A red severe weather warning was only issued for Hawke's Bay on the day the cyclone made landfall. Photo: Supplied / Dawson Bliss
MetService could have upgraded weather warnings for Hawke's Bay to red the day before Cyclone Gabrielle hit in early 2023 - but faced opposition from the regional council, according to the agency's chief meteorologist.
The first phase of the inquest into the deaths of 19 people in the storm and Auckland floods is focusing on the warnings given to the public, and the emergency response.
The weather forecaster issued a red severe weather warning for Hawke's Bay on 13 February, the day the cyclone made landfall.
Chief meteorologist Chris Noble said MetService wanted to issue the warning the day before but Hawke's Bay Regional Council was opposed, based on confidence in its flood modelling.
"One thing we've learned through this event is that red warnings are significant beyond just the flood modelling that might feed into that discussion and ultimately it's MetService's decision whether to go red or not."
Noble said MetService's severe weather team had discussed upgrading to a red warning with the council's hydrology team on the morning of Sunday 12 February, ahead of its first issue of warnings about 10am that day.
"The hydrologists were opposed to a red warning being issued, citing high confidence in their flood modelling which indicated no major concerns."
MetService is tasked with communicating weather forecasts and warnings but does not undertake flood modelling.
It upgraded the orange warning for the region from orange to red on Monday 13 February at 3.15pm.
"I cannot say exactly what changed other than acknowledging the event was underway so the meteorologist would have been monitoring in real time... but I can't say for certain what led to that change from orange to red."
Noble said in hindsight, MetService should have issued the red warning a day earlier, on the morning of 12 February.
"It's definitely our preference that everyone agrees that it is a good idea to issue a red warning because of the significant impacts that we do understand it will have within communities," he said.
"I would say this is probably touching on one of the biggest learnings for us from these events that ultimately, MetService has that decision to make and should make it if necessary, even if the other party doesn't agree."
Matthew Mortimer-Wang, the counsel assisting the coroner, asked if there was enough information to justify a red weather warning.
Noble said red warnings did not have a technical threshold of rainfall because they were designed to alert people to weather's extreme impact on their region and were linked to flood assessments.
"It places everyone in a difficult position if those models don't adequately capture the intensity of an event at a specific location," he said.
Hawke's Bay was one of the cyclone's worst-hit regions but there were no alerts or warnings before the Esk River burst its banks, flooding the entire valley in the early hours of 14 February.
There have since been multiple inquiries into the actions of authorities before and during the cyclone. All of the investigations found failures in New Zealand's emergency management system.
The various reports made more than 100 recommendations, including the creation of an early warning system for the public.
The inquest on Tuesday heard how councils use a range of different information to predict flooding.
Counsel assisting the families of the deceased Jane Glover asked why MetService believed the different flood forecasting systems were a "serious vulnerability".
Noble said a range of agencies, MetService, NIWA and councils all owned weather stations but there were restrictions on sharing that data with one another.
He also said the way in which the 16 regional councils develop forecast and model future flooding varied.
"Across the country there's an uneven playing field for how flooding is forecast and modelled, we're aware that councils all have their own processes and that various councils will use different types of rainfall information to inform their flood prediction and their warnings," Noble said.
"What we're really calling out there is a better linked up system that's using the same inputs to the warnings with the expertise feeding through to the flood modelling."
Noble said that would be "advantageous across all of New Zealand, independent of the size of the council or their ability to pay for additional information".
At the time of the cyclone, he said Hawke's Bay Regional Council used one single model from MetService for its flood modelling, while in other parts of the country NIWA assisted other councils with their flood predictions using a model different to that of MetService's.
"It's just an example of how things are done differently in different regions and I think it would be a stronger system if the playing field was levelled and we all had a well integrated system using the same information right from the rainfall to the warnings to the flooding prediction itself."
NIWA manager for climate, atmosphere and hazards Nava Fedaeff started to give evidence late Tuesday afternoon, about the data the institute provides about the weather and potential flooding.
The National Institute of Water and Atmospheric Research is a Crown Research Institute that as of this month, has merged with GNS Science to become Earth Sciences New Zealand.
The inquest continues on Wednesday and hearings are set down for about six weeks, split between Auckland and Hastings.
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