'Phenomenal' day of thunderstorms continuing Saturday with severe warnings for parts of Auckland

Saturday, 15 December 2018

Video shows the many lightning strikes of the thunderstorm over the south Auckland/Thames area.

A 'phenomenal' day of thunderstorms on Friday will continue Saturday with severe thunderstorm warnings for parts of Auckland.

Friday saw intense rainfall, flooding and around 27,000 lightning strikes.

On Saturday, MetService is warning of severe thunderstorms in areas of Kaipara, Waitākere and Rodney, west and north of Auckland.

At 12.37pm, MetService's weather radar detected severe thunderstorms near Helensville, Wellsford, Kaukapakapa, Kaipara Flats, Woodhill, Ahuroa, Parakai, Okahukura Peninsula, Makarau, Glorit, Tauhoa, Shelly Beach and Port Albert.

**READ MORE:

Flooding near the Mobil service station on Manukau Rd, Pukekohe around 1pm on Saturday.

* Wild weather calls Fire and Emergency to 40 jobs in one night in South Auckland

* Thunderstorms, hail, rain hammer South Taranaki**

The thunderstorms were moving south and expected to hit from 1pm.

'These thunderstorms are expected to be accompanied by very heavy rain, MetService said.

South Taranaki has been hit with rain, hail, lightning and thunder.

'Very heavy rain can cause surface and/or flash flooding about streams, gullies and urban areas, and make driving conditions extremely hazardous.'

At 4.50pm, the New Zealand Transport Agency tweeted that there was flooding between the intersections of Restall Rd and Pulpit Rock Rd in Woodhill.

'Please take extra care.'

Flooding hit the Pukekohe and Franklin areas in south Auckland around 1pm on Saturday.

MetService meteorologist Tui McInnes said there was a 'brief' thunderstorm right over Pukekohe and to the east in the early afternoon but it wasn't severe enough to warrant a warning.

Dramatic photo of the storm captured by Manurewa resident Faye Wong.

McInnes said there was about 10-20mm of rainfall per hour in the area but it was to be expected with the storm.

Earlier, MetService was warning of a chance of severe thunderstorms on Saturday for much of the North Island. The area at risk of being hit hardest was western and central Northland and northern Auckland.

In that area, MetService calculates there's a high risk of severe thunderstorms, with rainfall intensity of up to 50mm an hour, gusts of up to 80kmh and hail of 20mm or more in diameter.

'The combination of another warm, humid day with light winds will allow daytime cloud buildups to again produce scattered thunderstorms over the North Island today,' MetService said.

For Auckland down through the Central Plateau, there's a moderate risk of severe thunderstorms on Saturday afternoon and evening, with rainfall intensities up to 40mm an hour and gusts to 60kmh.

Hail pounded areas of South Taranaki during a 'phenomenal' afternoon and evening of thunderstorm activity across much of the North Island on Friday.

Friday's thunderstorm activity continued overnight, with MetService warning around 1am of a risk of severe thunderstorms in parts of Auckland, Waikato and the Coromandel Peninsula.

'There was a band of thunderstorms that was going through,' MetService meteorologist Rob Kerr said on Saturday morning. 'They (meteorologists) were monitoring the situation. They were just concerned it was increasing in vigour as it got going.'

In the end, Auckland city avoided the worst of the rain that fell late night and into the early morning, but it was a different story in the Hauraki Gulf, with Waiheke Island recording 38.5mm between 11pm-1am.

At night the sea could become more favourable for thunderstorms because it didn't cool as quickly as the land, Kerr said.

Much of the North Island had rain at some point during Friday afternoon or evening, with intense downpours cropping up in many areas.

'It was a phenomenal afternoon,' Kerr said. 'In 24 hours we had something like 27,000 lightning strikes.' Only a few hundred of those were in the South Island.

There were reports of hail the size of walnuts. 'It starts to become really dangerous then.'

The thunderstorm activity was the result of a combination of low-level moisture – the fuel – brought in by northerlies, and a cool air mass going over the top, increasing the contrast in temperature. 'We had these really heavy rainfalls associated with that.'

Fire and Emergency was called to about 40 callouts in south Auckland on Friday night, with flooding in Manurewa and Pakuranga.

At one weather station in south Auckland, 36.5mm was recorded from 9-10pm, with a further 12mm in the following hour.

There were also reports of intense thunderstorms with large hail from South Taranaki on Friday afternoon. Kerr said that at Pohokura Saddle in eastern Taranaki 63.5mm of rain was recorded from 4-6pm, with 52.5mm of that in the first hour.

Sunday is expected to be a quieter day, with the North Island expected to be mostly fine after some morning cloud, although there could be some afternoon or evening showers in the north and east.

Low cloud is forecast for the east coast of the South Island, and isolated afternoon and evening showers are expected in the Canterbury High Country and Marlborough ranges.

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