Australians on the east coast could be in for months of rainfall and potential flooding following two key announcements by the nation’s weather bureau.
The Australian Bureau of Meteorology issued a La Nina alert on Tuesday afternoon, saying the weather pattern is looking increasingly likely to reappear for its third consecutive year.
The bureau also declared last week that a negative Indian Ocean Dipole event was already under way, and would likely continue through to the end of September.
Experts say parts of the country could be facing months of wet weather as a consequence of the coinciding weather patterns, which last intersected amid the 2010 Queensland floods.
The conditions could prove to be disastrous for flood-stricken communities in northern New South Wales, in which catchments and soil are still sodden following the floods earlier this year.
Indian Ocean Dipole
The weather bureau confirmed on August 2 that a negative Indian Ocean Diopole (IOD) was under way.
An IOD is an irregular weather pattern that involved the oscillation of sea surface temperatures.
The negative pattern triggers warmer waters around Australia and higher-than-average precipitation, particularly in the central and eastern states.
An average of four IOD events occur every 30-year period, with each lasting about six months – this particular event is likely to conclude by the end of spring.
The weather phenomenon is now looking increasingly likely to be followed closely by La Nina, a low-pressure system, which also promises to bring plenty of rainfall.
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La Nina alert
The bureau issued an alert on Tuesday afternoon, switching from a La Nina ‘watch’ to an ‘alert’ status.
This means there is now a 70 per cent chance of La Nina being declared by the end of the year – making its third consecutive appearance.
As seen earlier this year in the NSW Northern Rivers floods, La Nina events increase the chances of above-average rainfall for northern and eastern Australia during spring and summer.
Combined with the negative IOD event, experts say the the results could be catastrophic.
The two weather events last coincided in 2010 – the year of the devastating Queensland floods.
A negative IOD also coincided with a La Nina event back in 1974, the year of the Brisbane floods.
The severe weather event claimed 16 lives, with flood waters in Brisbane reaching 5.45 metres, and 12.15 metres in Lismore (just two metres shy of the 2022 floods).
Australia has been battered by La Nina over the past 12 months, the low-pressure system sweeping over the east coast at the beginning of the year.
Lismore notably experienced an unbelievable lashing of rain in February, hit with a year’s worth of rainfall in a single 24-hour period.
Oceanographer and University of New South Wales Scientia Professor Matthew England told the ABC he expected the rains to be ‘‘higher than average’’ once more, thanks to a likely La Nina.
‘‘Whether they match the floods of this year or last is yet to be seen,’’ he said.
‘Primed for flooding’
Given the onslaught of heavy rains and flooding earlier this year, the news of an IOD and a likely La Nina event are most unwelcome.
Professor England said large parts of the country were ‘‘primed for flooding’’, with potential for ‘‘devastating’’ consequences.
‘‘The soil over some of these areas is not even dried up from the rains of the last couple of years. So, it is really primed for more flooding and that is a concern,’’ he said.
‘‘These triple events can be very impactful because you are not seeing the drying out of the soil and then more rain.’’
The weather bureau’s senior meteorologist Laura Boekel echoed Professor England’s sentiments, saying the soil in the east coast ‘‘remains quite moist’’.
“We have not seen any of the ground dry up across most of Queensland. The soil remains quite moist,” she said.
“We are still expecting to see a wetter-than-average end to winter as well as spring … That means that we’re gearing up for a season that could see increased flooding.’’
Queensland Premier Annastacia Palaszczuk played down the chances of disaster in a press conference on Monday.
Following a cabinet briefing with the weather bureau, she said the conditions ‘‘could be similar’’ to those experienced earlier this year.
“These conditions could be similar to the conditions that we saw over the summer this year,’’ she told press.
Ms Palaszczuk said the government would be working to ensure it was ‘‘well prepared’’ to tackle the wet season.
‘‘The next step the government will be taking is to talk to all of the mayors just to make sure we are very well prepared and to see how everybody is going with the implementations of the recommendations from the last flooding event,’’ she said.
“I don’t want Queenslanders to get alarmed, but what we do want to see is people to be prepared.’’
