Kanin Petera, an 11th-grade student, lost his life on 9 May 2023 when a flash flood trapped him inside Abbey Caves near Whangārei during an educational excursion, while Northland was under an orange heavy rain warning.
Did You Know? Karnin ‘Tino’ Petera was 15 years old when he died in the Abbey Caves flash flood, according to coverage.
Coroner Criticises Computer-Generated Forecasts
Coroner Alexander Ho released findings last week criticising MetService hourly rainfall forecasts and questioning the validity of updates generated by computers without human moderation before publication. According to the findings, the rainfall updates may not have aligned with the true forecast on the day of the trip.
“The consequences of relying on inaccurate weather data differ depending on the purpose,” Coroner Ho said in his findings. “Not receiving the expected forecast rainfall for one’s lemon tree is inconvenient. Being caught outside in a thunderstorm during a high-risk outdoor activity is dangerous.”
At the start of the excursion on Tuesday morning, the forecast called for light-to-moderate rain, which a MetService meteorologist characterized as the sort of precipitation where someone would begin to notice the absence of a raincoat.
“The 12.5 millimetres of rain which the Monday 9 pm forecast predicted between 1 to 2 pm on Tuesday was no longer,” the coroner said. “Instead, the Tuesday morning forecast predicted rainfall of between 1 and 4 millimetres per hour, each hour, between 7 am and 5 pm.”
Discrepancies Between App and Website Disclaimers
Coroner Ho raised concerns about why MetService publishes hourly numbers at all, given they are computer-generated and not verified against other forecasts before release. The coroner argued that potential differences between app, website, and true forecasts were not made clear enough to the public.
“In other words, for an observation or forecast published in the ‘9 am’ column, the relevant observation or forecast rainfall is for the hour leading up to 9 am, not the observation or forecast rainfall at 9 am,” Coroner Ho explained.
When digital platforms display unmoderated hourly data alongside conflicting disclaimers, time-pressured decision-makers often rely on the most reassuring numbers available rather than the most authoritative ones.
Chris Noble explains how MetService prioritises weather warnings
MetService chief meteorologist Chris Noble stated that severe weather watches and warnings should always take precedence over other forecast information. According to Noble, watches and warnings are prominently displayed across the website and app to help people recognise severe weather and take appropriate action.
Noble reported that MetService had already been working on communication improvements when the coroner released the findings. Since the incident, MetService has added a message advising users to rely on written forecasts and icons produced by meteorologists if they differ significantly from hourly model data.
Questions about the Abbey Caves trip and MetService forecasts
What warning was active during the Abbey Caves trip?
An orange heavy rain warning was in force for Northland on 9 May 2023 when the Whangārei Boys’ High School trip took place.
How do MetService hourly forecast columns indicate time periods?
According to the coroner’s findings, an observation or forecast published in a specific hour column refers to the hour leading up to that time rather than the hour following it.
What prior findings were issued regarding the incident?
WorkSafe found back in 2024 that the tragedy was preventable, noting that the school’s risk assessment required trip cancellations during heavy rain warnings.