By Colin Packham
SYDNEY (Reuters) - Australia's weather bureau said on Tuesday that climate indicators show an increased chance of an El Nino weather pattern, often linked to heavy rainfall and droughts, returning later this year.
The data predicted an El Nino could return sometime between mid-winter and spring this year in the southern hemisphere, Australia's Bureau of Meteorology said in a statement.
El Nino, also called "Little Boy" or "Christ Child", is a warming of ocean surface temperatures in the eastern and central Pacific.
The pattern typically brings below average rainfall for the Asia Pacific region, threatening the yields of agricultural crops, while America is often hit by wetter than average weather.
"Eastern and central tropical Pacific Ocean temperatures have continued to warm over the past fortnight, while trade winds have remained weaker than normal," the weather bureau said.
"Likewise, the Southern Oscillation Index has become more strongly negative over the past month."
The index, which is calculated using the pressure differences between Tahiti and Darwin, gives an indication of the development and intensity of El Nino events in the Pacific Ocean.
Sea surface temperatures in the far eastern equatorial Pacific were more than 1 degree Celsius warmer than usual in June, the weather bureau said.
(Editing by Ed Davies)