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Bureau of Meteorology issues La Nina Watch for South Australia

La Nina is typically associated with wet weather, meaning we could be in for a rainy winter. In the past, La Nina has been responsible for significant rainfall and flooding events around Australia.

The Bureau of Meteorology has announced a La Nina watch for later this year. This follows an extremely dry start to the year, with Adelaide recording one of its driest February to April periods in over a century, according to recent weather data. It comes as high atmospheric pressure continues to influence weather patterns in southern Australia, preventing the onset of typical autumnal rainfall.

La Nina, conversely, is typically associated with wet weather, meaning we could be in for a rainy winter. In the past, La Nina has been responsible for significant rainfall and flooding events around Australia.

Angus Heinz, a senior meteorologist at the Bureau, provided an update on the current climate conditions and what they mean for South Australia and the rest of the country.

“The Bureau has issued a La Nina watch,” Heinz stated. “This means there is an increased chance of La Nina forming later this year. It doesn’t mean that La Nina is underway or even that La Nina is guaranteed to form. Conditions in the tropical Pacific Ocean are currently neutral, although there are some signs that La Nina might form in the Pacific Ocean later in 2024.”

La Nina, along with El Nino, is part of a natural climate cycle known as the El Nino Southern Oscillation (ENSO). ENSO describes changes in the tropical Pacific Ocean that affect global weather patterns. These changes include shifts in sea surface temperatures in the central to eastern tropical Pacific Ocean and their connection with trade winds and atmospheric patterns. La Nina is the phase where the Pacific Ocean off Australia’s coast is cooler, while El Nino is the phase where the Pacific Ocean off Australia’s coast is warmer.

“La Nina historically can be wetter than usual for northern and eastern Australia during winter, spring, and into summer,” Heinz explained. “El Nino, on the other hand, historically can be drier than usual in eastern Australia during winter and spring and doesn’t have much impact during summer.”

When discussing the weather outlook, Heinz emphasised the importance of the Bureau’s long-range forecast. “When we’re talking about rainfall and temperature ahead, the best guide isn’t whether or not we’re looking at La Nina or El Nino. It’s actually the Bureau’s long-range forecast which can be found on the Bureau’s website. The long-range forecast is based on sophisticated computer modelling that looks at all the conditions in the ocean and the atmosphere. It’s the best guide for rainfall and temperature for the three months ahead.”

The long-range forecast for June to August indicates an increased chance of above-average rainfall for parts of Western Australia and South Australia. However, the forecast for eastern Australia, including Queensland, New South Wales, Victoria, and Tasmania, shows roughly equal chances of above or below median rainfall. Some eastern areas have no strong wet or dry signal, meaning the typical range of rainfall for this time of year may be the best guide for these areas.

Regarding temperatures, the long-range forecast for June to August shows that maximum and minimum temperatures are very likely to be above median across all states and territories.

Heinz also commented on the frequency of La Nina events. “In the Bureau’s history of ENSO events, La Nina has followed an El Nino in around 40% of events since 1900. Around 50% of years following an El Nino have been ENSO neutral, while around 10% of years, El Nino has redeveloped.”

While there is an increased chance of La Nina forming later this year, current conditions remain neutral. The best guide for the weather ahead is the Bureau’s long-range forecast, which indicates varied rainfall patterns and above-median temperatures across Australia from June to August. South Australians and other residents are encouraged to stay informed through the Bureau’s updates and forecasts.

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