Forecasting models for MetService are being reviewed and set for improvement according to chief executive Stephen Hunt, after the failed weather reporting of the Auckland Anniversary floods.

MetService recently concluded its weather forecasting models performed badly before the extreme rainfall that devastated Auckland on January 27 and need to be urgently improved - with internal staff correspondence revealing disbelief at the level of inaccuracy.

“Substantial changes” were also required to the agency’s severe weather warning system in the aftermath of the unprecedented deluge, according to a summary of the review obtained by the Herald under the Official Information Act.

Talking to The Mike Hosking Breakfast on Tuesday, Hunt said teams were in a real state of flow on the day. 

"Actually on that day, I was in the forecasting room standing behind the lead forecaster and I was watching them perform, deciding...really intensely scrutinising all the information they're getting from the models, using their expertise," said Hunt.

"Even then they didn't predict the exact intensity and volume of the rain and that's a big lesson for us."

Hunt also said it must be remembered that "every country in the world is experiencing the impacts of climate change". 

"The whole atmosphere is changing, the warmer ocean is driving moisture and energy into the atmosphere and there's more intensity everywhere," he said. 

The chief executive said the forecaster is looking at options where it can improve its reporting abilities, including the process of taking inspiration from how overseas forecasters tackle the same problems. 

Hunt said his chief of science has just returned from an overseas tour of the three main global modelling centres, with the goal of understanding how they operate and how they incorporate elements such as AI in weather reporting. 

"It's all very exciting," said Hunt. 

"All countries have an intense focus on this, including ourselves, so we'll be right up there with leaders of the future."

The Herald obtained Microsoft Teams chats between MetService staff which show how they reacted to the realisation on that Friday night that their models had been inaccurate.

“This is just madness,” one employee posted at 11.44pm, after reviewing unprecedented rainfall measurements across the city.

“The models WERE NOT going for these amounts,” another wrote.

“I still can’t believe it,” another said the next morning.