Authorities have issued an evacuation warning for Lismore amid a major flood prediction that could see the town's levee overtopped as a search for a missing man is set to resume on Monday.
The State Emergency Service (SES) said the Wilsons River was likely to exceed the moderate flood level of 7.2 metres on Sunday night, rising to a major flood level of 9.7 metres early on Monday morning.
The SES warns the river could continue to rise, reaching a possible height of 10.6m on Monday.
North Coast Incident Controller Steve Patterson, said the region was seeing widespread rainfall of between 150 to 250mm, including isolated heavy falls of up to 500mm.
"That's quite significant and potentially life-threatening conditions," he said.
"We've certainly started issuing evacuation warnings and we do have multiple agencies on the ground.
"They will be commencing door knocking and we'll keep people updated throughout the night."
The CBD and South Lismore are protected from one-in-10-year floods by a levee, however it overtops when the gauge at the rowing club reaches between 10.2m and 10.6m, depending on the rainfall.
About 4:00pm on Sunday, NSW Police said officers near Brewster Street and Uralba Street in Lismore's CBD saw and heard a man calling for help from nearby floodwaters before losing sight of him.
"Police Rescue entered the water and searched the area however, the man has not been located," they said.
"A search of the surrounding area was undertaken involving local police and the NSW State Emergency Service."
Rising floodwaters forced the suspension of the search which police say will start again on Monday morning.
Earlier on Sunday, authorities issued evacuation orders for the village of Tumbulgum, along the Tweed River, amid major flooding.
The area is effectively isolated as roads in and out of the village have been closed.
In addition to Lismore, evacuation warnings have been issued for the Brunswick River at Mullumbimby, areas near Maclean on the Clarence River, as well as Uki, Chinderah and Fingal Head near the Tweed River.
The SES is urging people in the north-east corner to avoid non-essential travel with moderate to major flooding forecast along the river systems.
Over the past week there have been at least 40 flood rescues in northern New South Wales.
The Bureau of Meteorology is predicting localised six-hourly rainfalls in excess of 250 millimetres in parts of the Northern Rivers, and between 80 and 110mm more widely.
It is part of the same system that has inundated much of South-East Queensland in recent days and led to the deaths of six people.
Tumbulgum evacuation order
An evacuation centre has been set up at the Salvation Army Centre at Banora Point for Tumbulgum residents.
The SES issued the evacuation order just after 9am, with residents directed to leave via Terranora Road.
They were reminded that once floodwaters rose, access to water, sewerage, power, phones and internet might be lost and it might be too dangerous for emergency services to carry out rescues.
'It's a dynamic situation'
Authorities are warning moderate to major flooding is possible in the Wilsons, Richmond, Tweed, Clarence and Orara rivers.
Evacuation warnings are in place for Uki, Chinderah and Fingal Head near the Tweed River and Maclean near the Clarence River.
SES spokesperson David Rankine said the Orara River at Coutts Crossing could reach major flood level tomorrow, but that it was contingent on the amount of rainfall in the catchments.
Moderate to major flooding is possible at Lismore overnight from Sunday into Monday.
Flood not forecast to reach 2017 levels
BOM senior hydrologist Ailsa Schofield said while the Wilsons River in Lismore was forecast to reach a major flood level, it was still expected to be below the level in 2017 caused by ex-tropical cyclone Debbie.
"We have not seen those rainfall totals in this area, but I would like to stress that the rain that we've seen in Queensland has been torrential and that system is moving to New South Wales.
"So the current situation is for major flooding to occur in Lismore, but we are actively monitoring those rainfall levels and we'll provide updated warnings if required."
There are 550 SES volunteers in the state's north and there have been 70 flood rescues since the weather event began on Tuesday.
Premier Dominic Perrottet has pleaded with people to follow evacuation orders.
"We recently had a death on the Central Coast in floodwaters," he said.
"Our strong message today to people up in the north, particularly where those evacuation orders or warnings are in place or issued, please follow the instructions from the SES."
Business prepare for major flooding
Businesses in the Lismore CBD have been busy packing up stock and sandbagging to prepare for flooding.
The SES said moderate to major flooding of the Wilsons River at Lismore was possible from tonight into Monday.
Shop owner Sharon Poles said many business owners were getting in early to prepare.
She said they did not want a repeat of the devastating 2017 flood which caught many off guard.
"It was such a devastating time in 2017; the sheer amount of debris that we saw on the streets."
Hairdresser Telea Byrne said the past 24 hours had been stressful.
She said her stock was secure thanks to family and friends and the generosity of a man who donated space for local businesses to store their goods.
"I can go home and not stress that I'm going to come back to nothing, so it's good, it's nice," Ms Byrne said.
"[The good Samaritan] doesn't want anything in return; I wish I could do more for him, but that's the good thing about Lismore — when these things happen, it's what the community's about, we all band together."
Flooding scenarios for Lismore
Mr Rankine said there were two main issues with flooding in Lismore.
The first was the riverine flooding from the Wilsons River, which had the potential to top the levee as it did in 2017, he said.
But he added that flash flooding of the CBD could occur when there was significant localised rainfall.
"When the water gets to 5.5 metres [in the Wilsons River], council shuts the floodgates and turns the pumps on.
"We saw in December 2020 that there is the chance that once those floodgates are shut and we get significant rainfall within the CBD … we can see some localised flooding in the CBD [because] water trapped in there can't get away."
Landslip makes parts of road inaccessible
Further south, two landslips on Waterfall Way near the towns of Thora and Dorrigo on the Coffs Coast have made parts of the road inaccessible.
The state Member for Oxley, Melinda Pavey, said recent upgrades to the road could only do so much against strong conditions.
"You cannot ever stop that from happening in such a mountainous area … it's frustrating, there's no doubt."
