Tyler Redway
WINTER weather is predicted to be unusually warmer than average, not only for Mount Gambier but for the whole of Australia.
Bureau of Meteorology climatologist Jonathan Pollock said the weather phases were currently entering a neutral period between La Niña and El Niño patterns.
“Out in the Pacific Ocean, there’s this natural cycle along the equator where we sometimes get warm sea surface temperatures close to Australia during La Niña and often we get a focus of convection closer to us so we can get above average rainfall,” Mr Pollock said.
“That’s what we have been expecting from the three previous winters, we have had back-to-back La Niñas but now it looks like things have changed out on the Pacific Ocean and we might be moving toward an El Niño phase.”
Mr Pollock said the last time a triple La Niña period occurred was in 1998 which lasted until 2001.
He said there wasn’t a complete explanation as to why this was occurring but it was a topic which was being focused on by researchers.
“It’s a bit unusual to have three back-to-back La Niñas, it’s only happened a couple of times in our records,” Mr Pollock said.
“It’s definitely an area of active research, a lot of scientists and researchers are asking the same question but it’s not something we have a written statement for.
“We can consider some scenarios depending on what happens with our big climate drivers.”
He added during an El Niño phase, the warmer waters pull out into a central position to draw cloudy conditions away from this end of the Pacific which gives Australia dryer conditions.
“We have switched to a neutral phase at the moment but we reckon there’s about a 50 per cent chance it might happen (El Niño),” he said.
“There’s a similar phenomenon happening in the Indian Ocean as well called a positive Indian Ocean dipole which is another big seasonal driver where often if we do have one can mean below average winter/spring rainfall for parts of Southern Australia around Victoria and even Mount Gambier.
“It’s the increased chance of either one or both of those things happening which is really giving us that dry outlook for parts of the country.”
Mr Pollock said recent research suggested there may also be an increase in the frequency of large El Niño and La Niña events.
“Research suggests El Niño may bring heavier rainfall over the central and eastern tropical Pacific Ocean under global warming, and La Niña rainfall may be heavier in the western Pacific and over the South Pacific Convergence Zone, but what these changes mean for Australia is unclear,” he said.
“What the future holds for El Niño, La Niña and their impacts are the subject of current research.”