Northland braces for heavy rain and thunderstorms, flooding risk high

MetService is warning flooding may be possible for Northland as a slow-moving front brings heavy rain and the risk of thunderstorms. Photo / Tania Whyte

State Highway 1 through the Mangamuka Gorge has closed, a day after reopening.

NZ Transport Agency Waka Kotahi (NZTA) said a slip meant the highway was closed but traffic could detour via SH10.

The closure is the second in three days as Northland grapples with heavy downpours.

Motorists only yesterday celebrated the gorge’s reopening after a slip on Sunday blocked both lanes.

That slip was in a new area away from the previously completed recovery works.

NZTA said tonight’s slip nearby was no surprise.

“Contractors had been monitoring movement on the hillside following recent heavy rain and the slip was expected.”

The road would remain closed overnight and the NZTA said it would provide an update tomorrow morning.

Past weather events have severely troubled SH1 through the Mangamuka Gorge.

The 13km road was nearly obliterated by a series of 15 slips during a storm in August 2022.

Northland is going into tonight with heavy rains predicted until midnight and potential thunderstorms.

MetService earlier detected a line of severe thunderstorms near Kaitāia.

The storms were moving southwest and parts of the Far North and Kaipara were in the firing line.

“These thunderstorms are expected to be accompanied by torrential rain.”

MetService urged people to take shelter, stay off the water, move cars away from trees, drive slowly or avoid travelling.

Meteorologist Oscar Shiviti said a slow-moving front meant a large accumulation of rainfall would bring localised downpours of between 25 and 40mm per hour.

“The whole of Northland has both the risk of thunderstorms and heavy rain,” Shiviti said. “A lot of places are at the risk of flooding.”

State Highway 1 at Te Paki, Cape Rēinga, was earlier closed because of flooding.

The road has since reopened but is down to a single lane.

NZTA has urged motorists to delay their journey as no detour is available.

Cape Rēinga received 70mm of rain between midnight and 2pm today.

MetService meteorologist Devlin Lynden said April had been a wet month for Northland’s most northern location.

“The average rainfall was usually 60mm but this month alone it has accumulated 408mm.”

Lynden said Kaikohe was also sodden with 45mm of rain and Dargaville 21.6mm.

Kaipara District Council’s Ash Nayyar said there was some concern around flooding in the Dargaville township and areas like Awakino Point.

In a video he posted to social media, water could be seen endangering parked cars near the township.

Nayyar told the Advocate it was not unusual during high tide for flooding to occur, but additional heavy rain was a concern.

Some businesses, such as the Kawakawa Pharmacy, were concerned about flooding.

The pharmacy wrote on Facebook: “If the water level reaches the pipe, past experience tells us we don’t have long before we are flooded in.

“Please ensure you have a supply of any essential medications, and check that your kaumātua/kuia are covered.”

The Waiomio Valley is cut off to all cars except for 4x4 vehicles after recent heavy rain. Photo / Roddy Pihema

Bay of Islands-Whangaroa Community Board member Roddy Hapati Pihema said the Waiomio Valley was cut off for all cars except four-wheel drives.

The Kawakawa catchment, where the Waiharakeke River, Ōtiria Stream and Waiomio Stream meet, was swollen from rain.

Pihema said most local communities had resources as part of their Civil Defence response if needed.

The Kawakawa catchment where the Waiharakeke River, Ōtiria Stream and Waiomio Streams meet is swollen from recent downpours. Photo / Roddy Pihema

Civil Defence Northland yesterday said the forecast was “certainly not what we were wishing for”.

“With this heavy rain coming on top of the recent heavy rain, streams and rivers may rise rapidly. Surface flooding, slips and road closures are also possible, and driving conditions may be hazardous.”

A slip on the recently opened Mangamuka Gorge closed State Highway 1 on Sunday. The road reopened yesterday.

Flooding on Sunday reportedly saw vehicles towed and houses flooded in Pāmapūria.

MetService earlier said April had been a wet month for Kerikeri.

The Bay of Islands town has received 490mm of rainfall in April and 790mm this year alone.

The normal rainfall amount for the area in April was about 150mm.

This month had been Kerikeri’s wettest April since records began in 1978, RNZ reported. The previous record, about 60mm lower, was set in 1999.

Brodie Stone covers crime and emergency for the Northern Advocate. She has spent most of her life in Whangārei and is passionate about delving into issues that matter to Northlanders and beyond.