10 Jun 2022 | 02:06 AM UTC
New Zealand: Adverse weather forecast over South Island and southern North Island through at least June 11 /update 3
Adverse weather forecast over South Island and southern North Island, New Zealand, through June 11. Flooding and disruptions possible.
Event
A series of weather fronts are forecast to bring heavy rainfall, thunderstorms, and strong winds to South Island and southern North Island through at least June 11. Thunderstorms may be accompanied by strong wind gusts, hail, and possible small tornadoes. Snowfall is also possible over areas of higher elevation in western South Island, and rough seas are forecast for parts of southern North Island.
As of June 10, the New Zealand National Meteorological Service (MetService) has issued the following weather warnings across the affected region:
Orange (middle level on a three-tier scale) Heavy Snow Warning: Fiordland. Heavy snow accumulations of 20-30 cm (8-12 inches) are possible in areas above 400 meters (1,312 feet).
Orange Strong Wind Warning: Marlborough Sounds, Wairarapa about and south of Featherston, and Wellington.
Yellow Heavy Rain Watch: Buller, Nelson Lakes, and Westland.
Yellow Severe Thunderstorm Watch: Buller, Canterbury High Country, Fiordland, Nelson, Southern Lakes, and Westland.
Yellow Heavy Snow Watch: Clutha, central Otago, the Queenstown Lakes District, Southland, and the Canterbury High Country west of Otematata and about and south of Mount Cook village.
Yellow Strong Wind Watch: Buller, Marlborough excluding the Sounds, Canterbury High Country, central Otago, Queenstown Lakes District, Southland, Clutha, Dunedin, North Otago, Canterbury Plains including Christchurch and Banks Peninsula, Wairarapa north of Featherston, the Tararua District, the ranges of Hawke's Bay about and south of Te Haroto, Taihape, and Westland.
Road Snowfall Warning: Lewis Pass (SH7), Arthur's Pass (SH73), Porters Pass (SH73), Haast Pass (SH6), Lindis Pass (SH8), Milford Road (SH94), Dunedin to Waitati Highway (SH1), and Crown Range Road.
Heavy Swell Warning: Kapiti-Porirua Coast from Otaki to Cape Terawhiti.
Authorities will likely issue new alerts or update/rescind existing advisories as weather conditions change over the coming days.
Authorities reported major power outages in Wellington City early June 9; services have since been restored. A lightning strike in Buller District early June 10 resulted in power outages affecting 4,788 people; service was quickly restored.
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 airports in the affected regions. 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. Review contingency plans and be prepared to move quickly to shelter if tornado warnings are issued. Charge battery-powered devices in the case of prolonged electricity outages.
