Wet weather will likely continue as La Nina starts to run out of steam
Australians with forecast fatigue after three years of floods might feel the urge to do a weather dance after BOM’s October update suggests this weather cycle will finally come to an end
READING LEVEL: GREEN
The damaging weather system that has brought three years of floods, record-breaking rain and cooler temperatures across Australia could end within months.
The Bureau* of Meteorology’s* (BOM) October climate modelling* suggests La Nina will end in early 2023, bringing relief to hundreds of flood-impacted communities.
A La Nina system typically increases the chance of above-average rain for northern and eastern Australia during spring and summer. The current La Nina has led to major downpours in the eastern states this year.
And major water volumes are now flowing into South Australian rivers, causing flooding in the Mid-North and Riverland.
A typical La Nina period would be expected to end over summer or in early autumn, but as this is the third La Nina in a row, it could be relatively short, leading meteorologists to believe it might end by January or February.
“We are still expecting to see increased rainfall and flooding risk into summer, but heading into early 2023, this La Nina looks like being over,” said the bureau’s senior meteorologist Jonathan How.
“Heading into this La Nina, we were very confident it would be a shorter one compared to the two previous ones, which dragged on,” he said. “(October’s) update really confirmed that. Some models say December but others say neutral* conditions (will return) in February.”
But Mr How said it was likely the stormy, flood-inducing* weather would continue for some time to come.
“Widespread* flooding beyond what we have already seen is a possibility,” he said.
The SA Department of Environment and Water forecasts the River Murray flow at the SA border will reach 120GL* a day in early December.
There is a “medium probability*” it will reach 140GL a day and “low probability” that flows could reach 160GL.
The flow will be the highest since 1974, when it was 180GL a day at the SA border.
The 1956 flood, which was the largest recorded, peaked at 341GL a day at its worst.
The La Nina and El Nino weather events are at opposite ends of the scale, with a neutral middle being normal weather conditions.
La Nina and El Nino occur when the Pacific Ocean and surrounding atmosphere changes from its normal state. In an El Nino event, the central and eastern tropical Pacific warms up, and La Nina does the opposite, bringing cooler conditions.
GLOSSARY
- bureau: department of government that does a particular job
- meteorology: science of the atmosphere and its phenomena, including weather forecasting
- modelling: programming based on global patterns in the ocean and atmosphere, and records of weather that occurred under similar patterns in the past, to predict future weather
- neutral: without significant qualities of its own, having limited impact on other things
- inducing: causing something to happen
- widespread: existing or happening in many places or among many people
- GL: gigalitre, 1000 megalitres or 1000,000,000 litres
- probability: a branch of maths that looks at how likely something is to happen
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QUICK QUIZ
- When is La Nina predicted to end?
- How many La Nina weather systems has Australia had in a row?
- River Murray flow at the SA border is forecast to reach what level?
- The flow will be the highest since what year?
- What year was the largest SA border flood and what was the peak?
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CLASSROOM ACTIVITIES
1. Flood risk
A senior meteorologist states in the article that widespread flooding in the months to come is still a possibility. How do you think communities that are currently flooded, or have commenced cleaning up from floods, could prepare for further flooding in the coming months? Give some suggestions below:
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What could local councils and governments do to help communities prepare for this possibility?
Time: allow 25 minutes to complete this activity
Curriculum Links: English; HASS; Personal and Social; Critical and Creative Thinking
2. Extension
Why do you think this La Nina event is expected to be shorter due to the fact that it’s the third La Nina in a row? Explain your answer.
Time: allow 15 minutes to complete this activity
Curriculum Links: English; Science; Critical and Creative Thinking
VCOP ACTIVITY
1. News: condensed
Identify the most important pieces of information in this article and write a condensed version of it using 50 words or less.
Draw a picture or diagram to support your condensed news story.
Time: allow 25 minutes to complete this activity
Curriculum Links: English; Science
2. Extension
Compare your condensed news story with a classmate. Did you both include the same information or are your stories quite different? Discuss your choices and then work together to create a final condensed version of the story that you both agree tells the important parts that a reader would need or want to know.
Time: allow 20 minutes to complete this activity
Curriculum Links: English