24 Aug 2022 | 02:21 AM UTC
New Zealand: Further adverse weather forecast over multiple areas across the country through at least Aug. 26 /update 1
Further severe weather forecast over multiple areas across New Zealand, through at least Aug. 26. Flooding, evacuations possible.
Event
Adverse weather is forecast over multiple areas across New Zealand through at least Aug. 26. A front is forecast to track northwards and gradually weaken over South Island Aug. 24. A low-pressure system over the Tasman Sea is then likely to approach central New Zealand and track eastwards over North Island and northern South Island from Aug. 25 through early Aug. 26.
As of the afternoon of Aug. 24, the New Zealand National Meteorological Service (MetService) has issued the following weather warnings:
Orange Heavy Rain Warning (middle level on a three-tier scale): Westland south of Otira; 6-9 cm (2-3.5 inches) of rainfall is forecast, especially about the ranges.
Yellow Heavy Rain Watch: Auckland, Bay of Plenty, ranges of northern Gisborne, Mount Taranaki, Northland, and Tasman west of Motueka.
Yellow Strong Wind Watch: Auckland, Great Barrier Island, Canterbury High Country, Northland, Tararua District, Wairarapa, and Wellington.
Road Snowfall Warnings: Arthur's Pass (SH73), Porters Pass (SH73), Lindis Pass (SH8), and Crown Range Road.
Authorities will likely issue new alerts or update/rescind existing advisories as weather conditions change over the coming days.
As of the afternoon of Aug. 24, authorities are maintaining the local states of emergency across Marlborough and Nelson Tasman regions through at least Aug. 31 due to heavy rainfall and flooding since Aug. 17. Nelson City was the worst hit, with 1,200 people from 411 households displaced. More than 570 homes in the Nelson Tasman Region have been impacted by heavy rain and flooding.
Due to significant damage, State Highway 6 between Nelson and Blenheim and State Highway 63 through the Wairau Valley are likely to remain closed through at least Aug. 29 as damage assessment works are ongoing. Authorities partially reopened State Highway 6 in Nelson to northbound traffic early Aug. 24, though only during daylight hours and with speed restrictions in place. Additional rainfall is likely to exacerbate the situation and hamper recovery and relief efforts.
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.
