New Zealand: Heavy rainfall, snowfall, and strong winds forecast across west central North Island and most of South Island through at least Aug. 20

Event

Heavy rainfall, snowfall, and strong winds are forecast across west central North Island and most of South Island through at least Aug. 20. The New Zealand National Meteorological Service (MetService) warned that a front is forecast to track across South Island Aug. 19 before moving slowly across the North Island Aug. 20, bringing heavy rain and north to northeast gales to western parts of the South Island and central North Island. As of early Aug. 18, the MetService has issued the following weather warnings:

• Orange (middle level on a three-tier scale) Heavy Rain Warning: Mount Taranaki and the ranges of Westland south of Otira. Up to 14 cm (5.5 inches) of rain is forecast.

• Orange Strong Wind Warning: Fiordland about the fiords.

• Yellow Heavy Rain Watch: Buller, central North Island hill country from eastern Taranaki to Taihape and northwards to Waitomo and Tasman about and west of Motueka.

• Yellow Strong Wind Watch: Buller, Canterbury High Country, Nelson, Tasman, and Westland.

• Road Snowfall Warning: Milford Road (SH94) and Crown Range Road

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 stormwater drainage systems. Sites 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 heavy rainfall has saturated the soil.

Authorities could issue mandatory evacuation orders for flood-prone communities over the coming days. Disruptions to electricity and telecommunications services are likely where significant flooding, landslides, or strong winds impact utility networks.

Transport
Floodwaters and debris flows will likely 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 cancelations at airports in the affected regions. Flooding could block regional rail lines; freight cancellations are possible in areas with heavy rainfall and potential track blockages.

Localized business disruptions will likely occur in areas impacted by severe weather; some businesses might not operate at full capacity because of damage to facilities, possible evacuations, and some employees' inability to reach work sites.

Advice

Monitor local media for weather-related updates and advisories. Seek updated information on road conditions before driving or routing shipments through areas where severe weather is forecast; plan for possible delivery delays throughout the affected area. Allow extra time to reach destinations and carry an emergency kit and warm clothes if driving is necessary, especially on secondary or rural routes that could become impassable. Charge battery-powered devices in the case of prolonged electricity outages.

Resources

MetService