wind shear) and move over cooler water. They usually increase in speed as the steering winds in the mid-levels of the atmosphere increase and move to the south or southeast.

Occasionally a cyclone moves south and interacts with a mid-latitude trough and undergoes extra-tropical transition changing from a warm-cored tropical low to a cold-cored mid-latitude low. The structure, distribution of winds and rainfall changes significantly. For more information see Tropical Cyclones affecting Perth.