21 Sep 2023 | 02:57 AM UTC
New Zealand: Heavy rainfall, snowfall, and strong winds forecast across most of the country through at least Sept. 23 /update 1
Heavy rainfall, snowfall, and strong winds forecast across most of New Zealand through Sept. 23. Disruptions likely.
Event
Heavy rainfall, snowfall, and strong winds are forecast across most of the country through at least Sept. 23. The New Zealand National Meteorological Service (MetService) has issued the following weather warnings as of Sept. 21:
Orange (middle level on a three-tier scale) Heavy Rain Warning: Bryant and northern Richmond ranges, headwaters of the Canterbury lakes and rivers south of Arthur's Pass, headwaters of the Otago lakes and rivers, Clutha, Fiordland, Southland, Tasman west of Motueka, and Westland south of Otira. The heaviest rainfall of up to 35 cm (14 inches) is forecast about the ranges of Westland. Thunderstorms are possible.
Orange Heavy Snow Warning: Inland Canterbury and Mackenzie Country. The heaviest snowfall of up to 40 cm (16 inches) is forecast about the Mackenzie Basin.
Orange Strong Wind Warning: Canterbury High Country and Otago.
Yellow Heavy Rain Watch: Buller, Otago excluding Clutha and the headwaters, Taranaki Maunga/Mount Taranaki, Tararua Range, Westland and north of Otira.
Yellow Heavy Snow Watch: Central Otago and Queenstown Lakes.
Yellow Strong Wind Watch: Canterbury Plains and Christchurch, including the Banks Peninsula.
Road Snowfall Warning: Lindis Pass (SH8), Arthur's Pass (SH73), Porters Pass (SH73), and Crown Range Road.
Authorities will likely issue new alerts or update/rescind existing advisories as weather conditions change over the coming days.
Strong winds prompted flight delays and cancellations at Dunedin International Airport (DUD) Sept. 20. Another flight from Wellington had to return after it was unable to land. Dense fog caused domestic flight delays and cancellations at Auckland Airport (AKL) Sept. 21. International and domestic flights to Wellington, Christchurch, Dunedin, and Queenstown remain unaffected. Authorities have suspended some ferry services connecting downtown Auckland to Waiheke Island and Half Moon Bay. Parts of several highways are closed due to damage, landslides, and the risk of avalanches, including SH1 between Kitchen and Makene roads through the Mangamuka Gorge, SH 6 between Haast and Makarora, the Mount Pisa Road intersection, SH25A between Kopu and Hikuai, and SH 94 between East Gate (Hollyford) and Westgate (Donne River).
Where precipitation falls as rain, flash and areal flooding is possible. This may occur in low-lying communities near watercourses and other large bodies of water, as well as in urban areas with easily overwhelmed stormwater drainage systems. Sites located downstream of large reservoirs may be subject to flash flooding after relatively short periods of intense rainfall.
Precipitation could fall as snow in the higher elevations over the coming days. Wind gusts could cause blowing and drifting snow; decreased visibility is likely in mountainous areas. Rain-induced landslides are possible in areas of elevated terrain; there is also the possibility of avalanches in mountainous areas where the snowpack has become unstable due to heavy snowfall. Power outages are likely throughout the affected area.
Floodwaters and related debris are likely to render some bridges, rail networks, or roadways impassable, impacting overland travel in and around the affected area. Flooding in urban areas will likely cause significant traffic congestion. Heavy snow will make driving hazardous in some areas; authorities will likely implement temporary road closures or detours in such locations. Mountain passes and tunnels could be closed as a precautionary measure during periods of intense snowfall.
The disruptive weather will likely cause additional delays and cancellations at airports across the affected region. Authorities will probably temporarily suspend port operations if strong winds trigger hazardous sea conditions, impacting freight and passenger maritime traffic. Flooding/snow could block regional rail lines, causing freight and passenger train delays and cancellations.
Disruptions triggered by inclement weather and resultant hazards, such as flooding or avalanches, will likely persist well after conditions have improved - it could take days before any floodwaters recede and/or officials clear debris. Repair or reconstruction efforts may result in residual disruptions if there is severe damage to infrastructure.
Advice
Monitor local media for weather-related updates and advisories. Seek updated information on road conditions before driving or routing shipments through areas where severe weather is forecast; plan for possible delivery delays throughout the affected area. Allow extra time to reach destinations and carry an emergency kit and warm clothes if driving is necessary, especially on secondary or rural routes that could become impassable. Charge battery-powered devices in the case of prolonged electricity outages.
