New Zealand: Adverse weather forecast over parts of North Island through at least Jan. 31 /update 2

Event

Heavy rainfall accompanied by severe thunderstorms and strong winds are impacting parts of North Island as of morning Jan. 29 and further severe weather is forecast through at least Jan. 31 across much of North Island and far northern South Island. The severe weather is causing widespread disruption across Auckland and other surrounding areas. A subtropical low in the northwest of northern North Island is likely to remain through Jan. 31 bringing heavy rain before moving southwards towards Tasman Sea Feb. 1-3.

Heavy downpours could trigger flooding in low-lying areas and landslides on unstable slopes and strong winds could cause property damage and power outages.

As of morning Jan. 29, the New Zealand National Meteorological Service (MetService) has issued the following weather warnings:

• Orange Heavy Rain Warnings (the second-highest level on a three-tier scale): The Coromandel Peninsula, Northland

• Yellow Severe Thunderstorm Watches: Auckland, Northland, Manawatu, Kapiti-Horowhenua, Tararua, Wairarapa

• Yellow Heavy Rain Watch: Auckland, including Great Barrier Island, Mount Taranaki, Waikato, Waitomo, Bryant and Richmond ranges, Marlborough Sounds, and the Rai Valley area

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

Authorities in Auckland have reported at least three fatalities after heavy rainfall triggered widespread flooding in and around the city from Jan. 27. Flood waters have inundated homes, shops, and other buildings in the area. Officials in North Island have declared a state of emergency. The international terminal at Auckland Airport (AKL) closed late Jan. 27 due to flooding impacting the terminal building and surrounding road; the facility has since reopened. Officials are warnings of disruptions due to backlog. Many roads across Auckland and its environs have been made impassable by flooding and landslides, including sections of State Highway 1. Further severe weather is forecast over the coming days, and additional heavy downpours will likely exacerbate the flood situation and hamper ongoing response and recovery efforts.

Hazardous Conditions
Further sustained heavy rainfall could trigger additional 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