16 Aug 2018

Tolaga Bay: Council says MetService didn't warn about deluge

11:53 am on 16 August 2018

Gisborne District Council says MetService failed to forecast the intense rain that caused damaging flash flooding in Tolaga Bay over Queen's Birthday weekend.

Logs wash up on Tologa Bay beach after flooding in the area.

Logs wash up on Tolaga Bay beach after flooding in the area. Photo: Photo / John Boynton

The downpour on 3 and 4 June caused people to be evacuated from their homes and flooding washed tonnes of forestry debris onto roads and damaged homes and properties.

As much as 60mm of rain an hour was recorded over the weekend, but the council had no idea it was coming, a report by the council said.

MetService did not issue a severe weather warning for Gisborne, nor did it forecast the intense localised rainfall in the Tolaga Bay catchment.

"It was not until the rain arrived and was accurately recorded in the rain gauge network that the model was able to predict a significant event," the report said.

A review of its flood monitoring systems had been carried out but concluded there was nothing more the council could have done as it relied on MetService to provide the basic data, it said.

MetService said it was "rare" for such as event to go undetected, but it did happen sometimes.

"The 3-4 June event was relatively small and incredibly localised.

"None of the global or in-house high resolution weather models used when forecasting rainfall, gave any indication of the significance of this event which is why only watches and not warnings were issued.

"Whilst it is rare for an event like this to go undetected by the models, with New Zealand's difficult terrain it can, and does, unfortunately happen," MetService meterological operations general manager Ramon Oosterkamp said.

Gisborne District Council will discuss the report at its meeting today.

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