A farm in Waiwhare, Hawke’s Bay, recorded an incredible 730mm of rainfall during Cyclone Gabrielle, which at its peak unleashed 250mm of rain an hour into the gauge.
The 730mm figure is more than double what the peak forecasts for Hawke’s Bay were expecting ahead of the cyclone and helps explain the huge flows that breached the banks of the Tūtaekurī River in Napier on Tuesday February 14.
A Davis weather data logger set up on the Te Konini farm recorded 643.6mm over 24 hours on the Tuesday and 730 mm altogether over Tuesday and Wednesday according to Tom Lane, sheep and beef farmer and general counsel and commercial director at Rockit Global Ltd.
Lane said he also had a few plastic fence post rain gauges with a capacity for 100mm that were filled up pretty quickly, but this was the only weather station he had running that could record the entire event.
“We average about 1100mm in a year, so that was pretty phenomenal,” he said.
“We were getting a rate of about 250mm per hour around 5am on the 14th.”
He said it was possible that it could be an unreliable reading, so he was trying to get in touch with the manufacturer, Davis, to help pull more data out of the data logger so Hawke’s Bay Regional Council can look at it and it can be of use.
According to Niwa, the highest amount of rainfall recorded in a single hour in New Zealand is 134mm at a gauge near a waterfall on the Cropp River, in Kakapotahi, in the South Island.
The record for the most rainfall over 24 hours is 869mm, recorded at the same Cropp River site according to Niwa.
A Hawke’s Bay Regional Council spokesman said the council could not respond to specific questions about the Te Konini farm data at this time.
The spokesman said the council was working very hard to verify all the data gathered during the cyclone so they could answer questions about it in due time.
Lane said there had not been much of an effect from Cyclone Gabrielle on the farm relative to other places.
“We are fortunate to be well above, 100 metres above the Tūtaekurī,” Lane said.
“Because we are up high, the water just sheeted off.”
Lane shared photos of a pump shed on lower ground in the area surrounded by floodwaters on Tuesday and in the aftermath.