After multiple years of flooding rains, people have had enough. But the Bureau of Meteorology’s severe weather outlook indicates we are going to have to keep picking ourselves back up again this season.
- The BOM’s severe weather outlook warns of increased risk of tropical cyclones, tropical lows and widespread flooding for eastern and northern Australia
- There is an elevated risk of grass fire in southern Australia
- Prolonged heatwaves are more likely in southern areas with higher humidity
The outlook warns of an increased risk of widespread flooding for eastern and northern Australia and an increased risk of an above-average number of tropical cyclones and tropical lows.
It finds normal bushfire potential in eastern states but an elevated risk of grass fire in southern Australia, and increased risk of prolonged heatwaves in southern areas, along with higher humidity.
There is a normal risk of severe thunderstorms but a possible increase in risk of thunderstorm asthma events if conditions are dry in late spring and early summer.
The combination of La Niña conditions in the Pacific Ocean and a negative Indian Ocean Dipole in the west means warm waters are fuelling these wet conditions from both sides and encouraging an early start to the northern wet season.
Now in the third La Niña year in a row — with rivers, dams and soil up and down the coast already brimming — it isn’t taking much to trigger floods, as we saw this weekend.
Most of the country is enjoying a brief respite from the relentless rain on Monday but water is still streaming its way down creeks and rivers, especially in New South Wales.
The next round of rain is expected from Tuesday night. More on the forecast below.
Judging from this outlook, it will be just one of many more rounds to come.
Heightened tropical cyclone risk
In hindsight, we have been lucky with cyclones over the past few years.
La Niña conditions usually encourage cyclones, especially along Australia’s east coast.
The average number of tropical cyclones forming in Australian waters is between nine and 11, with four crossing the coast.
This year, the BOM has said there is a 70 per cent chance of at least 11 cyclones, with an early start likely.
We usually associate cyclones with the tropics, but the south is not immune.
The warming climate is resulting in fewer tropical cyclones but those that do form are trending to be stronger and pushing further south.
The Gold Coast was hit by a cyclone in the 50s and Cyclone Seroja made landfall unusually far south on the west coast in 2021.
Ex-tropical cyclones should not be underestimated. Ex-Cyclone Wanda brought devastating flooding to Brisbane during the 1970s’ triple La Niña and many will remember the damage Ex-Cyclone Debbie caused in south-east Queensland in 2017, without underlying conditions being nearly as wet.
The outlook might be generally wet but that doesn’t mean we are off the hook for heatwaves.
Individual days are not likely to be as hot as in a normal or dry summer, but prolonged heat events, with high overnight temperatures and humidity, are likely.
That can make for dangerous conditions, despite lower maximum temperatures.
Heatwaves are Australia’s deadliest natural disaster, so please keep an ear out for the BOM’s new heatwave warning system being rolled out this year and check in with those around you who might struggle in the heat.
The silver lining of a thoroughly wet forecast has got to be a lower fire risk. But this is Australia. Fire can never be completely ruled out.
Vegetation growth caused by the abundant rain can dry out quickly.
“While long running large bushfires are less likely than during a drier season, such as 2019-20, continuing wet conditions during spring may further increase grass growth,” the BOM’s outlook states.
“This could increase fire danger during any period of hot and dry weather over summer.”
Grassy urban fringe areas should be especially aware of the grassfire risk.
The outlook warns those in coastal regions that unusually high tides are expected on January 23, 2023 for the New South Wales and southern Queensland coasts.
It gives the same warning for February 20 on northern Queensland coasts, including in the Torres Strait.
“Flooding is likely to occur in low-lying areas around these unusually high tides. More-severe coastal flooding could occur if coastal or offshore storms are also around at these times,” it states.
The outlook is suggesting a normal risk of thunderstorms this season, which means the usual barrage of storms for northern New South Wales and south-east Queensland.
It does warn of a heightened potential for thunderstorm asthma, especially if conditions are dry late in spring and for early summer, particularly in parts of Victoria.
ABC Emergency has a wealth of information on what you should do to get ready if the worst happens.
Forecast for the coming days
The current break in the weather is going to be over soon.
According to BOM forecaster Dean Narramore, the next system will move in to South Australia on Tuesday night.
“That’s going to produce widespread rain and thunderstorms on Wednesday and Thursday, through South Australia, western and southern New South Wales, and pretty much all of Victoria and Tasmania,” he said.
Heavy falls are possible on and north of the ranges in Victoria and for large parts of northern Tasmania.
“This rainfall on already saturated soils and catchments, as we’ve been saying for weeks now, is unfortunately going to lead to widespread flooding, possibly moderate to major flooding, particularly in northern parts of Victoria and possibly northern parts of Tasmania,” he said.
In good news, it looks as though the focus will be further south than last week and it should be just one system, rather than system after system.
The bad news, though, is that this system is slow moving.
“It’s a very slow moving system this one on Wednesday and Thursday. So we just kind of have this large and heavy band of rain just slowly moving across Victoria, southern New South Wales, eastern South Australia and Tasmania,” Mr Narramore said.
“This is going to be a prolonged-duration rain event where it’s just going to rain for many hours over large areas, leading to widespread flooding.”
On Friday, the system is expected to move into currently flooded regions in New South Wales.
“Thankfully, it will be a short burst and then it will all clear offshore as we get into Friday night, and particularly into the weekend it’s looking fairly dry across large parts of eastern and south-eastern Australia,” Mr Narramore said.
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