The Bureau paints a picture of no escaping the drier and warmer weather growers will be faced with across winter with the chance of El Niño conditions forming
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.
And for growers that have just completed a record planting everything could hinge on just when the El Niño will bite, and just how hard to complete a fourth near-record harvest in a row.
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,” Catherine Ganter outlined.
“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.”
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,” Catherine Ganter continued.
“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,” Catherine Ganter concluded.
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.
Catherine Ganter said even if an El Niño develops, its impact can vary depending on where you are, as well as from event to event.
Changes during El Niño could include:
- Reduced rainfall for eastern Australia.
- Warmer daytime temperatures for the southern two-thirds 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.
El Niño alert activated
The ENSO outlook has been shifted to El Niño ALERT. This means that while the El Niño–Southern Oscillation (ENSO) is currently neutral, there is approximately a 70% chance of El Niño forming in 2023. This is roughly three times the normal chance of an El Niño. An El Niño ALERT is not a guarantee that El Niño will occur, it is an indication that most of the typical precursors of an event are in place.
Oceanic ENSO indicators have warmed to El Niño thresholds. Models are forecasting that further warming is likely, with ocean temperatures expected to persist above El Niño thresholds in the central and eastern Pacific until at least the end of spring. The Southern Oscillation Index (SOI) has recently reached El Niño thresholds, with the 60-day SOI value at −10.6. Trade winds are currently close to average and cloudy conditions persist near the dateline.
The broadscale atmospheric pressure patterns are not typical of an El Niño. These current conditions indicate the Pacific Ocean and atmosphere are not yet reinforcing each other, as is the case during El Niño events.
