17 May 2022 | 09:28 AM UTC
New Zealand: Heavy rainfall and strong winds forecast over much of South Island and parts of North Island through at least May 19 /update 1
Heavy rainfall and strong winds forecast over parts of South and North Island, New Zealand, through May 19. Disruptions possible.
Event
Heavy rainfall and strong winds are forecast across portions of South Island and North Island through at least May 19. Heavy rainfall is expected along the west coast of South Island and over elevated areas of North Island May 17-18 and strong winds are likely over central and southern parts of South Island late May 18-May 19. The New Zealand National Meteorological Service (MetService) has warned of a high risk of thunderstorms with possible small tornadoes over southwestern parts of South Island May 18,
As of late May 17, the MetService has issued the following weather warnings across the affected region:
Orange (middle level on a three-tier scale) Heavy Rain Warning: Mount Taranaki and Tongariro National Park.
Heavy Rain Watch: Fiordland; Buller, Westland north of Otira; Westland about and south of Otira; and the Tararua Range.
Strong Wind Watch: Canterbury High Country; and Central Otago, Southern Lakes, Clutha, Southland, and Stewart Island.
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 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. Charge battery-powered devices in the case of prolonged electricity outages.
