On Sunday Alfred began moving as a tropical low from Queensland's Bribie Island, across the coast, and inland towards the state's southwest on Sunday.
But there is still bad weather more to come, as forecasters expect up to 700mm of rain and destructive gusts to continue through to Monday.
On Saturday around 5pm a military truck rolled and another tipped on its side near Lismore as they were carrying 32 Australian soldiers being deployed to assist in the storm and flood response.
Thirteen soldiers were hurt, six seriously.
One truck rolled several times into a paddock and the other tipped over as the driver attempted to avoid the first vehicle, NSW Police said.
The injured were taken to local hospitals. Prime Minister Anthony Albanese called them "heroes who were on their way to help people in need".
The Bureau of Meteorology on Sunday warned of swollen rivers across southeast Queensland and northern New South Wales leading to flash flooding.
"Today is all about the rainfall that's likely to be experienced around southeast Queensland and far northeastern NSW," said senior meteorologist Dean Narramore.
Isolated rainfalls of up to 400mm are expected on Sunday alone with another trough from Central Australia dragging the weather activity inland over northern NSW.
"By Wednesday, the weather system will finally shift all this wet weather to coastal parts of NSW and clearing mid to late week while southeast Queensland should start to see conditions easing from persistent rainfall on Monday," Mr Narramore added.
The Wyaralong Dam, an hour south-west of Brisbane, has started overflowing due to heavy rain.
In NSW, multiple flood warnings remain in effect for the Tweed, Richmond, Wilsons, Clarence and Bellinger rivers.
The weather event has already claimed one victim, with a body found believed to be of a 61-year-old man.
The man's ute was swept into floodwaters at Megan, about 25km north of Dorrigo in NSW on Friday.
He was able to climb into a tree about 30 metres from the riverbank but was swept away before emergency personnel could reach him.
Emergency crews rescued 17 people who'd driven into floodwaters in the past day, as the SES urged people not to risk their lives by ignoring the strict warnings.
More than 45 people have been rescued so far in the latest flood event.
Around 15,000 people throughout NSW are still under 36 emergency warnings, with NSW North Coast Minister Rose Jackson noting 800 have sought shelter in the state's 21 evacuation centres on Sunday.
But across the border in southeast Queensland, there are signs of life slowly coming back to normal, even though power outages are still affecting residents with 100,000 losing electricity overnight.
There are presently 243,000 outages across the National Broadband Network with most of them in Queensland.
Grocery giant Woolworths said some of its stores are reopening and shelves are being restocked.
Public transport, excluding trains and Gold Coast buses, is resuming while shops, supermarkets and service stations will begin opening on a case-by-case basis.
