16 Mar 2023 | 07:57 AM UTC
New Zealand: Severe weather forecast over most of South Island and southern, central, and northeastern North Island through at least March 18 /update 1
Severe weather forecast over southern and central New Zealand through at least March 18. Flooding and associated disruptions possible.
Event
Severe weather is forecast over most of South Island and southern, central, and northeastern North Island through at least March 18. A low-pressure system is forecast to approach New Zealand from the northwest March 16 before crossing the country March 17-18. As of March 16, the Meteorological Service of New Zealand (MetService) has issued the following watches and warnings:
Orange Heavy Rain Warnings (the middle level on a three-tier scale): the headwaters of Canterbury lakes and rivers about and south of Arthurs Pass, Fiordland north of Dusky Sound, Mount Taranaki, Tararua Range, ranges of Tasman west of Motueka, and Westland. Heaviest rainfall of 30 cm (12 inches) is likely in the ranges of Westland.
Orange Strong Wind Warnings: Canterbury High Country, Marlborough, and Wellington.
Yellow Heavy Rain Watches: Bay of Plenty ranges east of Opotiki, Buller, Clutha, Fiordland about and south of Dusky Sound, Marlborough Sounds, central plateau of the North Island from Tongariro National Park to the Kaimanawa Range, central Otago, headwaters of the Otago lakes and rivers, Queenstown Lakes District away from the Otago headwaters, Richmond and Bryant ranges including the Rai Valley area, and Southland.
Yellow Strong Wind Watches: Banks Peninsula, Buller, south Taranaki, Wairarapa south of Masterton, Westland, and Whanganui.
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 are possible in areas impacted by the weather system.
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 additional delays and cancellations at regional airports. Flooding could block regional rail lines; freight cancellations are possible in areas subject to heavy rainfall and track blockages.
Disruptions triggered by inclement weather and resultant hazards, such as flooding, could persist well after weather 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 or reported. Do not drive on flooded roads. Charge battery-powered devices in the case of prolonged electricity outages.
