Originally published by AusSMC.

The Bureau of Meteorology has moved from El Niño WATCH to El Niño ALERT, meaning there is around a 70% chance of an El Niño developing this year. Bureau of Meteorology Senior Climatologist Catherine Ganter said climate models and indicators now meet the Bureau’s El Niño ALERT criteria.

Organisation/s: Bureau of Meteorology

Funder: Bureau of Meteorology

Media release

From: Bureau of Meteorology

The Bureau of Meteorology issues an El Niño ALERT

Issued: 3:00pm AEST Tuesday, 6 June 2023

The Bureau of Meteorology has moved from El Niño WATCH to El Niño ALERT, meaning that there is around a 70% chance of an El Niño developing this year.

Bureau of Meteorology Senior Climatologist Catherine Ganter said climate models and indicators now meet the Bureau’s El Niño ALERT criteria.

“While the models show it’s very likely the tropical Pacific Ocean temperatures will reach El Niño levels during winter, we have seen some movement in the atmosphere towards El Niño conditions,” Ms Ganter said.

“While our El Niño ALERT criteria have been met, these changes will need to strengthen and sustain themselves over a longer period for us to consider an El Niño event,” she said.

The Bureau’s criteria for the definition of El Niño ALERT have been developed as part of a staged system to alert Australians on the increased likelihood of El Niño.

El Niño describes changes in the tropical Pacific Ocean that affect global weather and it occurs on average every 3 to 5 years.

During El Niño, there is a higher chance of drier weather in eastern Australia and it’s more likely to be warmer than usual for the southern two-thirds of Australia.

“The Bureau’s long-range winter forecast is for drier and warmer conditions across almost all of Australia and the climate conditions in the Pacific Ocean are already factored into our forecasts,” Ms Ganter said.

“The long-range forecast for winter also shows an increased chance of below average rainfall for almost all of Australia and the move to El Niño ALERT does not change this forecast.

“The Bureau currently forecasts Australia’s rainfall and temperature up to 3 months ahead. We use a climate version of our weather model to make these long-range forecasts and this model uses information about ocean and land temperatures, wind patterns and more.

“This model already takes into account the likely conditions in the Pacific Ocean, but also conditions elsewhere across the globe, such as the tropical Indian Ocean and how they are also likely to influence Australian weather and climate,” Ms Ganter said.

El Niño is the warm phase of the El Niño–Southern Oscillation (ENSO), where the climate is often drier than usual in eastern Australia during winter and spring.

ENSO describes a naturally occurring cycle in the climate system, including the location of warmer or cooler than average sea surface temperatures in the central and eastern tropical Pacific Ocean, and its connection with the trade winds and patterns in the atmosphere.

Ms Ganter said even if an El Niño develops, its impact can vary depending on where you are, as well as from event to event.

In Australia, changes during El Niño could include:

  • Reduced rainfall for eastern Australia.
  • Warmer daytime temperatures for the southern two-third of Australia.
  • Increased risk of extreme heat.
  • Increased bushfire danger in south-eastern Australia.
  • Increased frost risk linked to clear skies at night.
  • Decreased alpine snow depths.
  • A later start to the northern wet season.
  • Reduced tropical cyclone numbers.

More information is available on the Bureau’s website: 
Climate long-range forecast: bom.gov.au/climate/ahead/ 
ENSO forecast: bom.gov.au/climate/enso/outlook 
Climate Driver Update: bom.gov.au/climate/enso/ 
More about El Niño and La Niña: www.bom.gov.au/climate/about/australian-climate-influences.shtml?bookmark=enso

Expert Reaction

These comments have been collated by the Science Media Centre to provide a variety of expert perspectives on this issue. Feel free to use these quotes in your stories. Views expressed are the personal opinions of the experts named. They do not represent the views of the SMC or any other organisation unless specifically stated.

Dr Jatin Kala is a Senior Lecturer in Atmospheric Science at Murdoch University

“ENSO has a limited influence on the climate of southwest WA as compared to the Eastern states of Australia. However, El Nino conditions can weaken the Leeuwin current, which may lead to lower than average winter/spring rainfall, however, there are many other factors that need to be taken into consideration, such as the Indian Ocean Dipole, the position of the sub-tropical ridge, the Southern Annular Mode, all of which have some influence on rainfall in Western Australia. “

Last updated: 09 Jun 2023 10:20am

Declared conflicts of interest:

None declared.

Ruby Lieber is a PhD Candidate at the ARC Centre of Excellence for Climate Extremes at the University of Melbourne

“The Bureau of Meteorology has declared an El Niño alert. This means that there is a much greater chance than usual of an El Niño forming in the coming months (roughly three times as likely). However, there is still no guarantee that one will form.

If the tropical Pacific continues to warm and there is a weakening of the easterly trade winds, an El Niño may be declared. While the tropical Pacific Ocean has warmed to El Niño thresholds, the atmosphere is not responding in the way typical of an El Niño. Every El Niño is different and so we cannot be certain as to what the weather and climate will do in response. El Niño generally promotes hotter and drier conditions in Australia and increases the risk of drought and bushfire.”

Last updated: 06 Jun 2023 5:31pm

Declared conflicts of interest:

None declared.

Dr Nandini Ramesh is a Senior Research Scientist in Natural Hazards from CSIRO’s Data 61 and the University of Sydney

The change from an El Niño Watch to an Alert indicates that forecasts are now confident that an El Niño is developing, as we have moved beyond the uncertain autumn period. Warm water temperatures have spread across the crucial eastern-central tropical Pacific region, but the muted response from the atmosphere at this stage makes it difficult to know how strong the El Niño event will be.

An El Niño event’s strength is measured based on how warm the temperatures are over the eastern and central equatorial Pacific – from South America in the east to almost the dateline in the west. But how strong the impacts are on Australia are not obvious from the strength of the event – some of the worst bushfire seasons in Australia have been during weak to moderate El Niño events (e.g., 2019-20) rather than strong ones (e.g., 2015-16). Other factors, like the Indian Ocean Dipole, play an important role, and are predicted to promote dry conditions over much of Australia. The Bureau of Meteorology’s outlook predicts that the coming season will be warmer and drier than usual over much of the continent.

Last updated: 06 Jun 2023 4:52pm

Declared conflicts of interest:

None declared.

Dr Tom Mortlock is a Senior Analyst at Aon and Adjunct Fellow at the UNSW Climate Change Research Centre

“The latest upgrade from El Niño watch to El Niño alert by the Bureau reflects the increasing international model consensus that El Niño will be upon us by the summer. We have now passed the infamous (northern hemisphere) spring predictability barrier which means we can now be much more confident in El Niño model forecasts.
We know from the historical record that bushfire events are more likely during periods of El Niño whereas floods and cyclones are less likely (but can still happen). The concern now is that – with the long absence of El Niño and back to back La Niñas – the landscape is preconditioned for bushfire with significant fuel growth occuring.
If the forecasts are correct, it would be the first time in eight years (since 2015/16) since an El Niño event was last experienced in Australia.”

Last updated: 06 Jun 2023 4:13pm

Declared conflicts of interest:

None declared.