26 Jul 2022 | 03:43 AM UTC
New Zealand: Adverse weather forecast for most of South Island and western North Island through at least July 27 /update 1
Severe weather forecast across most of South Island and western North Island, New Zealand, through July 27. Disruptions ongoing.
Event
Heavy rainfall and snowfall over high elevations are forecast across most of South Island and western North Island through at least July 27. As of early July 26, the New Zealand National Meteorological Service (MetService) has issued the following weather warnings:
Orange Heavy Rain Warning (the middle level on a three-tier scale): Canterbury south of the Rakaia River, Dunedin, north Otago, and Tasman about and west of Motueka.
Yellow Heavy Rain Watch: Canterbury from the Rakaia River northwards, Clutha, Marlborough, Mount Ruapehu, and Mount Taranaki.
Road Snowfall Warning: Lindis Pass (SH8), Porters Pass (SH73), and Crown Range Road.
Authorities will likely issue new alerts or update/rescind existing advisories as weather conditions change over the coming days.
State Highway 63, between the State Highway 6 and Anglesea Street intersections, as well as State Highway 1 at Seddon, north of the intersection with Fearon Street, are closed due to flooding. Multiple local roads across the affected area are closed due to flooding and landslides. The Avon River in Christchurch has overflowed along Oxford Terrace near Barbadoes Street. Authorities are urging residents near the Port Hills to be vigilant for rapidly rising streams and rivers, with surface flooding and landslides.
The flood protection stopbank along the Opihi River near Pleasant Point was damaged late July 20, prompting authorities to declare a state of emergency. Authorities have since carried out emergency repairs and a river diversion but the area remains vulnerable.
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 delays and cancellations at regional airports, including but not limited to Auckland Airport (AKL). 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 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.
