Entering a third straight La Niña, Helensvale caravan park owner Theo Whitmont says uncertainty around flash flooding and heavy rainfall has changed the way he does business.
His park has been evacuated due to flash flooding multiple times over the past three years, including in September when an unexpected downpour of about 300 millimetres forced visitors to flee at 2am.
"We know what to do when we know there's going to be inundation," he said.
"Where it becomes difficult is when we go to bed at night and get told there's a small chance of 30mm of rain overnight, and it turns out we get 300.
"You've got to be a bit of a Nostradamus to know what's going on."
While forecast heavy rainfall of up to 300mm in some areas did not eventuate on the Gold Coast over the weekend, Bureau of Meteorology forecaster Livio Regano said everything was lined up for a summer of floods.
That spells bad news for Mr Whitmont, who said "to be in business you need some predictability; uncertainty is death".
'New landscape' for Gold Coast
Mr Whitmont said a section of his park prone to flooding usually held about 50 families, but he has been cancelling or rearranging bookings if heavy rainfall is forecast.
"It's a new landscape for everybody on the Gold Coast," he said.
He said drainage had been improved on the site and staff trained for emergencies, but he wanted greater certainty from forecasters.
"That's no criticism of the Bureau of Meteorology, I think they're trying as hard as they can," he said.
"We can work with the known, it's the unknown that's very difficult to work with."
Mr Regano said "the atmosphere is fluid" with such weather events difficult to predict and track.
"It's like trying to work out when a river flows over a bed of rocks, we know the rules that work out where all the drops go but you try tracking them all," he said.
"Every single particle of air is being tracked by mathematical equations, known as primitive equations, and they have solutions that are incredibly dependent on the initial conditions.
"Even with the best possible technology, things just go off the rails and that's just how it is."
Messages are 'genuine'
On Saturday, Mayor Tom Tate told residents to "brace [themselves]" for isolated falls of up to 300mm.
But levels fell short, with Southport recording 51mm between Saturday and Sunday morning, and Upper Springbrook receiving 113mm.
But Cr Tate later said that warning was "based on the data we had".
"It's probably more important that we over-prepare than under-prepare," he said.
"If you under-prepare, the damage is done; to rewind that, you cannot."
He said Gold Coasters should avoid complacency, with more flooding alerts likely.
"I'd say to Gold Coasters be patient about it," he said.
"My messages are genuine and mother nature can change."
