New Zealand: Adverse weather forecast across North Island and northern South Island through at least Feb. 14 /update 1

Event

Heavy rainfall and strong winds are forecast across North Island and northern South Island through at least Feb. 14. Sub-tropical Cyclone Gabrielle is forecast to make a close approach to upper North Island Feb. 13-14. Impacts from Gabrielle are already being felt across northern parts of the North Island and are likely to spread south to the rest of the North Island and northern South Island Feb. 13-14. 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, Gisborne, Hawke's Bay, 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. The strongest wind is likely in Auckland, the Coromandel Peninsula, Northland, and Taranaki; widespread damage is likely, especially to trees and powerlines. Major power outages are ongoing in parts of northern North Island.

As of the afternoon of Feb. 13, 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, Hawke's Bay, and Northland. Up to 35 cm (14 inches) of rain is forecast.

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

• Orange Heavy Rain Warning: Bay of Plenty west of Whakatane, eastern Marlborough south of Blenheim including Kaikoura Coast, Mount Taranaki, Waikato, 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, Canterbury Plains north Christchurch, Taranaki north of the mountain, Taumarunui, Taupo away from the eastern ranges, and Waitomo.

• Yellow Strong Wind Watch: Westland north of Fox Glacier.

Authorities will likely issue new alerts or update/rescind existing advisories as weather conditions change over the coming days. Authorities have warned that coastal flooding and erosion are likely for areas along the Coromandel and Bay of Plenty due to a record storm surge. As of the afternoon of Feb. 13, authorities have declared states of emergency in Auckland, Northland, Thames-Coromandel, Tairawhiti, and Opotiki. Heavy rainfall and flooding in Auckland since Jan. 27 resulted multiple fatalities. Further severe weather is likely to result in additional disruptions and hamper recovery efforts.

Authorities have urged residents close to the rivers in low-lying parts of Whangarei Central and the town basin area to evacuate due to the high risk of tidal flooding while residents in Opotiki town in low-lying areas are advised to consider evacuation if possible.

Auckland Airport (AKL) has stated that 301 domestic flights are canceled Feb. 13, while 85 out of 104 international flights have remained grounded. Air New Zealand (NZ) has stated that over 500 flights were canceled Feb. 12-14, including all flights at Auckland, Hamilton, Tauranga, and Taupo through early Feb. 14 and all flights to and from Australia and Pacific Island Feb. 13. More than 29,000 customers are affected; domestic and international jet operations are scheduled to resume mid-morning Feb. 14 and turboprop operations mid-afternoon Feb. 14.

All train services in Auckland are canceled through at least midday Feb. 14. Bus services are running but disruptions are possible. Almost 13,000 homes and businesses in Auckland and thousands of others in Northland are without power. Interislander services across the Cook Strait are canceled from 02:00 Feb. 14 while the Picton Port is also closed through at least 22:00 Feb. 14 due to high wind and swell conditions.

Multiple state highways across North Island are closed due to severe weather, flooding, and landslides, including SH 35 from Ruatoria to Tolaga Bay, SH 23 from Raglan to Whatawhata, SH 25A from Kopu to Hikuai, SH 25 from Kuaotunu to Whitianga and from Coromandel to Te Rerenga, SH 1 Mangamuka Gorge and from Waipu to Brynderwyn, and SH 16 from Kaukapakapa to Wellsford. More information can be found here.

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