Agencies across the West Coast have spent the last several days preparing for the significant weather event currently affecting the West Coast, and across New Zealand.

The latest modelling is indicating an easing in event intensity around Westport. For the Buller River, the forecast flow range has come down to 4000 – 6000 cumecs. This is a reduction from yesterday’s forecast flow of 5000 – 7200 cumecs.

While this event is still expected to bring significant flows to the Buller River, bank overtopping from the event is not expected, with flows similar to the first February event.

The peak flows will occur tomorrow, early morning for Te Kuha and mid-morning for Westport. The Orowaiti Overflow will receive flows after 4000 cumecs. The tide is slightly higher than what was experienced during the February event. This may increase river levels in the Snodgrass area.

Te Aroha Cook, West Coast Group Controller, said that observations will give confirmation of actual flows early tomorrow morning.

“For Westport, if you experienced flooding in February, or are feeling vulnerable due to proximity to the Orowaiti, you may want to consider self-evacuation. There may also be stormwater ponding, surface flooding and stopbank seepage. Self-evacuation includes making arrangements for pets and lifting valuables.”

Further south, Civil Defence and supporting agencies are still expecting rivers to rise in Westland. Peak rain intensities are expected from late Wednesday afternoon into Thursday.

“We are watching the Hokitika River closely. We know that it is currently high and more rain is expected. Peak flows are anticipated to coincide on a falling tide.”

Observations on the Wanganui and Waiho Rivers are ongoing through the event.

“As the freezing level continues to rise we can also expect increasing snow melt which will impact our river flows, particularly as we move south through the region.”

Stock and animals should be moved from low lying rural areas, including Snodgrass.

“Plan your journeys IF you need to go, but please just stay at home.”

Strong wind warnings and watches remain in place.

Heavy Rain Warning - Red

Impact: This rain is expected to cause dangerous river conditions and significant flooding. Slips and floodwaters are likely to disrupt travel, making some roads impassable and possibly isolating communities.

Area: Buller

Period: 34hrs from 9am Wed, 17 Aug - 7pm Thu, 18 Aug

Forecast: Periods of heavy rain. Expect a further 200 to 300 mm of rain to accumulate about the ranges south of Little Wanganui on top of what has already fallen, and 100 to 200 mm elsewhere. Peak rates of 15 to 20 mm/h about the ranges today.

Area: Westland

Period: 32hrs from 9am Wed, 17 Aug - 5pm Thu, 18 Aug

Forecast: Periods of heavy rain. Expect a further 200 to 300 mm of rain to accumulate about the ranges on top of what has already fallen, especially between Bruce Bay and Otira, and 80 to 150 mm about the coast. Peak rates of 10 to 20 mm/h about the ranges. Thunderstorms possible in the south on Thursday. Note, heavy rain could ease for a time from late Wednesday morning to late Wednesday afternoon.

Ms Cook noted that more rain has been forecasted for the weekend.

“We will be keeping a close eye on this.”

You can keep up to date with the latest information by:

• following the West Coast Emergency Management Facebook page
• checking state highway conditions at https://www.journeys.nzta.govt.nz/traffic/southisland
• monitoring weather conditions at https://www.metservice.com/warnings/home

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