13 May 2022 | 11:09 AM UTC
New Zealand: Heavy rainfall forecast over western South Island and southern North Island through at least May 15
Heavy rainfall forecast over western South Island and southern North Island, New Zealand, through May 15. Flooding and disruptions possible.
Event
Heavy rainfall is forecast in portions of western South Island and southern North Island through at least May 15. A weather front will move northwards from southwestern South Island early May 14 along the western coast and ranges and onto the southern North Island late May 14-early May 15. The New Zealand National Meteorological Service (MetService) has warned of a low risk of the rainfall being accompanied by thunderstorms across southern parts of western South Island early May 14 and a moderate risk for northern parts of western South Island late May 14.
As of late May 13, the MetService has issued the following weather warnings across the affected region:
Orange (middle level on a three-tier scale) Heavy Rain Warning: Fiordland. Rainfall totals of 7-10 cm (3-4 inches) are expected early May 14.
Heavy Rain Watch: The ranges of both Buller and Westland north of Otira; the ranges of Westland south of Otira; and the Tararua Range.
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 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 some delays and cancellations at airports in the affected regions. 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.
