BOM Radar Loop – Willis Island

  • Location: Willis Island (lat 16.288° S, long 149.965° E)
  • Type: DWSR 2502 (C-Band)
  • Availability (Typical): Radar Availability (Typical): 0000—0315, 0430—0915, 1030—1515, 1630—2115, 2230—2400 (EST)

Interpretation Notes

Geographical Situation

Willis Island is a small island located in the Coral Sea approximately 450 km east of Cairns.The total land area is 7.7 hectares and the island’s highest point is 9 m above sea level.Natural grass covers much of the land together with several coconut and casuarina trees that have been planted near the meteorological office buildings.The Willis Island radar is well located to observe rainfall from tropical cyclones which can approach the coast of Tropical North Queensland between November and April.

Meteorological Aspects

The radar view is unrestricted in all directions and heavy rain due to strong convection and thunderstorms may be detected up to a maximum range of approximately 300 km. However, light showers will only be detected at a reduced range of the order of 200 km.The radar beam may lose power when passing through heavy rainnear the radar and this can reduce the effective range of the radar and the intensity of the returned echoes.Willis Island can be affected by tropical depressions and tropical cyclones during the northern wet season and experiences prevailing southeasterly trade winds during the dry.Rain echoes from severe tropical cyclones will rotate about a clear central eye with the heaviest rainfall usually located near the eye.

Non-meteorological aspects

During times of strong winds, false echoes from the sea surface or sea clutter may be visible in any direction.This is most likely to occur during dry season months when surges in the southeasterly trade winds are common.Sea clutter may be distinguished from rain echoes because it does not move with the background winds.