Monster supercell storms, intense rainfall and flooding could hit anywhere, anytime in coming months, "really loading the dice" for more unpredictable, extreme weather for Australia's east coast, the Bureau of Meteorology (BOM) has warned.
It comes after unexpected severe storms caused havoc on Queensland's Gold Coast and its hinterland on Friday morning, dumping more than 300 millimetres of rain.
The super cell system, triggered by a low-pressure system off the coast, hit in the dark of the night, triggering landslides, flooding, rescues and evacuations.
BOM senior meteorologist Kimba Wong said forecasting the type of weather system was a "notoriously" difficult task.
"We did have … messaging … out that the chance of heavy rainfall would be possible on the Gold Coast region during this period," Ms Wong said.
"It did look like the main risk would be northern New South Wales but just overnight we did see that low developing a little bit further north and concentrating those higher falls over the Gold Coast region.
"These systems are notoriously difficult to forecast and the models don't do very well with pinpointing their exact position, which is really critical for the rainfall forecast.
"We did have severe thunderstorms on the forecast from yesterday, but we did see those warnings starting to be issued through the late evening hours … around midnight.
"The information was out there — I guess sometimes it's not the most accessible information.
"Of course, if you familiarise yourself with our service and where you can find the best information on our website and our app, that's the best way to self-serve as well."
Ms Wong said a combination of "climate drivers" meant severe weather could hit anytime this spring and summer.
"Obviously the [third] La Niña declaration recently, we've also got an active negative Indian Ocean Dipole which means there's warmer waters off the north-west coast of Australia – that water basically is evaporating into the air and available to rain," Ms Wong said.
"We've also got a Positive Southern Annular Mode as well … and this positive phase also does tend to lead to that wetter outlook during the spring months for much of Queensland.
"These climate drivers are really loading the dice for wetter-than-average conditions over the coming months."
Ms Wong said with the ground already so soggy, it would not take much for waters to rise.
"We're starting off the wet season from a really wet landscape already — we're seeing a lot of the catchments responding really quickly to rainfall," she said.
"The landscape at the moment is much wetter than the same time last year and the year before."
Campers caught by surprise
The intensity of Friday morning's storms caught campers at the Big4 Gold Coast holiday park in Helensvale by surprise.
Natalie Johnson and her family were at the campsite, holidaying from Victoria, when they were woken to intense rain around 1am.
Ms Johnson said it came as a shock, with waters rising in a matter of minutes.
"We went to bed and about 12am, we woke up just because the rain was so heavy and it hadn't let up," Ms Johnson said.
"We had no idea it was coming — it was about 13 minutes from seeing the water rising to the point where we decided we need to go.
"It was hell because our kids were in swags out the back so they woke up to us screaming at them to get up and get out.
"There was another guy [at the site] from Ballarat and my husband said to him, 'let's go back to Victoria where it rains normally' because we're just not used to this."
Andre Chettle is also counting his losses after battling waist-deep water at the campsite.
"We started panicking … around 1 o'clock in the morning — we didn't have time to pack all our stuff up — we got out of our swags and jumped in the car and took off," he said.
"Came back and the water was waist-high — it's just devastating, losing … mostly everything — it's just pretty sad."
'Really good time' to prepare
Ms Wong said Queenslanders and interstate travellers should stay across alerts on BOM's website, with more rounds of flooding rains likely.
"It's a really good time to be considering how prepared are you, what can you do to prepare yourself, and your property for the wet months ahead," Ms Wong said.
"If you are planning outdoor activities … during these wetter months, make sure that you're keeping up to date with the latest forecast, keep an eye on the radar and our warnings page for the latest information just to make sure you're as prepared as you can be.
"We have had quite serious flooding obviously across much of the state over the last year or so, so certainly just a situation to keep across knowing these climate drivers are in play.
"It's quite a stressful situation to be caught in."
Brisbane Lord Mayor Adrian Schrinner said sandbags were available for Brisbane residents to collect from depots in Zillmere, Newmarket, Morningside and Darra over the next two weeks.
"Another two Super Sandbag Weekends are planned this weekend and next, with thousands of Brisbane residents already taking the opportunity to prepare their home early, ahead of a potentially severe La Nina season," Mr Schrinner said in a Twitter post.
