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Weather warnings upgraded for Auckland, Northland; Evacuation preparations begin

Author
NZ Herald ,
Publish Date
Wed, 17 Aug 2022, 11:13AM
Photo / NZ Herald
Photo / NZ Herald

Weather warnings upgraded for Auckland, Northland; Evacuation preparations begin

Author
NZ Herald ,
Publish Date
Wed, 17 Aug 2022, 11:13AM

Threats of heavy rain over the coming days have prompted weather authorities to issue a "red warning" and Civil Defence to declare a State of Emergency for the South Island's battered West Coast region.

Westport residents in low-lying areas that flooded in February this year are being advised that that they should act today to lift valuables, make arrangements for their pets and be prepared to self-evacuate.

Niwa has warned of a "48-hour deluge" for the northern and western South Island, where some locations could see two to four times their normal August monthly rainfall.

Severe gales are also expected in some areas including Northland which earned an orange warning from MetService. Gusts of up to 120km/h in exposed places are expected from 9am tomorrow.

Heavy rain warnings for Auckland and Northland

MetService has upgraded weather warnings for the upper North Island and has heavy rain warnings for Northland, Auckland and Great Barrier Island.

Between 110mm to 140mm of rain is forecast in Auckland and Great Barrier Island in the 28 hours from 10pm tonight until about 2am on Friday.

"Heavy rain may cause streams and rivers to rise rapidly. Surface flooding and slips are also possible and driving conditions may be hazardous," the weather authority said.

The same heavy rain warning is in place over Northland - but which last longer; from the 35 hours from 7pm tonight until 6am on Friday.

More rain is expected to fall over the region. Locals are told to prepare for between 150mm to 220mm of rain to accumulate, especially in the north and east.

Peak rates of 15mm to 25mm/h are on the cards tomorrow.

Buller Civil Defence Controller Al Lawn said people who had evacuated in the past knew the importance of having time to plan and prepare, so he urged them to take the initiative, consider their own circumstances and act today in case the situation deteriorated.

"We have done a lot of work to mitigate the effects of the rain and protect critical infrastructure, but we recommend that householders who were flooded in February this year look at their own situation and take action today," he said.

"We are constantly assessing the information on river levels and the impacts of the rainfall, and at this stage we are not requiring a general evacuation. But people need to be aware that there is a significant amount of rain still to fall and the situation could change."

Where possible, people who plan to self-evacuate should arrange to stay with family or friends.

Anxious and stressed residents have started preparing their homes with sandbags and other measures in the Buller district.

Buller district deputy mayor Sharon Roche told TVNZ's Breakfast: "At this stage, we're just asking residents to be prepared. A lot of them have already started to sandbag and...prepare their homes.

"At this stage, there [is] no plan of evacuation. But obviously, if people feel safer by moving out to friends or family to higher ground, then absolutely we would encourage that."

Roche said surprisingly, there was not much rainfall overnight.

"There were times when there were some heavy showers then other times when there was no rain at all."

Roche said one advantage authorities had was time. Extra pumps had been brought in, and extra support and Roche said diggers were out working in critical spots known to flood in the past.

"We're well prepared - as prepared as we can be."

Roche said they are due to get a briefing and update on the situation some time this morning.

Asked how residents were feeling, Roche said: "People are anxious and stressed - there's no doubt about that."

That was particularly the case for those whose homes or properties had been badly damaged in previous weather events, she said.

The West Coast is one of the regions in line for the "atmospheric river" weather event, which one expert says could be more damaging than otherwise as it comes after an exceptionally wet winter.

Atmospheric rivers are large and extremely high plumes of moisture that move in the atmosphere from the tropics to the mid-latitudes, where New Zealand is located.

When they hit another weather event or New Zealand's mountainous terrain, vast amounts of water vapour is squeezed out, falling as heavy rain or snow, Niwa meteorologist Tristan Meyers said.

Experts say it is likely this weather event is influenced by climate change.

MetService issued the red warning - reserved for the most extreme weather events where significant disruption is expected - for Westland and Buller where up to 500mm and 550mm of rain is expected to accumulate, respectively.

Large parts of the rest of the country are also expected to get drenched by the extreme weather event - including Northland, Waikato, Taupō, the Tasman District, Marlborough and Mt Taranaki.

Meyers said two bursts of rain were expected, from Tuesday-Thursday and then again from Saturday-Sunday, affecting primarily the South Island.

"All up, over a month of rainfall could fall for large parts of the West Coast, Canterbury High Country, Tasman, Marlborough and Nelson.

"This will lead to slips, and possibly flooding for some South Island rivers."

It would also melt snow which could exacerbate riverine flooding in some areas, he said.

Meyers said heavy rain was also headed for parts of the North Island, particularly Northland, Taranaki and Bay of Plenty, with the most intense downfall expected on Wednesday.

University of Otago senior lecturer in geography Dr Daniel Kingston said although this specific weather event had not been analysed regarding the influence of climate change, it was "more than likely playing a role".

Average air temperature had warmed by slightly more than 1C over the past century and as the atmosphere warmed it could hold more moisture, increasing the likelihood for extreme heavy rainfall events such as this.

"Sea surface temperatures around New Zealand are also warmer than average right now, which can further amplify these sort of events."

Kingston said this event could be more damaging because it comes on top of an already exceptionally wet winter.

July was the wettest on record while more than 40 locations have experienced record or near-record rainfall, he said.

"The ground is already very wet with limited capacity to absorb further rain."

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