MetService is voicing grave concerns over how the worst-hit regions will cope with a 48-hour deluge teeming down on cyclone-devastated Hawke’s Bay and Gisborne.
It tonight upgraded its rain warnings for Gisborne and Coromandel to orange. An orange warning remains in place for Hawke’s Bay.
Significant accumulations of rain are expected in areas recently affected by Cyclone Gabrielle, it says.
And the timing for Auckland’s rain alert has changed. It is now predicted to start before dawn and to rain for longer.
MetService says Auckland and Great Barrier Island can expect “periods of heavy rain, with thunderstorms and downpours possible, especially from afternoon. Rainfall amounts may approach warning criteria.
“There is a moderate risk of localised severe thunderstorms producing downpours of 25mm/h-40mm/h from just before dawn through to Friday night.”
Niwa warns “converging winds could cause narrow corridors of intense rain with the possibility for some flooding” for Coromandel and Auckland tomorrow.
It says its high-resolution rainfall forecast indicates “locally heavy rain over Hawke’s Bay, Gisborne, Auckland and Coromandel on Friday afternoon and evening”.
Niwa also said that increasing wind on Friday would see wave heights grow.
It said in a tweet there are higher odds of flooding for parts of Hawke’s Bay and Gisborne because of rain runoff, onshore winds, growing wave heights and higher tides. Tomorrow is also the last day of a king tide, with the evening high tide in the area 10-11pm.
In response to increasing wind on Friday, wave heights will grow.
— NIWA Weather (@NiwaWeather) February 23, 2023
Friday is also the last day of a king tide.
Higher odds of flooding for parts of HB/Gisborne due to:
🌧️ rain runoff
🌬️ onshore winds
🌊 growing wave height
📈 higher tides
Evening high tide is 10-11pm. pic.twitter.com/OnFtF98PoK
Police today updated the number of uncontactable people in the wake of Cyclone Gabrielle.
As of 2pm, 56 people remain uncontactable. All of them are from the Hawke’s Bay and Tairāwhiti areas.
Meanwhile, a precautionary evacuation is underway for 64 homes in the Mangahauini River catchment and Tokomaru Bay township.
Tairāwhiti Civil Defence Controller Ben Green says with the rain forecast for tonight there is an immediate risk of the failure of the debris dam upstream of the township.
“The incoming rain amplifies the risk given the ground is very unstable and saturated following the damage done by Cyclone Gabrielle,” Green said.
“The community is being evacuated to local marae or to stay with whanau in areas outside of the Mangahauini River catchment.
“Our Civil Defence team on the ground in Tokomaru Bay went door to door this afternoon. The safety of our people is paramount.”
Our high-res rainfall forecast indicates locally heavy rain (🟣) over Hawke's Bay, Gisborne, Auckland & Coromandel on Friday afternoon & evening...
— NIWA Weather (@NiwaWeather) February 23, 2023
For Auckland & Coromandel, converging winds could cause narrow corridors of intense rain with the possibility for some flooding. pic.twitter.com/h1gxVFxCWt
An orange heavy rain warning is in force for Hawke’s Bay and heavy rain watches for Auckland, Gisborne, Wairarapa, Coromandel and Bay of Plenty.
“MetService is concerned for vulnerable areas like Esk Valley and the Wairoa District, given that 150 to 200mm in those areas could have significant impacts given slash and silt through the area,” said meteorologist Amy Rossiter.
She said the forecaster said it held grave concerns for impacts given the already vulnerable terrain.
There is also a risk of thunderstorms for much of the upper North Island today and tomorrow, with the potential that some of these thunderstorms could be severe.
MetService has issued severe thunderstorm watches this afternoon for Auckland, the Coromandel Peninsula, Hauraki Plains and Bay of Plenty from Te Puke westwards.
It warns downpours associated with the electrical storms could cause flash flooding and slips.
”People in these areas are advised to prepare as best they can in case of a downpour, although localised 40mm in an hour is a large amount of rain,” said Rossiter.
The flood-hit region’s Civil Defence today warned people to be prepared to evacuate and be wary of rivers and places where stopbanks had been damaged by the cyclone.
It comes as a fresh cyclone threat is looming in the Pacific that forecasters are keeping a close watch on.
Niwa meteorologist Ben Noll said while it was still early days to talk about any potential impact on New Zealand there was a heightened risk of a cyclone forming next week.
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“We have been watching this potential for this feature since Gabrielle came down,” said Noll. “What we’re seeing in the first 10 days of March is an increased risk for cyclone formation.
“That’s definitely something for Kiwis, especially those in the North Island, to keep a very close eye on the forecast. It’s not imminent or immediate but it may be something we’re going to have to face in the first 10 days of March.”
Meanwhile, a swathe of Auckland’s West Coast beaches are shut to the public this weekend, with roads to popular seaside destinations compromised amid warnings that heavy rain could re-activate slips.
Access to Karekare, Piha, Te Henga-Bethells Beach, Muriwai, Anawhata, Huia, Little Huia and Whatipu had been compromised by Cyclone Gabrielle, said Auckland Transport chief engineer Murray Burt.
He asked the general public to stay away from these areas and limit any additional pressure on the communities by trying to visit them at this time. Burt said at the request of Piha community Piha Rd would be closed this weekend to everyone except residents and emergency services, from midday on Friday.
“A cordon will be set up. Repairs have started on Bethells Rd, we ask non-residents to stay away while the repairs are underway so we can minimise as much traffic on the road as possible.
“From today the main works at Bethells Beach have begun, which means only pedestrian access for residents will be permitted. This will be in place for seven days while we work to reopen full access to Bethells Beach Rd.”
Burt said work was also underway to rebuild a section of Glenvar Rd in the North Shore, however the extent of damage meant that would take some time, maybe months.
About 30 roads remain closed across the Auckland region due to the impact of the storm.
Burt said he visited the site of a slip at Elevation on Scenic Drive in Piha where he heard first-hand people’s struggle to access the area.
“Please be reassured [the] Elevation slip is a top priority and geo-tech assessment is being taken by our contractors GHD.
“I hope to have good news about being able to reopen single-lane access through this area shortly.
“We will continue to work closely with the communities and listen to their concerns.”
Auckland Emergency Management duty controller Rachel Kelleher said the key message was to keep an eye on the forecast and note the heavy rain watch in place for tomorrow.
She also warned of the possibility of the reactivation of slips.
”Stay vigilant,” she warned.
The beach ban comes as much of the storm-ravaged North Island sits under a raft of heavy rain and severe thunderstorm watches and warnings, for the coming two days.
They allege the Crown ignored Treaty obligations by not engaging with them.