The MetService has issued orange heavy rain warnings for the Westland District from 9pm on Friday, and for Buller and parts of Tasman from the early hours of Saturday.
The already sodden West Coast is tipped to receive 150 to 200mm of rain about the ranges, possibly up to 250mm near the glaciers, and 70 to 120mm nearer the coast. Peak rates of 40 to 50 mm/h are expected on Saturday morning about the ranges.
A local State of Emergency was declared in Westland last weekend after torrential rain lashed the district and caused rivers to rise rapidly.
The 'bizarre part of it all'
But Westland District Council mayor Helen Lash said they had already recovered from last weekend's rain and tourists are being put off from visiting.
"We dry out pretty quickly down here ... [With] the rains that fell in the mountains that always takes a while to work its way down, but the rivers are back to their usual levels and everybody's dried out and recovered."
She said local councils and emergency management would be looking in particular at the predicted volumes of rain in the front.
"At the moment there's some pretty horrifying figures there of millimetres per hour in particular areas, and it all comes down to whether that eventuates and nobody has the crystal ball on that."
The emergency meeting would give them an updated forecast, she said.
"It's what we do here quite regularly. Is it concerning? Once we get it defined into where it's likely to fall and the volumes it's going to fall in, then we'll assess it in terms of our capacity to cope.
"At this stage, it's a fairly fast-moving front. We've got the A&P Show on here tomorrow... we've got Hokitika Driftwood and Sand...
"Everyone will probably be able to go about their business by mid-morning tomorrow in sunshine - that's the bizarre part of it all.
"Tourists don't know the coast and how it rains and its capacity for rainfall, so they look at it and go, 'Oh god, that's going to be wet - I'm not going there'. And it may not even happen.
"Some of these fronts are very fast-moving and we'll get them at night time... with very heavy rain and deluges, and the next day you've got a stunning, sunny, fine day, but people don't know that... So the [rain warnings] have a significant impact. There's a downside to all."
West Coast Regional Council chief executive Darryl Lew said 95 percent of the Waiho (Waihau) River's main channel was now flowing into the Tatare Stream.
The Waiho Technical Advisory Group had been preparing for this to happen, he said.
WCRC councillors, Westland District Council, Department of Conservation, NZTA and community leaders will be attending a briefing at 1.30pm this afternoon.
"We would like to assure the community that Council is monitoring the river flow and will be providing an update on the next steps on Friday afternoon," Lew said.
MetService meteorologist Mmathapelo Makgabutlane said people in Westland should prepare for intense rain overnight.
"The rain event we had last week brought quite a lot of rain up in the ranges and that has all fed into the rivers, and as we saw mid-week we had some more heavy rain out there, so river levels are maybe running a bit higher than they were about two weeks ago," she said.
"This rain we're expecting in the overnight period will be bringing extra rain on top of that so we are just keeping an eye on that. If people are in that area it might be a good idea to see what your plans are for the overnight period and make sure you are in a safe place."
Makgabutlane said the rain was expected to ease off Saturday morning.
Tasman residents, meanwhile, should expect 70-90mm of rain; while Buller should expect 75-100mm, especially about the ranges.
RNZ
