People have been accused of acting like “vultures” as a heavily populated Australian coastal region braces for a cyclone to hit for the first time in 50 years.

Authorities have called for calm before the storm, with panic buying widespread in southeast Queensland ahead of Tropical Cyclone Alfred’s arrival.

The category two system is set to turn toward the southeast coast on Tuesday and impact landfall in the coming days, triggering destructive winds, heavy rainfall and flooding.

More sandbagging sites opened across the region as people attempt to safeguard their homes and lined up for hours.

About 100,000 sandbags have been collected in the past three days in Brisbane alone as it bunkers down for Alfred.

Rainfall and strong wind gusts have begun ahead of the cyclone expected to make landfall between the Sunshine Coast and Brisbane on Thursday evening or Friday morning.

Supermarket shelves have been stripped bare in some stores as locals brace for impact, prompting a call for calm.

Panic buying brings back memories of COVID. Photo: Facebook

Sunshine Coast Police Superintendent Craig Hawkins said there were no supply issues and no need to panic buy ahead of the cyclone’s arrival.

“Get what you need but be respectful of others who also need supplies to get through this,” he told reporters on Tuesday.

The worst of Alfred’s impact, once it makes landfall, will hit the state’s southern flank, including Brisbane, the Gold Coast and NSW’s Northern Rivers.

Towering waves up to 10 metres are predicted and one metre of rainfall could be dumped on those regions.

Gale force winds could smash the coast, reaching extremes of 150km/h and bringing down trees and powerlines.

Beaches and university campuses have closed, ferry services have stopped and Gold Coast theme parks are set to shut down from Wednesday as Alfred looms.

Emergency services, telco providers and Energex crews have bolstered the region.

“Today’s a really, really key day for everyone … today’s the day that we’ve got to get those logistics right so I’m asking people to take it seriously,” Queensland Premier David Crisafulli told ABC Radio Brisbane on Tuesday.

Heavy rainfall of up to 400 millimetres is forecast this week leading to widespread flooding in southeast Queensland and NSW’s northeast.

Council workers help Gold Coast residents collect sandbags. Photo: AAP

NSW’s Northern Rivers is again in the firing line three years after flooding claimed five lives and destroyed homes.

“Obviously those communities have already gone through massive amounts of flooding in recent years,” NSW Premier Chris Minns told ABC.

“This is the last thing that they want to hear but we are asking them to be prepared … for the worst and hope for the best.”

On Tuesday, gale-force winds and rain started to batter heavily populated Australian coastlines in two states.

The weather system is moving slowly about 560 kilometres east of Brisbane as a category two and is forecast to slow further before making a U-turn towards the Queensland capital.

“It would actually start to move directly towards the coast of Brisbane and the Sunshine Coast later today,” Bureau of Meteorology’s Jonathan How said on Tuesday.

Rainfall and strong wind gusts are already beginning ahead of Alfred making landfall between the Sunshine Coast and Brisbane on Thursday night or Friday morning.

Ferry services on the Brisbane River have been halted so vessels can be moved out of the river ahead of Alfred making landfall.

There are already large waves along with coastline, including one swell of more than seven metres on North Stradbroke Island overnight and waves of more than 9.5 metres off Brisbane.

Further south, there were swells of more than six metres at several Gold Coast beaches, including Palm Beach and the Southport Spit, while the Tweed offshore monitoring station recorded 8.95-metre waves on Monday.

“The location of landfall will be critical because we are expecting to see the worst of the impacts, or most significant impacts, on the southern flank of the cyclone,” How said.

“That does include places like Brisbane, the Gold Coast, and also the northern rivers.”

The northern rivers and south-eastern parts of Queensland had 40 millimetres of rain on Monday night – a total that is expected to easily be topped in coming days.

How said 200-400 millimetres was expected on the Sunshine Coast later in the week, while parts of the Gold Coast and northern rivers could get 500-700 millimetres.

“That includes places like Lismore, Mullumbimby, down towards Cape Byron and also inland parts of the Northern Rivers, as well,” he said.

The deluge is expected to bring widespread, moderate to major flooding in south-east Queensland and NSW.

Flood watches are current for the two states and multiple rivers.

The destructive winds are forecast to be prolonged and cause significant damage to properties and trees as Alfred draws closer.

Residents are already preparing for the weather system with 100,000 sandbags collected in the past three days in Brisbane.

Tropical Cyclone Alfred’s path as it heads towards Brisbane. Source: Bureau of Meteorology

Alfred will be the first cyclone to cross the coast so far south since 1974, when Zoe made landfall at Coolangatta. It was just weeks after Cyclone Wanda had triggered record Brisbane floods that claimed 16 lives.

There have been some near misses since with Nancy in 1990 and Oma in 2019.

One expert warned that many more people and significant infrastructure would be “in the firing line” when Alfred hit.

“What we have seen since then (1974) particularly at places like the Gold Coast is a significant amount of development on flood plains and along the coast,” Natural Hazards Research Australia CEO Andrew Gissing said.

“It could be a significant disaster event. We are right to be taking this seriously.”

People have been warned to leave or prepare for the worst, sparking panic buying in some areas.

Energy supplier Energex has also warned that people in south-east Queensland should prepare for three days without power.

“We are ready to respond to any impacts from severe weather when it is safe to do so. Gale-force winds and floods can cause extensive damage to the electricity network, so be prepared for extended power outages,” the company’s website stated.

Gissing was confident regions in Alfred’s path had enough time to prepare, potentially reducing damage and increasing safety as long as they took the cyclone risk seriously.

Queensland Premier David Crisafulli urged people to be prepared but remain calm. He has also urged supermarkets to restock as soon as possible, amid reports of shelves emptying due to panic buying.

“Today’s a really, really key day for everyone, for individuals, and indeed, more broadly as a state, and today’s the day that we’ve got to get those logistics right,” he told ABC Radio Brisbane.

“I’m asking people to take it seriously.”

-with AAP