New Zealand: Adverse weather forecast across North Island and northern South Island through at least Feb. 14

Event

Heavy rainfall and strong winds are forecast across North Island and northern South Island through at least Feb. 14. Sub-tropical Cyclone Gabrielle, in the north Tasman Sea, is forecast to make a close approach to the upper North Island Feb. 13-14. Impacts from Gabrielle are likely in the north Feb. 12 before spreading south to other parts of northern and central New Zealand. Significant heavy rain and potentially damaging winds are forecast across northern and central parts of the country. In addition, large waves, storm surges, and coastal inundation are possible in the exposed eastern coasts of the North Island. The heaviest rainfall is likely in Auckland, the Coromandel Peninsula, northern Gisborne, and Northland; dangerous river conditions and significant flooding are likely. Heavy downpours could trigger flooding in low-lying areas and landslides on unstable slopes and strong winds may cause property damage and power outages.

As of the afternoon of Feb. 12, the New Zealand National Meteorological Service (MetService) has issued the following weather warnings across the affected area:

• Red Heavy Rain Warnings (the highest level on a three-tier scale): Auckland, including Great Barrier Island and other islands in the Hauraki Gulf, Coromandel Peninsula, Gisborne north of Tolaga Bay, and Northland. Up to 45 cm (18 inches) of rain is forecast.

• Red Strong Wind Warnings: Auckland, including Great Barrier Island and other islands in the Hauraki Gulf, Coromandel Peninsula, and Northland.

• Orange Heavy Rain Warning: Bay of Plenty west of Whakatane, Gisborne from Tolaga Bay southwards, Hawke's Bay, eastern Marlborough south of Blenheim including Kaikoura Coast, and Wairarapa including the Tararua District.

• Orange Strong Wind Warning: most of central and southern North Island.

• Orange Heavy Swell Warning: Wairarapa from Turakirae Head to Mataikona.

• Yellow Heavy Rain Watch: Bay of Plenty from Whakatane eastwards, eastern ranges of Taupo, Mount Taranaki, and Waikato.

• Yellow Strong Wind Watch: Buller north of Seddonville, Marlborough, and Nelson.

Authorities will likely issue new alerts or update/rescind existing advisories as weather conditions change over the coming days.

Authorities in Coromandel are advising residents in at-risk areas to self-evacuate. Air New Zealand (NZ) has canceled all flights at Auckland, Hamilton, Tauranga, and Taupo through midday Feb. 14, all flights to and from Australia and Pacific Island Feb. 13, and domestic services in Auckland Feb. 13. Some long-haul flights have also been canceled. Further flight cancelations are likely as the weather system approaches. Speed and lane restrictions are in place on the Auckland Harbour Bridge early Feb. 12 due to severe wind gusts; high-sided vehicles and motorcycles are advised to delay their journey or detour via SH18/SH16 (Western Ring Route). Thousands of homes across Northland and Auckland are without power; prolonged outages are likely.

Authorities in Auckland have extended the local state of emergency through at least Feb. 17 in advance of Cyclone Gabrielle. Heavy rainfall and flooding since Jan. 27 resulted multiple fatalities. Further severe weather is likely to result in additional disruptions and hamper recovery efforts.

Hazardous Conditions
Sustained heavy rainfall could trigger flooding in low-lying communities near rivers, streams, and creeks. Urban flooding is also possible in developed areas with easily overwhelmed or lack of stormwater drainage systems. Sites located downstream from large reservoirs or rivers may be subject to flash flooding after relatively short periods of intense rainfall. Landslides are possible in hilly or mountainous areas, especially where the soil has become saturated by heavy rainfall. Power outages could occur throughout the affected area.

Transport
Floodwaters and debris flows may render some bridges, rail networks, or roadways impassable, impacting overland travel in and around affected areas. Ponding on road surfaces could cause hazardous driving conditions on regional highways. Authorities could temporarily close some low-lying routes that become inundated by floodwaters. The disruptive weather may cause delays and cancellations at regional airports. Flooding could block regional rail lines; freight cancellations are possible in areas with heavy rainfall and potential track blockages.

Disruptions triggered by inclement weather and resultant hazards, such as flooding, could persist well after conditions have improved - it could take days before any floodwaters recede and/or officials clear debris. If there is severe damage to infrastructure, repair or reconstruction efforts may result in residual disruptions.

Advice

Monitor local media for weather updates and related advisories. Confirm all transport reservations and business appointments before travel. Make allowances for localized travel delays and potential supply chain disruptions where flooding has been forecast. Do not drive on flooded roads. Charge battery-powered devices in the case of prolonged electricity outages.

Resources

New Zealand National Meteorological Service
NZ Transport Agency