18 Jul 2022 | 05:16 AM UTC
New Zealand: Heavy rainfall and strong winds forecast in parts of southern and central regions through at least July 19
Heavy rainfall, strong winds forecast in parts of southern and central New Zealand through July 19. Flash flooding, disruptions possible.
Event
Heavy rainfall and strong winds are forecast in southern and central New Zealand through at least July 19. A front is forecast to approach the South Island from the Tasman Sea July 18 before tracking northeast over the island late July 18-19. The front is likely to bring significant heavy rain to the western and central parts of the South Island and severe gales to parts of the South Island as well as Wellington and southern Wairarapa in the North Island.
As of the afternoon of July 18, the New Zealand National Meteorological Service (MetService) has issued the following warnings:
Orange Heavy Rain Warning (middle level on a three-tier scale): Fiordland, the headwaters of the Canterbury lakes and rivers about and south of Arthur's Pass, the headwaters of Otago lakes and rivers, and Westland south of Otira; further 11-30 cm (4-12 inches) of rain is likely to accumulate, with the heaviest rainfall likely in Westland.
Orange Strong Wind Watch: Canterbury, Fiordland, Marlborough, Otago, Southland, Stewart Island, Wairarapa south of Greytown, and Wellington.
Yellow Heavy Rain Watch: Buller south of Little Wanganui, Taranaki about and north of the mountain, and Tasman west of Motueka.
Yellow Strong Wind Watch: Westland.
Authorities will likely issue new alerts or update/rescind existing advisories as weather conditions change over the coming days. The heavy rain is likely to lead to rapid water level rises in rivers and streams. Surface flooding, landslides, and hazardous driving conditions are possible.
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 region, including but not limited to Christchurch International Airport (CHC), Wellington International Airport (WLG), and Queenstown International Airport (ZQN). 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 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.
