Australia Weather News

A tropical low sitting off the Northern Territory coast is forecast to become a category two cyclone by Thursday, the Bureau of Meteorology (BOM) says.

The BOM issued its first forecast track map for the system on Tuesday morning, indicating the tropical low – currently sitting north of the Tiwi Islands – will continue to head in a north-east direction over the next 48 hours.

By 10pm on Thursday, the system is expected to become a category two cyclone and head south towards the NT coastline, north of west Arnhem Land.

BOM forecaster Jonathan How said the system had begun to develop circulation.

"Over the next few days, as shown in the track map, it will start to move towards the north-east over the sort of Timor-Arafura seas and gradually start to strengthen," he said.

"At this stage, we are expecting to become a tropical cyclone by Thursday morning ... it'll be the first of the season for Australia."

He said conditions were "pretty favourable" for further development, once it becomes a cyclone.

"Sea surface temperature is pretty warm, sitting around 30, 31 degrees, so pretty quickly, it ... is expected to strengthen into a category two system by Thursday night," Mr How said.

"Then it takes a bit of a southerly track as we head into Friday. Beyond Friday, this is where the range of scenarios does grow. 

"Into Friday, it is likely to turn towards the south, but exactly how far west or east it does go is  a little bit too early to say at this stage.

"But it is expected to sort of move in the south-west direction over the weekend, and that could bring it down towards Darwin."

If it does eventuate, the cyclone will be named Fina.

Mr How said based on current forecasts and modelling, the BOM was not expecting the system to develop into a category three cyclone.

"It is pretty close to the coast. We'd want it to be a little bit further away from the coast over very open waters to strengthen [further]," he said.

"There's not really any sort of big monsoon burst or pulse of tropical winds coming through to give it the extra bit of oomph to get [to category three strength].

"At this stage, category two is the forecast."

Once it moves closer to land, Mr How said the system could reduce in strength.

"As cyclones move over land or move near land, it can start to lose a bit of their power," he said.

"We're waiting to see just how sort of it does progress as we head towards the weekend.

"But the message from [the BOM], though, is that people in Darwin are probably pretty aware not to get too caught up with the category as it moves towards the city, 

"Regardless, it is still a tropical low or a tropical cyclone and still will bring heavy rain, damaging winds and possible storms."

The NT Emergency Service has urged Top End residents to prepare for the cyclone to hit by organising a cyclone kit and shelter plans.

Darwin has not experienced a cyclone since Cyclone Marcus crossed as a category two system in 2018.

It left almost 29,000 properties without power.

Soon after coming to power, the Country Liberal Party NT government scrapped Darwin’s underground power rollout.

The strongest cyclone to ever hit Darwin was Cyclone Tracy in December 1974, which devastated the city and killed 66 people.