Cold blast for South Island, ferries cancelled

Otago Daily Times

29-04-2025

Periods of heavy snow down to 800 metres is forecast for the Canterbury High Country, south of the Rangitata River, from 6pm today until 10am tomorrow. Snowfall amounts may approach warning criteria.
The snow would be welcome news for ski fields, MetService meteorologist Mmathapelo Makgabutlane said.
"At this early stage, I'm sure we'll definitely take any snow that we can get. However, it is quite unseasonal, so in terms of the ski fields, we'll definitely be crossing our fingers for more snowfall as the season goes on.
"For places like Canterbury, it is looking like quite a long-lived wet weather story."
MetService said the prolonged rain came after a wet start to the year, and warned it could lead to rapidly rising rivers, surface flooding and difficult driving conditions.
Christchurch City Council contractors had been preparing ahead of the downpour, clearing gutters, sumps, stormwater grates and beach outfalls.
The heaviest rainfall was expected in the western Port Hills and the southern part of Banks Peninsula, the council said.
"It's a good idea to clear your rain guttering and drains and if you know there are leaves blocking sumps or drains by your property, it would help us if you could remove them, and put them in your green wheelie bin.
"Our stormwater network is designed to cope with heavy rain and our road network is also part of our stormwater network playing an important role during wet weather events. In most parts of the city our roads have been designed as secondary flow paths for stormwater so in heavy rain its normal to see some flooding on our roads."
The council was also managing water levels in the Ōpāwaho Heathcote River.
"Residents along the upper and mid-reaches of the river can expect fluctuations of water levels at any time before, during and after the rainfall event, even during periods of dry weather. This is to reduce peak flood levels during the rainfall event by maximising the use of the storage volume in the basins," the council said.
Makgabutlane said by the weekend, conditions should start clearing up.
"It is expected to be at least a couple of days. And so today, Wednesday, we're expecting everything to really start kicking off. Tomorrow, Thursday, will be another day to keep a close eye on, as well as Friday.
"But it does look like as we head into the weekend, most of the country should be rid of that weather and by Sunday, things are looking pretty good across the country."
As a rule of thumb, big wind 🌬️ = big waves 🌊.Significant wave heights are forecast to reach 7-10 meters offshore.Combined with a King Tide, the risk for coastal erosion & possible flooding is elevated.
Stay up-to-date with marine forecasts & warnings from @MetService. pic.twitter.com/7UCAE28TIN — NIWA Weather (@NiwaWeather) April 29, 2025 Ferries cancelled
Strong wind watches have been issued for the Buller, Grey, Westland and Nelson Lakes districts, the Marlborough Sounds in the South Island and and Wellington, along the south coast, including Wairarapa north of Castlepoint, in the North Island.
Southeast winds may approach severe gale in exposed places.
MetService has issued heavy swell warnings for the 33-hour period between midday tomorrow until 9pm on Friday.
Waves of 6 metres were forecast off Wellington - Cape Terawhiti to Turakirae Head from 3pm tomorrow until noon on Friday, while swells rising to 7 metres were expected off Wairarapa - Turakirae Head from midday tomorrow until 9pm on Friday.
"This weather system that's bringing all of this weather that we're expecting is also going to be generating some large swells, but also the wind's generating some large waves on top of that and causing all sorts of problems and disruptions," Makgabutlane told RNZ's Morning Report programme.
Interislander said it had cancelled crossings from 8.30pm today 2.30am on Friday, and there would be extra sailings put on over the weekend to accommodate passengers. More cancellations were likely on Friday if conditions did not improve.
Bluebridge was cancelling sailings from 1.30pm today and all of tomorrow. Home Tunnel closures
The Homer Tunnel on the Milford Road (SH94) in Southland is closing from 6.30pm to 3am for maintenance works from today until May 2, then from May 3-23 from 6pm until 3am.
"No public access during these closures due to heavy equipment operating in tunnel."
- Additional reporting APL