What are the Australian tropical cyclone categories?

April 06, 2006 - 03:09 PM UTC

Like the Saffir-Simpson scale used in the United States, the Australian cyclone severity index rates storms on a scale from 1 (weakest) to 5 (strongest) based on the maximum sustained winds. However, the Australian scale is created for weaker storms. Below is a table from the Australian Bureau of Meteorology explaining their scale:

Category	Strongest Gust (km/h)	Average Maximum Wind (km/h)	Approximate Central Pressure (hPa)	Typical Effects
1	< 125	63 - 88	> 985	Negligible house damage. Damage to some crops, trees and caravans. Craft may drag moorings
2	125 - 169	89 - 117	985 - 970	Minor house damage. Significant damage to signs, trees and caravans. Heavy damage to some crops. Risk of power failure. Small craft may break moorings.
3	170 - 224	118 - 159	970 - 955	Some roof and structural damage. Some caravans destroyed. Power failures likely. (e.g. Winifred)
4	225 - 279	160 - 199	955 - 930	Significant roofing loss and structural damage. Many caravans destroyed and blown away. Dangerous airborne debris. Widespread power failures. (e.g. Tracy, Olivia)
5	> 279	> 200	< 930	Extremely dangerous with widespread destruction. (e.g. Vance)

Below is another table from the Australian Bureau of Meteorology comparing the US Saffir-Simpson scale to the Australian cyclone severity scale.

10-min av. wind speed (knots)	1-min av. wind speed (kn)	USA Category	Australian Category	Wind gusts (km/h)	Wind gusts (kn)
57	65	Category 1	Category 2	148	80
61	70			157	85
65	75			169	91
70	80			181	98
74	85	Category 2		193	104
78	90		Category 3	202	109
83	95			215	116
87	100	Category 3		226	122
91	105			235	127
96	110		Category 4	248	134
100	115	Category 4		259	140
105	120			272	147
109	125		Category 5	283	153
113	130			293	158
118	135			306	165
122	140	Category 5		317	171
126	145			326	176
131	150			339	183

Posted by Bryan Woods