Wainui River at Herbertville in the Tararua District at 8.53am on Tuesday. Photo / Horizons Regional Council webcam.
Up to 70mm of rain fell in one hour as torrential thunderstorms, followed by prolonged heavy rain, flooded more than a dozen roads across the region.
A community hall and church were swamped by floodwater in Central Hawke’s Bay, while in nearby Tararua, the heavy rain cut power and cellphone coverage and stranded a coastal community.
By 12pm on Tuesday a flood alarm on the Wainui River, which runs through the coastal community of Herbertville, had been triggered, Civil Defence Manawatu Whanganui said.
The Herbertville area had lost power and cellphone coverage and the campground was being prepared for evacuation as a result, it said.
Ākitio was “cut off” because of slips on Coast Rd and River Rd.
It was estimated the largest slip would be removed by the end of Tuesday.
MetService on Tuesday morning issued orange heavy rain warnings for all of Hawke’s Bay south of Tūtira until 3am on Wednesday and Tararua until midnight on Tuesday.
MetService said to expect 80mm to 110mm of rain to accumulate about Hawke’s Bay’s ranges and coastal hills, and lesser amounts elsewhere, in addition to rain that had already fallen by 9am on Tuesday.
It said the warning amounts were unlikely near the coast north of Cape Kidnappers.
Heavy rain fell across the region overnight on Monday, with severe thunderstorms striking coastal areas south of Cape Kidnappers.
Several roads were closed in Central Hawke’s Bay, and the council advised people to stay away from beaches and river mouths and avoid streams and drains on Tuesday morning as a “king tide” hit.
At 2.15pm, Central Hawke’s Bay District Council said the Tukituki, Waipawa and Pōrangahau river levels were expected to continue to rise into the evening, but not to a level of concern, based on the most recent modelling information it had received from Hawke’s Bay Regional Council (HBRC).
Coastal areas, particularly in Omakere and parts of Elsthorpe and Mangakuri, had been hit hardest.
Six Central Hawke’s Bay roads were closed because of flooding and slips, including for a time the northbound lane of State Highway 2 near Ōtāne until a local cleared a drain about 7am.
Omakere School was closed for the day and the Omakere Hall was pictured surrounded by floodwaters.
Images seen by Hawke’s Bay Today showed the beloved Mangakuri Station Chapel was also hit by flooding.
Hawke’s Bay Regional Council’s telemetered rainfall figures said 95mm of rain had been recorded at Omakere from midnight to 9am on Tuesday.
A Hawke’s Bay Regional Council spokesperson said on Facebook they were monitoring conditions related to the orange heavy rain warning south of Tūtira.
“Our flood forecasting suggests the rainfall and runoff will fill the main rivers approximately to the top of banks, but should not cause issues beyond riverbanks.”
Tararua District Council advised people to avoid all unnecessary travel in the district on Tuesday.
At 1.30pm, nine roads were closed across Tararua, and multiple roads were down to one lane.
A fast-moving storm cell passed over the coastal Tararua area around Ākitio and Herbertville on Monday night, bringing “very heavy rainfall” in a short period, Tararua District Council said.
The Ākitio weather station recorded 70mm of rain in just one hour between 9pm and 10pm.
“While the main rain band initially moved north earlier in the evening, rain has since resumed across much of eastern Tararua, east of the Puketoi Range.
“We are asking people to avoid unnecessary travel and check conditions before heading out.”
Herbertville was without power and cellphone coverage, though internet access was still available in some areas, the council said.
“We’re working with the Herbertville Civil Defence Group and encourage Herbertville residents with needs or concerns to reach out to us on 06 374 4080, through a Facebook message or through Antenno.”
One family in Ākitio chose to relocate to a safer location as a precaution, but at this stage, no mandatory evacuations have been required, it said.
Overnight on Monday, Manawatū-Whanganui Emergency Management Group monitored rainfall and staffed a Group Emergency Coordination Centre overnight.
In a 1.26am update, the group said the weather was “quite volatile and unpredictable”.
People in Herbertville had reported rain, thunder and lightning storms in the area.
According to Horizons Regional Council‘s environmental data monitoring network at 7am on Tuesday, the Ākitio River at Cadmus Bridge had 150mm of rain since 1pm on Monday, Wainui River at Wimbledon had 100.2mm, and Owahanga River at Owahanga Station had 114.4mm.