20 Dec 2022 | 02:27 AM UTC
New Zealand: Adverse weather forecast over most of North Island through at least Dec. 21
Heavy rainfall, thunderstorms forecast across most of North Island, New Zealand, through Dec. 21. Flooding and disruptions possible.
Event
Heavy rainfall and thunderstorms are forecast across most of North Island through at least Dec. 21. A low-pressure system is forecast to affect the central and lower North Island through early Dec. 21, bringing heavy rain and thunderstorms, with the worst affected area from Hawke's Bay south of Napier to Wairarapa north of Featherston, including the Tararua District. As of Dec. 20, the New Zealand National Meteorological Service (MetService) has issued the following weather warnings:
Red (highest level on a three-tier scale) Severe Thunderstorm Warning: South Waikato, Taupo, and Rotorua; Stratford, South Taranaki, Ruapehu, Wanganui, and New Plymouth; and Horowhenua, Kapiti Coast, and Upper Hutt City. The thunderstorms are likely to be accompanied by very heavy rain and hail. Very heavy rain can cause surface and flash flooding in streams, gullies, and urban areas as well as extremely hazardous driving conditions. Hail can cause damage to crops and may make driving conditions hazardous.
Orange Heavy Rain Warning: Hawke's Bay south of Napier, Tararua District, and Wairarapa north of Featherston. Up to 15 cm (6 inches) of rainfall is forecast.
Yellow Severe Thunderstorm Warning: Buller, Waikato, Waitomo, Taumarunui, Bay of Plenty, Rotorua, Taupo, Hawkes Bay, Taranaki, Taihape, Wanganui, Manawatu, Tararua, Kapiti-Horowhenua, Wairarapa, Wellington.
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 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 delays and cancellations at regional airports. 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 with 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.
