Heidi Groom from the SES said people in the Tweed and Byron areas would be receiving emergency alerts on their phones about flood safety on Sunday night, and there was now a wait to see whether an early morning downpour in excess of 200 millimetres would arrive at the same time as the spring tide.
“If it comes into the catchment then, it will arrive at the river mouth at the same time as the high tide and that will result in coastal inundation,” Ms Groom said.
The bureau’s flood manager Justin Robinson said flood warnings are in place from the Manning River through to the lower Mid North Coast.
“These are dynamic weather systems and you should always expect the unexpected,” Mr Robinson said.
He said rainfall could also be higher than is being forecast, with warnings likely to ramp up in the next 24 hours.
NSW SES Commissioner Carlene York said earlier that crews have been inundated with calls for assistance in northern NSW this weekend.
“We’ve received 700 calls for assistance, last night we had 200 calls,” she said.
It has also conducted four flood rescues and is on standby for waters to recede in one area to rescue animals that have been trapped by rising waters.
SES crews have also been evacuating caravans in particularly at-risk areas as a precaution and are door-knocking and assisting with preparation in those communities.
Ms York said additional crews, including some from Sydney, have been sent up to provide additional support.
“We’re making sure we have as much resources up there as possible,” she said.
She also warned people against dangerous behaviour around floodwaters.
“I’ve seen some of the vision, not only of people driving in flood waters but children playing in flood waters. This water is fast flowing, it’s not like it normally is in those rivers,” Ms York said.
“Be very careful, it is quite deceptive and it can change quite quickly.”
Byron’s Bay’s main beach has been extensively sandbagged by council workers due to coastal erosion but no properties were under threat on Sunday.
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Pallavi Singhal is a data journalist at The Sydney Morning Herald
Angus Thompson is an Urban Affairs reporter for The Sydney Morning Herald.