South Pacific Ocean Tropical Cyclone Intensity Scale - Australia and Fiji

Australia and Fiji

Any tropical cyclone that forms to the east of 90°E in the Southern Hemisphere is monitored by either the Australian Bureau of Meteorology and/or the Regional Specialized Meteorological Center in Nadi, Fiji. Both warning centres use the Australian tropical cyclone intensity scale, which measures tropical cyclones using a six category system. It is based on estimated maximum wind gusts, which are a further 30-40% stronger than the 10-minute average sustained winds. This is different from the Saffir-Simpson Hurricane Scale, which uses 1-minute maximum sustained winds.

When a tropical cyclone that has wind speeds below 35 knots (65 km/h, 40 mph) forms east of 160°E it is labelled as either a tropical disturbance or a tropical depression by RSMC Nadi. If it forms to the west of 160°E it is labelled as a tropical low by the Australian Bureau of Meteorology. However if it forms to the north of 10°S and between 90°E to 125°E the low is labelled as a tropical depression by the Tropical Cyclone Warning Center in Jakarta, Indonesia.

If a tropical depression should reach 35 knots (65 km/h, 40 mph), it will be named by the TCWC or RSMC and be classified as a tropical cyclone. Should the cyclone intensify further reaching maximum sustained winds of 65 knots (145 km/h, 75 mph) then the cyclone will be designated as a category three severe tropical cyclone. A severe tropical cyclone will be classified as a category five severe tropical cyclone should the cyclone's maximum sustained wind speed be greater than 110 knots (200 km/h, 130 mph) and gusts be above 150 knots (280 km/h, 175 mph).