Heatwave generates problems
Weather trouble is brewing in the warm seas around New Zealand.
Forecasters say it is only a matter of time before the marine heatwave in our corner of the southwest Pacific turns an otherwise innocuous rain-bearing system into something more damaging.
While there are plenty of signs of change ahead, it is too early to pinpoint just when that weather will arrive here.
Many parts of New Zealand have dried out in the past month, because of persistent ridges of high pressure across and around the country.
With the exception of the west and far south of the South Island, no significant falls are expected to relieve the dry spell in the next week to 10 days.
MetService meteorologist Georgina Griffiths told Stuff changes in the atmosphere were all around, but might take time to directly affect New Zealand.
The country was coming to the end of one of its broad weather patterns, which tended to last six weeks and rarely any longer.
‘‘We don’t normally hold a ridge across us for six weeks. But it looks like we are in for a pretty significant change this month.’’
Air pressure in the Tasman Sea and south of New Zealand was forecast to fall over the next two weeks.
That would eventually bring more Philip Duncan, Weatherwatch
rain and please farmers, she said.
Blue Skies Weather forecaster Tony Trewinnard said ‘‘all the ingredients’’ were in place for wet and stormy weather across the country.
‘‘But it just doesn’t want to happen at the moment.’’
Greater weather activity and energy in the atmosphere above the tropics and sub-tropics would eventually feed south towards New Zealand.
‘‘Also, the Tasman Sea is significantly warmer than usual. It shouldn’t take a great deal to push all that water vapour into any developing storm. All it needs is a trigger to start the process.’’
From this weekend, for the next two weeks, the weather systems would be more active than in the past month, Trewinnard said.
WeatherWatch managing director Philip Duncan said New Zealand was ‘‘sitting in a little bubble of high pressure’’, squashed between developing storm systems to the north and south. ‘‘There’s definitely trouble brewing. ‘‘This is the biggest change I’ve seen in the tropics for six months. It’s a really big change and it’s happening really quickly.’’
Duncan was keeping an eye on three tropical lows which could bring rain to northern parts of New Zealand during the next two to three weeks.
Fronts were moving on to the south and west of the South Island but weakening as they did so, with some rain falling in the far south and on the West Coast. But for many in central parts of the country there was little or no rain on the horizon for the next fortnight.
The dominance of intense, rainbearing low pressure systems ‘‘might be more of an issue once we get to March’’, he said. Hamilton’s run of scorching days has put major strain on the city’s power grid and left some residents relying on generators.
Around 600 properties were affected and some were without electricity for more than eight hours as residents reached for the air conditioner last Tuesday as Hamilton cracked a record 32 degrees celsius.
There’s little end in sight to the temperatures and possibility of outages, with the MetService forecasting a run of temperatures in the upper 20s well into next week.
WEL Networks said faulty cables caused the cuts, and while it’s a rare occurrence, the lines operator can’t guarantee it won’t happen again. Around seven generators were used to power homes in Pukete, Chartwell, Nawton, Te Rapa, Melville, and Fairfield over the last week.
General manager WEL Services, Mat O’Neill, said the organisation had experienced only one other similar incident, back in 2017. He said the faults were isolated to a particular type of cable.
Melville resident Judith Green was told by a WEL Network worker that there was an ‘‘overload of people using appliances to cool down’’, such as fans and air conditioning units.
A large generator appeared on Manor Place late last week and supplied power to its residents while work was done to fix the faults, Green said.
Green said the power cut was inconvenient – her main concern was about meat in the freezer. Her household wasn’t able to sleep that night because of the heat so she was awake when power was restored around 2.30am.
O’Neill said properties were placed onto generators within two hours of the outages occurring. They then experienced a short outage, of less than an hour, while they were being switched back on to their regular supply after the faults had been fixed.
‘‘There’s definitely trouble brewing. It’s a really big change and it’s happening really quickly.’’