The Bureau of Meteorology has issued a La Nina watch for the upcoming months, signaling a potential shift in weather patterns. This announcement follows a notably dry period from February to April in Adelaide, with one of the driest records in over a hundred years. The persistence of high atmospheric pressure in southern Australia has hindered the expected rainfall for the season.
Contrary to the current dry conditions, La Nina typically brings wet weather, suggesting the possibility of a rainy winter ahead. Historically, La Nina has been associated with significant rainfall and flooding events across Australia.
Angus Heinz, a senior meteorologist at the Bureau, provided insights into the current climate conditions and their implications for South Australia and the broader region.
“The Bureau has initiated a La Nina watch,” Heinz stated. “This indicates an increased likelihood of La Nina formation later this year. However, it’s important to note that La Nina isn’t yet established or guaranteed. While conditions in the tropical Pacific Ocean are presently neutral, there are indications that La Nina may develop later in 2024.”
La Nina and El Nino are part of the El Nino Southern Oscillation (ENSO), a natural climate cycle. ENSO involves changes in sea surface temperatures in the tropical Pacific Ocean and their impact on global weather patterns. La Nina is characterized by cooler ocean temperatures off Australia’s coast, while El Nino signifies warmer temperatures.
“La Nina historically brings above-average rainfall to northern and eastern Australia during winter, spring, and into summer,” Heinz explained. “Conversely, El Nino tends to result in drier conditions in eastern Australia during winter and spring, with minimal impact in summer.”
Heinz stressed the importance of the Bureau’s long-range forecast in predicting weather patterns. “When considering future rainfall and temperatures, our long-range forecast, available on the Bureau’s website, provides the most reliable guidance. It’s based on sophisticated computer modeling that considers various oceanic and atmospheric conditions, offering insights for the next three months.”
The long-range forecast for June to August suggests an increased likelihood of above-average rainfall for parts of Western Australia and South Australia. However, for eastern Australia, including Queensland, New South Wales, Victoria, and Tasmania, the forecast indicates roughly equal chances of above or below median rainfall. Some areas in the east show no clear wet or dry signals, suggesting reliance on typical rainfall patterns for guidance.
Regarding temperatures, the forecast predicts that maximum and minimum temperatures are highly likely to be above median across all states and territories from June to August.
Heinz also provided context on the frequency of La Nina events. “In the Bureau’s historical data on ENSO events, La Nina has followed an El Nino in approximately 40% of cases since 1900. Around 50% of years following an El Nino have been ENSO neutral, while in about 10% of cases, El Nino has redeveloped.”
While there’s an increased chance of La Nina forming later this year, current conditions remain neutral. The Bureau advises the public to stay informed through their updates and forecasts, particularly as weather patterns evolve.
