New Zealand: Adverse weather forecast to continue over parts of North Island and northeastern South Island through at least Jan. 11 /update 1

Event

Severe weather, including heavy rainfall and strong winds, is forecast to continue across North Island and into northeastern South Island through at least Jan. 11 as former tropical cyclone Hale moves across the north of North Island overnight Jan. 10-11. Rainfall totals of up to 12 cm (5 inches) are possible across parts of the affected area as well as strong southeasterly winds. The storm system is expected to move away from eastern parts of North Island into the South Pacific Ocean late Jan. 11. Heavy downpours could cause landslides, flooding, and damage to roads, especially in areas where the ground is already saturated by previous rainfall over recent days.

As of late Jan. 10, the New Zealand MetService has issued the following weather warnings across the affected areas:

• Orange (middle level on a three-tier scale) Heavy Rain Warning: Coromandel Peninsula; Gisborne; Hawke's Bay; Eastern hills and ranges of Wairarapa; and the Tararua Range

• Yellow Heavy Rain Watch: Central North Island hills and mountains, especially about and south of Tongariro National Park; Mount Taranaki; and Marlborough and Canterbury coast from Cape Campbell to Kaikoura and the Seaward Kaikoura Range.

• Yellow Strong Wind Watch: Eastern Taupo; and southern Taranaki, coastal Whanganui, Manawatu, especially near the Gorge, Horowhenua, Kapiti, and Wellington.

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

Heavy rainfall has led to some rivers reaching dangerously high levels across parts of North Island as of late Jan. 10. A local state of emergency has been declared by Tairawhiti Civil Defence due to rising levels along the Hikuwai River in Gisborne District. Residents in low-lying areas near the river have been urged to prepare to evacuate and some have already self-evacuated. Flooding has also been reported in the Coromandel Peninsula and parts of Northland Region, with residents in some coastal areas warned to stay indoors during high tide due to potential coastal flooding. Around 400 residents in Matawai, Gisborne Region, and around 900 households in the Coromandel Peninsula remain without power as of late Jan. 10. Several roads across North island remain closed as of late Jan. 10 due to landslides and other weather-related factors, including sections of State Highway 1, 25A, and 35.

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. Authorities may temporarily suspend port operations if strong winds trigger hazardous sea conditions, impacting freight and passenger maritime traffic. 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
New Zealand Transport Agency