Auckland residents and shop owners are feeling the aftermath of Cyclone Tam this morning.
Video / NZ Herald
Dozens of Aucklanders were hit by flooding inside their homes as authorities scrambled to respond to 175 callouts during “intense” thunderstorms.
City councillor and residents say the storm hit Auckland before any warning was issued, while the MetService said thunderstorms are “notoriously difficult to forecast”.
MetService could’ve warned Aucklanders sooner about incoming thunderstorms that lashed the city overnight, flooding homes and businesses as up to 110mm fell in some suburbs, WeatherWatch’s Philip Duncan says.
Waitākere councillor Shane Henderson and some residents are demanding answers as to why official warnings arrived an hour into the Cyclone Tam-fuelled storm, which also cut power to 20,000 households and delivered 750 lightning strikes to the city.
Thunderstorms are “notoriously” hard to forecast, and in this case the cells had come “one after another after another”, resulting in high rainfall amounts, MetService meteorologist Alec Holden said.
But Duncan, head forecaster at the independent WeatherWatch service, believed MetService’s warnings could’ve arrived earlier – and said the lack of open data also played a part.
“They could have been putting out alerts about this earlier, because it was developing quite clearly on the lightning maps and the rain radar maps.
“At the same time, it is tricky when they are developing literally right above you. And so there is a process of delay sometimes, as you work out, ‘Is this a really big downpour that’s going to linger, or not’.”
Lightning striking the Sky Tower during the storm that hit Auckland. Photo / Vishal Umashankar
“If we had open data that would allow councils and other government agencies, and the private sector, to all be allowed to use rain radar. Then automatic warnings would be allowed to be pushed to phones.
“And that technology has been around – at least at WeatherWatch – for the last three years, but we can’t use it here.”
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Henderson said residents were left with a “vacuum of information, no advice and no real guidance” on what was to come during the storm.
“I want to know why warnings weren’t issued a bit earlier … these things are notoriously hard to predict, but I’d just say that we err on the side of caution, and maybe MetService needs to have a look at some of the trigger points, because it was certainly pretty gnarly well before the warnings came out.”
Dozens of Aucklanders were hit by flooding inside their homes as authorities scrambled to respond to 175 callouts during the wild weather, with up to 110mm of rain falling overnight.
“We’re afraid of that kind of situation repeating, and people need to be assured that we’ve got those systems in place so that we know what’s going on.”
Asked why there was no warning before the weather system arrived, MetService meteorologist Alec Holden earlier told NZME:
“That is a very good question. Thunderstorms are historically and notoriously difficult to forecast.
“In this case the worst of it came from the fact that none of those individual thunderstorm cells were particularly notable, but it was the unfortunate incident of them coming one after another after another … to result in such high rainfall amounts.”
WeatherWatch head forecaster Philip Duncan has long lamented the lack of open weather data in New Zealand. Photo / Simon Young
Early this morning streets were swamped, motorists stranded, homes surrounded by water and power to up to 20,000 households was knocked out during the night.
A North Shore resident said it was the most severe storm she had experienced on the Shore by far.
“House shaking, no power, crying and scared 5-year-old and no warning at all.”
Another person said: “Insanely loud sound of the thunder and lightning over Bayview.”
A home surrounded by floodwaters at the intersection of Potter and Parkinson Aves, Mt Roskill. Photo / Hayden Woodward
An “arm of rain” that stretched out from the centre of Cyclone Tam was responsible for the intense downpours and thunderstorms, said Holden, the meteorologist.
Areas between Mt Roskill and Albany appeared to have been worst hit, with some areas recording between 55mm to 110mm overnight rainfall.
A Herald photographer said the worst-affected areas appeared to be around Mt Roskill and Sandringham, including Stoddard and O’Donnell Aves and Sandringham Rd.
“There was no warning at all. Residents are absolutely p***ed.”
Fire and Emergency NZ said they received more than 170 weather-related calls across Auckland at the peak of the storm.
A person staying at the Cordis in Auckland’s CBD said the thunder appeared to have set off the fire alarm and hundreds of people were in the the street.
Storm hangs on this Easter weekend
After severe rain and wind lashed the North Island, ex-tropical Cyclone Tam continues to hang on this Easter weekend, directing unstable fronts and troughs onto the northern South Island.
Meteorologists continue to keep an eye on a second weather system looming for New Zealand next week.
Ex-tropical Cyclone Tam currently lies west of New Zealand and will slowly weaken over the Easter weekend.
MetService meteorologist Samkelo Magwala said heavy falls are still on the cards for much of the country despite the weather overall “improving significantly”.
After severe rain and wind lashed New Zealand, Cyclone Tam continues to hang on this Easter weekend, directing unstable fronts and troughs on to the northern South Island. Image / Windy.com
Tasman, Nelson and northern Marlborough should expect some heavy falls today, Magwala said.
Auckland will likely receive scattered rain that could turn heavy, with possible thunderstorms before midday also likely.
“Associated fronts move southwards over the country through into Saturday, bringing heavy rain to parts of the North Island and upper South Island.
The system has also brought a wave of hot and humid air with potential for “record-breaking April temperatures” across the country.
Magwala told the Herald Wellington is in for an abnormal high of 25C today.
MetService said daytime highs today and Sunday may even reach the mid to high 20s elsewhere in the eastern and lower North Island.
Niwa meteorologist Seth Carrier told the Herald Tam’s remnants would slowly move away from New Zealand, and it might take until Tuesday or Wednesday for all the associated rainfall to end.
Debris at Cheltenham beach after strong winds and changeable weather on Auckland's North Shore. Photo / Alex Burton
Heavy Rain Warning – Orange
A number of regions still remain under heavy rain warnings today, where the risk of streams and rivers rising also remains.
