05 Jan 2023 | 01:11 PM UTC
New Zealand: Adverse weather forecast over northern and southwestern North Island and far northwestern and western South Island through at least Jan. 5 /update 1
Heavy rainfall forecast across parts of northern and western New Zealand, through Jan. 6. Disruptions ongoing across Coromandel Peninsula.
Event
Heavy rainfall is forecast across northern and southwestern parts of North Island and far northwestern and western parts of South Island through at least Jan. 6. A further 7-15 cm (3-6 inches) of rainfall is forecast on top of heavy downpours that have already occurred in some areas in recent days. The heavy rain could cause landslides, surface flooding, and damage to roads.
Disruptions are ongoing across the Coromandel Peninsula as of Jan. 5 after heavy rainfall triggered severe flooding and landslides. Several roads in the area, including a section of State Highway 25, have been closed and communities around Whitianga, Kuaotunu, and Matarangi have become isolated. Further heavy rainfall is forecast in the area Jan. 6 and will likely hamper ongoing recovery efforts, as well as trigger additional flooding.
As of late Jan. 5, the New Zealand National Meteorological Service (MetService) has issued the following weather warnings:
Orange (middle level on a three-tier scale) Heavy Rain Warning: Coromandel Peninsula; Bay of Plenty west of Matata and north of Rotorua; Tasman west of Motueka; and the ranges of Westland south of Otira.
Yellow Heavy Rain Watch: Auckland including Great Barrier Island; Northern Taranaki west of Matau; and the Richmond and Bryant ranges, including the Rai Valley, as well as the Marlborough Sounds.
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 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.
