11 Apr 2023 | 03:54 AM UTC
New Zealand: Adverse weather forecast over scattered parts of the country through at least April 12 /update 3
Severe weather forecast over scattered parts of New Zealand through April 12. Flooding and associated disruptions possible.
Event
Severe weather is forecast over scattered parts of the country through at least April 12. As of the afternoon of April 11, the Meteorological Service of New Zealand (MetService) has issued the following watches and warnings:
Orange Heavy Rain Warning (the middle level on a three-tier scale): Westland about and north of Mount Cook. A further 16-22 cm (6-9 inches) is forecast around the ranges of Westland.
Yellow Heavy Rain Watch: Buller, headwaters of the Canterbury lakes and rivers between Lewis Pass and Mount Cook, Dunedin, and North Otago.
Yellow Severe Thunderstorm Watch: Auckland, Bay of Plenty, Coromandel Peninsula, Great Barrier Island, Northland, Rotorua, Taumarunui, Taupo, Taranaki, Waikato, and Waitomo.
Authorities will likely issue new alerts or update/rescind existing advisories as weather conditions change over the coming days.
Four tornadoes impacted New Zealand over the recent days; one in Auckland late April 9, one in the Tasman Region the afternoon of April 10, and one in Waitara, Taranaki Region, and another in the Kapiti Coast District early April 11. The tornado in the Kapiti Coast District resulted in at least 20 damaged structures in Paraparaumu and one person injured. Reports indicate that power lines are down in the area.
The previous tornado in East Tamaki and Flat Bush in Auckland late April 9 damaged at least 51 houses, while the tornado in rural Tasman the afternoon of April 10 damaged more than 70 structures. Damage assessments are ongoing; the full impact of the storms is likely to be known 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. Additional 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.
