Cyclone planning and preparation
Introduction
Tropical Cyclones are extremely powerful storms that form above the ocean. Sometimes they reach land, bringing dangerously high winds, tornadoes and large amounts of rainfall that can quickly escalate to flooding in vulnerable areas. This damage can occur near to shore or much further inland due depending on geographical features of that land and the intensity of the hurricane.
Cyclones often go by other names. A hurricane is a strong tropical cyclone that occurs in the Atlantic Ocean or northeastern Pacific Ocean whereas a typhoon occurs in the northwestern Pacific Ocean. In the Indian Ocean and South Pacific, comparable storms are referred to as tropical cyclones[1]. Often and generally they are simply referred to as Cyclones.
Winds over 120 km/h (75 mph) are referred to as having 'hurricane force' speeds.
Cyclones are named. Since the early 1950s, hurricanes have been named after women. In 1980, male names were introduced, and now the storms are named alphabetically, alternating between male and female names. These names are repeated every six years unless the storm is particularly severe.
Cyclone strength categories
When a cyclone is announced, it is often referred as having a certain category of strength. It is useful to know what those categories mean relative to their impacts such that you can better prepare[2].
Category 1
- Damaging winds. Slight or no house damage. Damage to some crops, trees and caravans. Sea vessels may drag moorings.
- Maximum mean wind speed 63–88 km/h.
- Typical strongest gust is up to 125 km/h.
Category 2
- Destructive winds. Minor house damage. Significant damage to street signs, trees and caravans. Heavy damage to some crops. Risk of power failure. Small craft may break moorings.
- Maximum mean wind speed 89–117 km/h.
- Typical strongest gust 125–164 km/h.
Category 3
- Very destructive winds. Some roof and structural damage. Some caravans destroyed. Significant damage to crops and trees. Power failures likely.
- Maximum mean wind speed 118–159 km/h.
- Typical strongest gust 165–224 km/h.
Category 4
- Significant roofing loss and structural damage. Many caravans destroyed and blown away. Extensive damage to vegetation. Dangerous airborne debris. Widespread power failures.
- Maximum mean wind speed 160–199 km/h.
- Typical strongest gust 225–279 km/h.
Category 5
- Extremely dangerous with widespread destruction of buildings and vegetation.
- Maximum mean wind speed greater than 200 km/h.
- Typical strongest gust greater than 279 km/h.