19 Apr 2023 | 12:36 AM UTC
New Zealand: Adverse weather forecast over parts of northwestern South Island and southern North Island through at least early April 22 /update 1
Severe weather forecast over parts of central New Zealand through early April 22. Flooding and associated disruptions possible.
Event
Severe weather is forecast over parts of northwestern South Island and southern North Island through at least early April 22. A front over the northern South Island is tracking slowly northwards, bringing heavy rain to parts of central New Zealand, and is likely to weaken late April 19. All associated warnings and watches are likely to be lifted early April 20. A low-pressure system over the Tasman Sea is forecast to approach the northern South Island late April 19-20, bringing heavy rain to Buller, Nelson, and Westland.
As of April 19, 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): Kapiti Coast and Tararua Range. 10-15 cm (4-6 inches) of rainfall is forecast about the Tararua Range and 7-10 cm (3-4 inches) about the Kapiti Coast.
Yellow Heavy Rain Watch: Buller, Mount Taranaki, Nelson northwest of Motueka, Wairarapa south of Greytown, Wellington, and Westland.
Authorities will likely issue new alerts or update/rescind existing advisories as weather conditions change over the coming days.
Reports indicate that widespread flooding is ongoing across Wellington; authorities have advised residents to stay home and avoid unnecessary travel. Hazardous travel conditions are likely.
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 airports across the affected region. 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.
