A local state of emergency for the Buller District has been declared this afternoon as West Coast residents batten down the hatches and prepare to evacuate as torrential rain begins to hammer the region.
West Coast mayors are urging their residents to be prepared and avoid travel amid red alert rain warnings - the most serious weather warning there is.
The Buller District Council said the state of emergency that was declared around 2.30pm is to allow Civil Defence controllers to direct and coordinate personnel, material and other resources made available to it, and to give them access to extraordinary powers to respond to an emergency.
A large-scale response is kicking into gear, with West Coast Emergency Management setting up centres in Greymouth, Hokitika and Westport.
Westport civil defence controller Bob Nixon said the rain was starting to pour down intensively at about noon.
MetService yesterday issued the rare Red severe weather event, warning that the amount of rain in the Westland and Buller ranges until at least Friday was expected to cause dangerous river conditions and significant flooding. Slips and floodwaters were likely to disrupt travel, making some roads impassable and possibly isolating communities.
Haast has recorded 80 millimetres of rain from about 8pm yesterday to 8am today - almost twice as much as it had for the month of January.
The predicted heavy rain falling over State Highway 6 in South Westland since the early hours of today was causing some surface flooding but so far no serious slips or highway delays, says Waka Kotahi NZ Transport Agency.
South Westland rivers are rising rapidly and there is surface flooding between Haast and Hokitika on low-lying areas of highway. There is also surface flooding back into Otago, between Haast and Makarora.
“Following the MetService Red warning, as a precaution, Waka Kotahi and our maintenance contractors yesterday moved civil contractors and machinery to several locations in the South Westland area,” says Moira Whinham Maintenance Contract Manager for Waka Kotahi on the West Coast.
“This means that once the storm has passed, we can restore any areas of damage as quickly as possible.”
MetService is predicting more than half a metre of rain near the mountains, inland Westland, from the early hours of Wednesday to Thursday evening, with thunderstorms continuing through the week. At the glaciers there could be 300mm of rain and up to 250mm on the coast.
In Westland from 2am today until noon on Thursday: expect 500 to 750mm of rain to accumulate about the ranges (especially between Otira and Fox Glaciers), and 150 to 250mm near the coast. Peak rates of 30 to 45mm/h about the ranges, with thunderstorms.
In Buller, from 1pm today until 6pm on Friday: there will be periods of heavy rain, with 300 to 400mm of rain set to accumulate about the ranges, and 150 to 200mm near the coast. Peak rates of 20 to 35mm/h about the ranges, with thunderstorms possible.
"Even by the wet standards of Westland, that is an incredible rainfall event," MetService meteorologist Angus Hinds says.
In July last year, after a similar red warning - almost half of Westport's residents were evacuated after major flooding inundated much of the town, causing millions of dollars in damage, and damaging hundreds of homes.
This year, dry summer soils, high tides, and forecast thunderstorm downpours were expected to exacerbate the danger.
Westland mayor Bruce Smith said the rain began overnight, and high tide was expected just before 1pm today.
"We've got a lot of snow that's melting and that's feeding the rivers, we've got obviously the front that's coming through but that significant part is we've the driest period of weather that we've had for many years and the ground is hard as hell.
"The rain is going to run off really quickly and that's going to create a big issue, potentially slips on roads and things like that."
Rain warning for Otago headwaters, strong winds for Canterbury
Meanwhile, Orange heavy rain warnings have been issued for the Canterbury and Otago headwaters and other western South Island areas.
A strong wind watch is in place for the Canterbury High Country from 11am to 10pm today. Northwest winds may approach severe gale in exposed places at times.
MetService meteorologist Lewis Ferris told RNZ today the weather system very stationary over the next few days bringing with it a long period of heavy rain.
"It looks like it could hang around as heavy persistent rain through to Saturday [in Westport] and that's much the same story as we move into Buller as well."
The West Coast would see a lot of washouts and potentially a lot of trees falling on hills, he said.
"The West Coast has been very dry in January and that rain really is going to create issues. Streams that are running extremely low or even just rivers that are running extremely low are going to rise very rapidly once those intense rainfall [downpours] do start to accumulate along those ranges."
Be prepared: Buller mayor
Buller mayor Jamie Cleine said the escalation of the rain warning heightened the importance of the region being prepared and planning was well under way for what could be a significant event for the West Coast.
Residents were being warned to pack an emergency getaway bag, make sure their cars were filled with petrol, and be prepared for evacuations at any time.
The heavy rain was due to coincide with high tides and there was concern for those in the north of the Buller district in places like Mohikinui, Seddonville and Karamea.
All the ingredients were there for the weather event to be similar to the deluge that caused widespread flooding last July, with almost half of Westport's residents evacuated from their homes, and at least 100 homes rendered unliveable by the floodwaters, Cleine said.
The 2021 flood event remained fresh in people's minds, he said.
"There's no doubt about it, that's a clear cause of additional anxiety as these sorts of events unfold, so we're very conscious of it. Our flood recovery hub was put on notice earlier this morning to expect increased inquiry and anxiety levels from the clients that they're working with."
It was important those in Buller monitored the official channels for further instructions - the West Coast Emergency Management Facebook page and on local radio stations, Cleine said.
"Start thinking about a getaway bag and what emergency supplies you might need and obviously think about where you might head if the call was to come to evacuate at some point."
Cleine said they were planning for the worst.
"What we learnt from July was that some of our traditional evacuation centres are sort of less than ideal in a town flooding scenario so a lot of work going in yesterday out side of town, effectively up on the terraces which obviously presents some logistical problem around where people can shelter."
Rural halls, sheds on farmland will be better than nothing and ready to go later today, he said. "They'll be high and dry."
Chorus was sandbagging roadsides in some places, and stormwater drains would be checked too, he said.
"Consider some of your friends and family that may be less able to act for themselves and make sure they've got a plan and are connected in with the information network as well."
Warning to stay off roads
Westland mayor Bruce Smith said he anticipated flooding, road outages and possibly worse.
"We're just trying to get the message out to people to ensure that they fill their car up tonight - make sure it's full of petrol, ensure their standby plant has got fuel and that they've got basic groceries for two or three days, you know, it's basic Civil Defence stuff."
Warm winds and snow melt combined with a massive rain event and dry ground conditions meant it had the potential to cause quite a problem on the coast, particularly around Fox and Franz Josef glaciers, Smith said.
"We've had such a dry spell, the ground is so dry, the waters just going to roar off it and head to the sea as quick as it can."
An emergency operations centre had been stood up at the council building in Hokitika and Smith said he hoped people would stay off the roads on Wednesday unless travel was absolutely essential.
"I think there's a high chance there's going to be a number of unexpected slips and we don't want people getting trapped in between slips or you know, getting caught in them unnecessarily."
Waka Kotahi/ NZ Transport Agency has warned motorists across the South Island to avoid non-essential travel to the West Coast.
"If you have to travel, we're wanting you to take extra care but obviously if you can reassess your plans, that's what we are recommending in line with the Civil Defence advice as well."
State Highway 73 through Arthurs' Pass and SH6 through Haast Pass were expected to be the most affected.
"We're always just worried about slips and vegetation falling down on the road and obviously flooding, surface flooding on to the road."
Waka Kotahi Journey Manager Tresca Forrester said Westland was a difficult place to clear slips in a hurry, especially if there was ongoing rockfall or vegetation blocking a highway.
There are several places with no mobile phone coverage in South Westland and people are encouraged to let their family and friends know if they are going to be travelling and what their expected timeline is.
Tracks closed
West Coast tracks are closed due to weather conditions.
The Department of Conservation closed the Copland Track near Fox Glacier, as it was due to receive more than 100 millimetres of rain in 24 hours.
The Hokitika Gorge Walk, Pororari River Track and Bullock Creek Road tracks were all closed and DOC also closed its Lake Paringa and Ottos/MacDonalds campsites.
The Heaphy Track was closed until Saturday and the Paparoa Track was closed for a week.
All visitors with hut bookings would be contacted by the DOC booking team and offered a full refund.
- RNZ and ODT Online
