Weather bomb hits
Horowhenua hit by angry weather system
Aweather bomb that set up camp in Horowhenua gave residents a week of booming thunder and lightning to remember. Horowhenua was in the thick of an angry weather system that assaulted much of New Zealand's west coast for five days.
The weather system was characterised by a large amount of thunder and lightning and caused widespread flooding due to a series of heavy and spasmodic downpours, with the odd tornado and hail storm thrown in too.
MetService meteorologist Tui McInnes said there were 123,009 lightning strikes recorded.
Already this month had the second highest monthly tally of lightning strikes since observations began, he said.
While most of the lightning was off the coast in the Tasman Sea, there were still 30,650 strikes on land, along with the obligatory thunder claps.
Through the worst of it Horowhenua residents were warned to stay indoors and limit any nonessential travel.
Nerves could finally catch a break when the rough weather started to abate by the middle of this week.
McInnes said there were three main contributing factors that made the storm so stubborn: an atmosphere prone to having low pressure, southwesterly polar outbreaks and warmer-than-normal waters for most of the country.
“The last week has seen us under a ‘planetary trough', which means the atmosphere prefers low-pressure systems over the country resulting in an almost-continuous barrage of lows and fronts,” he said.
“When we talk about polar outbreaks, we refer to a weather system where cold air moves north, over warmer water. This is important as it creates instability, which is required for thunderstorms to develop.”
McInnes said a marine heatwave had a significant impact too, making the skies electric.
“As mentioned with the polar outbreaks, colder air moving over warmer ocean is important. Throw in water that's warmer than usual into the mix, and you've added a whole lot more energy into the system. It's like doubling the baking powder in your muffins.”
The relentless rain and severe wind gusts caused problems in Horowhenua.
On Sunday and Monday, when the weather system was at its worst, it seemed as if a siren in town was going off every half hour, as emergency services responded to a high number of calls for help.
For much of the storm there was surface water down every street. In addition to full rivers and streams, saturated soils combined with wind also meant the odd landslip and fallen tree.
Horowhenua Chronicle editor Janine Baalbergin had water flood her garage and lap up to her back door. Like many properties in town, her backyard was completely under water for much of the weekend.
Several homes at Foxton Beach had a narrow escape on Monday night as a swollen Manawatu¯ River clashed with high tides and threatened to send sea and river water through their front doors.
Huge waves riding a high tide were blown up the river mouth by severe westerly squalls clashed with the raging floodwaters heading out to sea that were only given more oomph by the gravitational pull of a full moon to the east.
High tide arrived in darkness
around 8.30pm on Monday night. By the time it began to recede, just two homes reported damage, while the Manawatu¯ Marine Boating Club near the wharf had also taken in water.
Foxton Beach fire chief Rodney Caldow was part of the emergency response and said if the floodwaters had risen half a metre or more, it could have been a far different story.
“We planned for the worst while hoping for best,” he said.
That included installing a preventative flood protection barrier across Hartley St and placing more than 500 sandbags in front of the lowest-lying properties.
The preventative flood barrier sock made of thick grey PVC and blown up with water went some way to protecting properties along Hartley St and Dawson St from further flood damage.
Caldow said the barrier was stored at the boat club and until now had only been used in annual practice drills.
The Moutoa Floodgates, monitored by Horizons Regional Council, were opened around 10.30pm that night to ease pressure on the lower reaches of the Manawatu¯ River.
As the rain subsided, they were closed the following day at 5pm.
Caldow said although the narrative suggested this kind of weather happens once every 50 or 100 years, it was the second time in the past six years that houses at the beach were threatened by flood.
Mayor of Horowhenua Bernie Wanden praised the efforts of those who put the barriers and sandbags in place, and those involved in emergency services and the emergency response.
“Our emergency services partners, contractors, lines people and council’s Civil Defence Emergency Management (CDEM) team worked effectively and collaboratively over a number of days,” he said.
Civil Defence Emergency Management continued to monitor the situation at Foxton Beach earlier this week, concerned that the ensuing high tides could cause further flooding.
The river did breach the boat ramp and flooded the carpark at the Manawatu¯ Marine Boating Club again the next day, although the water was not as high as 12 hours earlier.
Horowhenua CDEM controller Lisa Slade said by then the worst was over, although the wild weather and high rainfall had put pressure on HDC infrastructure.
Water treatment plants and stormwater and wastewater pump stations were pushed to the limit processing significants amounts of stormwater.
Tokomaru and Levin water treatments were temporarily offline for a time due to high turbidity.
Mayor Wanden thanked the community for their water conservation efforts over the weekend after a call went out to limit water use.
“After the weather event we experienced last June, where we had critically low levels in our water reservoir and water turbidity (muddiness) in the O¯ hau River meant our water treatment plant was unable to treat water for a period of time, we thought it best to take a precautionary measure and ask people to conserve water,” he said in a statement.
“Thank you to everyone who followed our advice yesterday and reduced their water usage.
“Thank you also to those who stepped out to help one another by clearing drains or checking on their neighbours.
“It is always encouraging to see such a strong sense of community.”
Power issues at Foxton Wastewater Treatment plant had to be rectified by electricity contractor Electra, whose staff were all over the district through night and day trying to restore power.
Electra spokesman Baden Berry had urged the community to keep away from any surface flooding or puddles as there may be electrical equipment hidden from sight. Power had to be restored to 33 lines in the Kāpiti-Horowhenua region, and linesman also worked to restore rural transformers that were impacted by lightening
A gas flare that extracts and dispels gas from the Levin landfill stopped working in high winds and was still offline early this week.
Specialist contractors, gasfitters and Envirowaste staff were on site in an effort to fix it.
It was due to a minor landslip. Top soil and grass has shifted on one of the cells and disconnected some pipework from one of the gas wells onsite, although the clay liner on the cell has not been effected.
HDC chief executive Monique Davidson said staff were working to find a resolution. Further updates will be provided once the situation was better understood.
The exposed gas does not cause any immediate danger to the community, she said.
Council’s Animal Welfare team partnered with HUHA to offer support to any animals impacted by the adverse weather, making available stock trailers, temporary yards and a food supply for animals in need.
Where there was widespread surface flooding in Levin HDC contractors deployed sucker trucks and sandbags, to affected areas like Goldsmith Cres, Denton Rd, Arapaepae Rd, Central Service Lane, Lancaster St, Bishops Rd in O¯ hau, MacArthur St, Byrd St, Fairfield Rd, Burn St, Okarito Ave, Kawiu Rd, Kimberley Rd/Speldhurst East, Wakefield Rd, Matai St, Edinburgh St, Highbury Drive, CD Farm Rd, Cambridge St, Argyle Ave, Kennedy Drive, Oxford St, Beechwood Ave, Easton Way, Lynch Grove and Buller Rd.
The weather forced the closure of Trig Rd at the weekend.