New Zealand: Heavy rainfall and strong winds forecast in northern North Island through at least early June 8 /update 1

Event

Thunderstorms, heavy rainfall, and strong winds are forecast to impact portions of northern North Island through at least early June 8. The affected areas include Auckland, Northland, and northern Waikato regions. As of June 7, the New Zealand National Meteorological Service (MetService) has issued the following warnings:

• Heavy Rain Warning: Coromandel Peninsula and Northland; 5-8 cm (2-3 inches) of rainfall could occur in these areas.

• Strong Wind Warning: Northland.

• Heavy Rain Watch: Auckland from Albany northwards, including Great Barrier Island.

• Strong Wind Watch: Coromandel Peninsula and Auckland from the Harbour Bridge northwards, including Great Barrier Island.

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

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 a 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 some delays and cancellations at regional airports. Authorities may temporarily suspend port operations along the Tasman Sea and South Pacific Ocean 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 that see 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