Australian Bureau of Meteorology (BOM) Outlook for next three months - Part 1

 

There is weather and there is climate.

While we grumble about cold weather and rain this winter, global warming is still inexorably changing Australia's climate as the continent and the oceans around it grow warmer and seasonal rainfalls become more erratic.

La Niña only dissipated in early March 2023 and El Niño was present in the Northern Hemisphere by early June and may be across the Southern Hemisphere before September - the ocean around the Galapagos Islands just south of the Equator is already warming to 20 degrees. It is beginning to appear as if the near average weather pattern period between these two extremes in the global ENSO cycle is beginning to contract.

This is the long range forecast for the next three months for Australia.

Australian Bureau of Meteorology, Climate outlooks—weeks, months and seasons:

Long-range forecast overview

Issued: 15 June 2023

• For July to September, below median rainfall is likely to very likely (60% to greater than 80% chance) for much of the eastern two-thirds of Australia and south-west WA.

• July to September maximum temperatures are likely to very likely warmer than median (60% to greater than 80% chance) for almost all of Australia.

• Above median July to September minimum temperatures likely to very likely (60% to greater than 80% chance) for most of Australia.

• This forecast is influenced by a number of factors, including warming in the tropical Pacific Ocean beyond El Niño thresholds, the potential development of a positive Indian Ocean Dipole, and record warm oceans globally.

Currently Australia’s ENSO Outlook shows El Niño ALERT, which indicates a 70% chance of El Niño forming this year. This equates to roughly three times the normal chance of an El Niño forming.

Rainfall - Totals that have a 75% chance of occurring for July to September

Max temperature - The chance of above median max temperature for July to September

Australia: Sea Surface Temperature Anomaly Outlook – July to November 2023

U.S. NOAA Daily Global 5km Satellite Sea Surface Temperature, 17 July 2023

Click on images to enlarge

Climate Change State of Play in Australia 2022: it's later than you think

According to a Nature Communications article published on 15 November 2022; The El Niño-Southern Oscillation (ENSO) is the strongest and most consequential year-to-year climate fluctuation on the planet, with significant societal and environmental impacts that are felt worldwide. 

This is an Australian Bureau of Meteorology (BOM) video explaining how the El Niño-Southern Oscillation Index (ENSO) shapes Australia's weather.

As for current ENSO conditions. BOM states that La Niña retains its strength and continues in the tropical Pacific. Atmospheric and oceanic indicators of the El Niño–Southern Oscillation (ENSO) reflect a mature La Niña, including tropical Pacific sea surface temperatures, the Southern Oscillation Index (SOI), and tropical cloud patterns.

Its forecast for La Niña is that by December 2022 it will have weakened as ENSO begins a return to its neutral position. However, as the Southern Annular Mode (SAM) is positive and likely to continue to be positive into December, this increases the chance of above average rainfall for parts of eastern New South Wales, eastern Victoria, and south-eastern Queensland, and increases the chance of below average rainfall for western Tasmania. 

Climatologists have known for some time that the ENSO has developed greater strength since the 1950s in comparison to past centuries, supporting an emerging increase in ENSO variability under greenhouse warming.

New research is disclosing why it is that to our layman's eyes this system may become more erratic and harder to predict in its response to climate change-induced ocean warming that continues unabated.  

This research has found the influence of climate change on El Niño and La Niña events, in the form of ocean surface temperature changes in the eastern Pacific, will be detectable by 2030. This is four decades earlier than previously thought. 

What this indicates for Australia is more droughts, more floods and more intense cyclones over a wider area. 

That in all probability, all three tiers of government - and communities both large and small across the country -  have less than eight years to prepare for a worsening of the climatic extremes we have already begun to experience since the start of the new millennium.