'Humongous' rainfall stuns weather experts

Nearly 80mm of rain fell on Tauranga yesterday. Photo/George Novak

A ''humongous'' amount of rain fell in Tauranga on Monday night, a forecaster says.

A whopping 79.4mm of rain drenched the city yesterday.

MetService meteorologist Claire Flynn said most of the heavy rain fell between 8pm and 9pm, when 18.2mm was recorded.

"That's humongous. You don't often see that kind of rainfall anywhere in the country. Maybe on the West Coast at some point. That's massive," she said.

Just 4.6mm of rain fell during the rest of the evening.

Flynn said the wet weather was expected but such a significant downpour was not.

"We did have a low risk for downpours that ended up happening right at the end [of the risk period]."

MetService yesterday morning forecast heavy rain from 4pm to 6pm.

"We had a rain band that was affecting the northern half of the North Island. It was a bit of a wave - it eased off a bit and came back."

Flynn said the rain band was also slower to move on than expected.

"It was not typical at all. I don't expect that would be a national record because you do occasionally get more than that but it's certainly not common."

MetService's highest record for rainfall in Tauranga was 67mm in one hour in May 2005.

The second highest rainfall tally for a day in Tauranga in the past month was 14.2mm on August 9 and the total for the past month so far, including yesterday, was 140.2mm.

In July, Tauranga recorded 124mm of rain.

WeatherWatch's Phillip Duncan said the 18.2mm was a lot.

"Subtropics [are] to blame, along with a blocking big high to our east that kept that rain stuck and slow over the Bay of Plenty," he said.

MetService forecaster Angus Hines said yesterday was expected to be the best day of the week before a succession of low-pressure systems moved on to different parts of the country.

But as winter drew to a close, the country would be hit by back-to-back low-pressure systems starting in the North Island on Wednesday.

Potholes filled

New Zealand Transport Agency has filled a series of potholes created on Monday night during one of the heaviest downpours Tauranga has experienced.

There were reports of holes on State Highway 29A, Hewletts Rd and Takitimu Drive.

However, the agency would not confirm how many potholes were reported, or the location of them.

Bay of Plenty Transport System Manager Jack Hansby said potholes were not unusual at this time of year when there was higher rainfall.

"Potholes are caused by the pumping action between tyres on the road and water. They are more common on roads where there is more traffic, particularly trucks."

Mr Hansby said he understood the frustration such incidents caused motorists.

"If people see potholes we encourage them to call us on 0800 44 44 49 so they can be fixed."