Australia's competing weather systems

AUSTRALIA'S COMPETING WEATHER SYSTEMS:

* Emerging weather systems off Australia's west and east coasts are competing to affect summer weather patterns across the country.

* Off the east coast a large El Nino system is developing which could become the biggest on record. El Nino raises eastern Pacific Ocean temperatures, often resulting in reduced rainfall across eastern Australia during winter and spring.

* Off the west coast an Indian Ocean Dipole, sometimes known as the Indian Nino, is also developing which will result in higher ocean temperatures and bring higher rainfall across Western Australia and into South Australia.

* Forecasters say the prevailing system will largely determine Australia's weather outlook during the coming spring and summer.