'Staggering amount' of rain fell during Cyclone Gabrielle, fresh data shows

Wednesday, 1 March 2023

Twice this year, Peta Komaru Morgan has spent countless hours shovelling silt from his home and garden after cyclones.

The full scale of Cyclone Gabrielle’s downpour on Hawke’s Bay is only now being realised as data is retrieved from weather stations that lost contact.

And it seems it was bigger than the previous benchmark, the 1980s' Cyclone Bola which devastated the region.

The Hawke’s Bay Regional Council has now recovered data from weather stations that lost communication during Cyclone Gabrielle on February 14.

Rainfall surpassed forecasts in multiple areas, including by more than 250mm in one area, said council marine, air, and land science team leader Dr Kathleen Kozyniak.

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Steve Wheeler has silt up to two metres deep blanketing his Esk Valley property, plus thick slash which came down the Esk River and stopped at his lounge windows.

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Aerial shots of Esk Valley after Cyclone Gabrielle.

Two monitoring sites in the Porangahau catchment in southern Hawke’s Bay, which were there during Bola, had “significantly more rainfall during Gabrielle”, she said.

“Twice as much rain fell on those sites during the most intense 24-hour rainfall period of Gabrielle than during the most intense 24-hour period of Bola.”

Inland from the devastated Esk Valley, Glengarry recorded 546mm of rain, 400 mm of which fell in 12 hours. It had the region’s highest reading.

Exposed areas of the southern Hawke’s Bay coast reached 450mm during the cyclone.

“The eastern area of Wairoa is similarly exposed and was the other part of the region, alongside Glengarry, to get more than 500mm of rain.

“Gabrielle delivered about 320mm of rain to our Newstead site, in the western hills of the Ahuriri catchment near Puketapu, which is about one-third of the usual annual rainfall there – most of it falling within 24 hours.”

Council chairperson Hinewai Ormsby said the new data confirmed what those who lived through Gabrielle knew.

“This data reinforces the staggering amounts of rain we received versus what was forecast. It helps us understand how heavy the rain was in a relatively short period of time.

“While numbers such as these won’t provide comfort to those who have lost a loved one or a home or a business, but they do put into context just what an extraordinary event Cyclone Garielle was.”