Heatwave could have final say on Cyclone Jasper's track with northern tropical coast most likely target

heatwave could have final say on cyclone jasper's track with northern tropical coast most likely target

Cyclones are difficult to predict, but not all systems are created equal. (Bureau of Meteorology)

Cyclone Jasper’s future track is becoming clearer and the latest modelling data indicates the northern tropical coast is the most likely target.

Initial forecasts indicated the system may take a very unusual route to southern Queensland, or even north-east NSW, but the current severe heatwave over Australia’s interior will be the ultimate judge on where Tropical Cyclone Jasper makes landfall.

Essentially the longer the heatwave lingers the more likely Jasper will strike the far north Queensland coast, while a cool change for NSW early next week would have driven the system further south to central Queensland, or even stall the cyclone offshore.

So how does the air temperature over Australia influence the movement of a cyclone well off the east coast?

What controls a cyclone’s path?

You often hear cyclones are difficult to predict, but the truth is not all systems are created equal.

The movement of tropical low-pressure systems, like everything else floating in the atmosphere, is mostly dependent on the wind.

In the case of a cyclone, which generates its own wind, we are talking about the environmental flow outside the periphery of the system.

When the winds surrounding a tropical cyclone are strong, forecasting its movement is relatively straightforward – it will move quickly in a steady direction.

Severe Tropical Cyclone Yasi in 2011 is a classic example of a system which was easy to forecast and therefore had a slim cone of uncertainty.

Yasi was forecast more than 48 hours before landfall to strike the coast just south of Innisfail early on February 3 – exactly when and where landfall occurred.

Then you have the opposite situation when surrounding winds are light and variable, and forecasting becomes a nightmare – track maps for Kimi in 2021 just 36 hours prior to arrival showed a potential target for landfall more than 400 kilometres long and eventually the system petered out offshore without ever striking the coast.

Jasper being steered towards the north Queensland coast

Back to the current pattern — the link between the seemingly unrelated weather events of the heatwave and cyclone exists because the system responsible for soaring temperatures this week will also control Jasper’s course across the Coral Sea.

The intense heat is due to what’s called an upper high – a high pressure system a few kilometres above the ground.

An upper high causes air to descend towards the surface, and it warms rapidly on descent at a rate of up to 9.8 degrees Celsius per 1,000 metres.

Winds blow anticlockwise around highs (in the Southern Hemisphere) and the result is an easterly airstream above the Coral Sea and Queensland this week, steering Jasper towards the coast like a cork in a river.

Therefore, the longer the upper high and heatwave last, the longer Jasper will continue moving west towards Queensland’s north coast.

So what could disrupt this path? For Jasper to stall or turn left down the Queensland coast the centre of the upper high needs to move east of Australia early next week.

This would not only ease the current heatwave but also set-up a northerly flow to carry Jasper south.

The latest modelling indicates the southern track scenario is now extremely unlikely, meaning both an extension of the heatwave for western Queensland and NSW well into next week along with a cyclonic impact on the north Queensland coast.

Below is a non-official model generated strike probability for next Wednesday which shows the most likely target has shifted north of Cairns.

It’s still too early to make precise forecasts on when and where landfall will take place, or at what strength, and it’s still possible Jasper will stall before reaching the mainland.

How unusual is a December Cyclone for Queensland?

December cyclones on the Queensland east coast are very unusual – there have been only three since 1970:

  • Category one Tasha in 2010.
  • Category two Joy in 1990
  • Category three Althea in 1971

What makes this system even more intriguing is the presence of El Niño, which normally leads to a late onset of the cyclone season, along with the recent reduction in cyclone numbers due to climate change.

News Related

OTHER NEWS

Disrupt Burrup protesters searched and phones seized

Disrupt Burrup Hub group say police have issued move-on notices prohibiting access to the WA site. A group of climate activists and filmmakers say their phones have been seized during ... Read more »

The generation driving a ‘megatrend’ of poor mental health in Australia

As individuals, we have unique experiences that affect our mental health and wellbeing, but what about the collective experiences that influence each generation? The mental health of Australians has been ... Read more »

Geraldton meatworks set to reopen after five years in bid to meet chilled meat demand from Asia, Middle East

Syed Ghazaly wants to see the Geraldton abattoir reopen early next year to process 1,000 sheep a day. (ABC Mid West Wheatbelt: Chris Lewis) The new owners of a mothballed ... Read more »

Blues seek ‘growth’ as pre-season begins; new Hawk aims to be AFL’s serial pest

Carlton coach Michael Voss says he and his players understand there are heightened expectations on them, but insists the Blues are ready to develop individually and in their game plan. ... Read more »

Bulldogs continue signing frenzy with swap deal

The Bulldogs’ off-season signing frenzy is set to continue with the club reportedly set to land Cronnor Tracey in a swap deal. The Sydney Morning Herald reports Tracey is expected ... Read more »

Customers to weigh in as Optus disruption comes under microscope

Consumers and impacted businesses are being urged to have their say on the Optus outage, with the federal government laying out the terms of reference for its review into the ... Read more »

Released detainee unable to be contacted by authorities

It has been revealed a released immigration detainee is unable to be contacted by authorities. Border Force has referred the matter to the Federal Police as authorities are attempting to ... Read more »
Top List in the World