Wind warnings are in place for the Auckland Harbour Bridge alongside the risk for “quite intense thunderstorm activity” for parts of the North Island this afternoon.

The strongest wind gusts on the bridge are likely to reach 75km/h to 80km/h until 7pm, triggering an amber alert, NZ Transport Agency Waka Kotahi (NZTA) said.

Drivers are urged to take extra care and be prepared for the possibility of lane closures or reduced speed limits.

MetService meteorologist Devlin Lynden told the Herald a threat of thunderstorms remains for parts of the North Island after a tornado and squally thunderstorms ripped through Northland this morning.

A man in his mid-80s was trapped and hurt inside his flipped motorhome after it was struck by a mini tornado that tore through a Tauranga Bay, Northland campground.

“There’s still definitely the risk this afternoon and evening of some quite intense thunderstorm activity,” Lynden said.

A front will move over the Bay of Plenty this afternoon, bringing a moderate risk of thunderstorms there.

The electrical storms may bring localised intense bursts of heavy rain and small hail.

“As the west to southwest flow becomes established, there is a moderate risk of thunderstorms about Auckland and Coromandel Peninsula during the afternoon, and for western areas from Waikato to northwest Tasman, including coastal Whanganui, during the afternoon and evening,” MetService said.

Drivers are being asked to take extra care and be prepared for the possibility of lane closures or reduced speed limits.

Risks for Auckland

Auckland is under a moderate risk of thunderstorms as cooler, showery conditions push in from the west.

“We’re expecting definitely the potential for the odd lightning strike and thunder in the area,” Lynden said.

Heading toward evening, that risk will diminish as the weather is set to ease for the rest of the afternoon.

Aucklanders are also facing highly localised strong wind gusts that could reach 80-100km/h in exposed places.

“At the moment, we don’t plan on putting out any watches or warnings, but we’ll continually monitor if there is a more significant cell that pops up.

“There’s potential that one place in Auckland might see some quite strong gusts, whereas others might not,” Lynden said.

Road closures and Auckland Harbour Bridge impacts

Motorists travelling across Auckland Harbour Bridge were urged to drive to the conditions, look out for electronic message boards indicating lane closures or speed-limit reductions, and stay within their lane while travelling across the bridge, NZTA said.

Drivers of high-sided vehicles and motorcyclists were advised to avoid the harbour bridge and use the western ring route on State Highways 16 and 18.

However, motorists using this alternate route were earlier warned they could face delays after a serious incident closed westbound lanes on State Highway 18 between Greenhithe Rd and Tauhinu Rd, including the Tauhinu Rd westbound on-ramp.

Police said a person with serious injuries was taken to hospital.

Traffic was building in the area and police advised motorists to allow additional time to reach their destination.

Tornado lashes Northland

Earlier today, particularly in Northland, there were intense downpours and a reported tornado, Lynden said.

“There were some heavier showers, but the key was that it was quite a brief line of kind of squally type thunderstorms.

A caravan at Tauranga Bay, Northland was flipped by the mini tornado. Campers say it rolled about six times.

“There were also some quite intense gusts associated with that this morning.

“Areas in the Northland area recorded gusts of up to about 75km/h, perhaps a bit more in some more exposed places.”