Heavy rain will likely cause surface flooding and slips, road washouts and make driving difficult while strong winds could damage trees, powerlines and unsecured structures.
That’s the warning from MetService as Cyclone Gabrielle brings severe weather to New Zealand.
It has been described as a “very significant adverse weather event”, with severe weather warnings and watches in force across the country, including heavy swell warnings.
Metservice meteorologist John Law said from Katikati to Whakatāne, including Tauranga and Rotorua, between 120 to 180mm of rain was forecast between 9am today and 3pm tomorrow.
While there was not as much rain as in other parts of the North Island, Law said the forecast was “still substantial” with peak rates expected between 10 to 15mm/h but could reach up to 30mm/h.
“There is a lot of rain to come through and it’s going to be followed by strong winds as well,” Law said.
Law described the cyclone and its effects as a “slow-moving situation” and predictions for the rest of the week were “not the driest of forecasts”.
He expected the weather to ease as the week went on, with today and tomorrow “our wettest days”.
Heavy rain could cause streams and rivers to rise rapidly, with surface flooding and slips possible.
Rainfall totals between 300 to 400mm were expected in the Coromandel Ranges and 150 to 250mm elsewhere. Peak intensities of 10 to 15mm/h were forecast but could reach 45mm/h about the ranges this afternoon and evening.
“This rain is expected to cause dangerous river conditions and significant flooding,” the forecast said. “Slips and floodwaters are likely to disrupt travel, making some roads impassable and possibly isolating communities.”
Strong southeast winds were forecast until 9am tomorrowwith severe gale gusting up to 120km/h to 130km/h and possibly higher in exposed places.
The strongest period was expected this afternoon and overnight.
The whole of the North Island was on a severe weather warning for strong wind, with it being orange in the Bay of Plenty.
Tropical Cyclone Gabrielle had been downgraded to a sub-tropical low over the weekend but MetService head of weather communication Lisa Murray said that did not mean it had weakened and was in fact intensifying across a wider area.
“Extreme rain and wind are expected for many North Island regions, accompanied by phenomenal seas along northern and eastern shores, and significant storm surge near, and slightly in advance of, the cyclone’s centre.
“The wind of this strength combined with rain means rain could be almost horizontal making it very difficult to walk in and rain could get under the eaves of houses adding to the flooding risk.
“This is a really extreme and impactful event. People could lose power or become isolated. Listen to local authorities and your local Civil Defence and know where your local evacuation centre is.”
On Saturday, Murray warned strong winds could damage trees, powerlines and unsecured structures, and that sodden grounds from recent flooding increased the likelihood of trees being uprooted.
She said heavy rain would cause surface flooding, road washouts and landslips while making hazardous road conditions.
When there was a deep low off the coast, ocean levels raised and along with five to seven-metre waves and onshore wind, coastline inundation may be enhanced, Murray said.
Rotorua Lakes Council’s Civil Defence and Emergency Management team was keeping a close eye on the situation and was working to plan and prepare for how the city responds to the cyclone.
In a statement yesterday afternoon, the council advised residents to prepare for severe weather and follow directions from Civil Defence.
“There are still unknowns about exactly how the cyclone will impact New Zealand so it is important to stay up to date with changing forecasts and to prepare and respond accordingly,” it said.
“At this stage (1pm), the cyclone is likely to cause storm surges that will significantly impact coastal communities. Coastal areas and large lakes can be impacted by storm surges, inundation (flooding), and extreme tides.”
The Department of Conservation had closed all tracks and campsites, including mountain bike tracks, in Whakarewarewa, Maunga Kakaramea (Rainbow Mountain) and Western Okataina through to Thursday morning due to the forecast.
Last week, Tauranga City Council Civil Defence duty controller Nigel McGlone said its top priority was keeping communities safe and it was ready to respond to any issues.
Waka Kotahi New Zealand Transport Agency Bay of Plenty system manager Roger Brady told people to avoid driving.
“We all saw late last month how quickly the impact of rainfall can take hold.
“The impact of Cyclone Gabrielle may be similar, therefore on the days when heavy rainfall is expected please only drive if it is essential to do so.
“Staying home keeps you safe and also helps our contractors move around the network more efficiently, speeding up response times.”
Yesterday evening, Fire and Emergency New Zealand communication centres national manager Gavin Travers said crews were responding to a slow but steady stream of calls for assistance as winds increased with fallen trees impacting properties and roofs lifting.
On Friday, Minister for Emergency Management Kieran McAnulty urged people “stay safe and don’t take any chances”.
“It’s been a really tough month with communities still badly affected from last month’s flooding, which makes some areas more vulnerable.”
McAnulty announced a $100,000 contribution from the Mayoral Relief Fund to help flood-affected communities in Thames-Coromandel.
The region had multiple slips and road closures after heavy rain on Auckland Anniversary weekend, with State Highway 25A between Kopu and Hikuai severely damaged and likely to remain closed for some time.
“This initial funding will assist impacted communities as they begin the clean-up, and we will continue to work alongside Council to ensure they are appropriately supported,” McAnulty said.
“Communities in Thames-Coromandel could face further heavy rain and high winds due to Cyclone Gabrielle. The Government stands ready to respond as required.
The fire took place around midnight and took firefighters three hours to control.