Heavy rain storm in west Australia raises cyclone threat

SYDNEY (Reuters) - A tropical low pressure system is bringing heavy rain and floods to northwest Australia, with a chance of up to 50 percent that it could strengthen into a tropical cyclone by Wednesday, weather forecasters say. Each year, cyclones close shipping lanes and disrupt mining of hundreds of millions of tonnes of iron ore, coal, sugar and other commodities in Australia. The low is moving slowly westwards and the risk of a cyclone is dependent on whether the low moves over open water for long enough, the Australian Bureau of Meteorology said. In the state of Western Australia, such storms, packing minimum sustained winds of 63 km per hour, frequently disrupt mining and loading at ports accounting for more than a fifth of the world's seaborne trade in iron ore. The likelihood of the system intensifying into a cyclone rises from 5 percent on Tuesday to between 20 percent and 50 percent on Wednesday, it said. However, the most likely track will keep the low over land or too close to the coast to enable a cyclone to develop, the bureau said. Last season 10 tropical storms reached cyclone strength on the east and west coasts, just under the national average of 11. The last time the number of cyclones exceeded the national average was in 2005/06, when 14 cyclones were recorded, nine rated as severe. The Australian cyclone season runs from Nov. 1 to April 30. (Reporting by James Regan; Editing by Clarence Fernandez)