As Trevor and Veronica loom over the northern Australian coast they are stirring up a storm of questions which have been hurled at the weather desk.

Shouldn't the season be over by now? What happened to a below average? Two at once, is that unusual?

So I called on Sarah Scully, from the Bureau of Meteorology's extreme weather desk to get you some answers.

Wait, isn't it autumn?

Yes, summer may be over, but the cyclone season most certainly isn't.

"Typically the tropical cyclone season is between November and April, peaking in February and March. At the moment we're in mid to late March, so it's fairly typical," Ms Scully said.

The season thus far has been pretty close to normal too.

"So far there have been eight cyclones in the broader Australian region, including one that was over the Indonesian area," Ms Scully said.

"On average we have between 10 to 13, so it looks like we're not too far away from the average."

This season was forecast to have a below average number of cyclones due to a likely El Nino.

But even though we are back up to an El Nino alert — a 70 per cent chance of El Nino occurring within the year — the El Nino never fully developed this season.

What happened to U?

Trevor, then Veronica — wait, ABCD … RSTUV … what happened to U?

Because cyclones are named using, well, names, certain letters of the alphabet have their limitations.

To prevent reusing the same names over and over, some of the letters are grouped.

There are only so many times you can call a cyclone 'Ursula'.

The Australian cyclone naming system groups P-Q, U-V, and W-Z. Next on the list is Wallace, to be followed by Ann, Blake, Claudia etcetera.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 3 minutes 17 seconds 3 m 17 s How are cyclones named? | Weird Weather

Two at once?

Ms Scully said it was not something that you typically see, but it's not completely unheard of.

The fact they are both happening now is not a coincidence, they are both part of and connected by the monsoon trough.

"At the moment the monsoon trough has dipped over mainland Australia and the trough has tropical lows embedded within it," she said.

"At the moment the atmosphere is favourable for tropical cyclone development over northern Australia and so these lows have spun up at the same time."

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 3 minutes 20 seconds 3 m 20 s What does it take to make a cyclone? ( ABC Weather )

The water temperature over northern Australia at the moment is also "very, very warm".

A temperature of 31 degrees Celsius, according to Ms Scully.

Cyclones are fuelled by warm oceans so that is also enhancing the cyclones at the moment.

Could they collide?

Ms Scully says "no".

"The two tropical cyclones won't interact with each other, but they can interact with the weather systems further south," she said.

If we get a front coming through at the right sort of time, it could take the moisture from those cyclones and drag it over southern Australia "which is what we are going to see actually in the weekend with a cold front moving over south-eastern Australia", she said.

"The trough is really going to have a lot more moisture in it from feeding down from Tropical Cyclone Trevor."

As of Friday morning, the forecast is for Trevor to cross the Gulf of Carpentaria Coast on Saturday.

Once it crosses the coast it's expected to weaken because it will no longer be over the warm water it needs for fuel.

But just because it will weaken doesn't mean it's over.

"It's expected to track into the interior of the Northern Territory. Now, the interior of the Northern Territory has had a very dry 'wet season'," Ms Scully said.

"If you look at, say, Tennant Creek, they've only had around seven millimetres for the entire wet season. So they've seen hardly any rainfall at all over the past few months."

Trev could blow that out of the water — so to speak.

"We are expecting [Trevor] to track down towards the Barkly district towards Tennant Creek and it could drop between 100 and 150mm of rain to that region," she said.

Rain on the Northern Territory side of the border might be welcome but it would be less so further east, where they have already received devastatingly heavy rainfall this year.

Ms Scully said there is still a lot of uncertainty forecasting so far out, but at the moment it does look like Trevor — at that point it may lose its cyclone status — is expected to move from the Barkly district and then track towards south-western Queensland where it may drop some fairly heavy rainfall.

"But at the moment it does look like it is going to be in the far south-western corner," she said.

"With the last heavy rainfall event it was mostly towards Mount Isa, more in the west-north-western quadrant of Queensland."

Remember, cyclones are difficult to predict so keep up to date with the latest warnings.



Veronica came out of nowhere!

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Yes, Veronica developed quickly on Wednesday, and Ms Scully said the speed of its development is again thanks to those warm ocean temperatures.

"Another factor is that it is over water, well away from land," she said.

"What can often happen is the low pressure systems can end up interacting with the land, where it can stifle the development.

"However, this low has been well off the coast, over the water, has been getting a feed of warm, hot, moist, air, and the upper atmosphere has been supportive for its development."

Even after these storms wind down, the season isn't over yet.

Cyclone Wallace is the next name on the list, so there is still time for us to be asking "where's Wally?" before winter sets in.

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