15 Sep 2023 | 08:02 AM UTC
New Zealand: Heavy rainfall and strong winds forecast across South Island and southern North Island through at least Sept. 17 /update 1
Heavy rainfall and strong winds forecast in South Island and southern North Island, New Zealand, through Sept. 17. Disruptions likely.
Event
Heavy rainfall and strong winds are forecast across South Island and southern North Island through at least Sept. 17. As of Sept. 15, the New Zealand National Meteorological Service (MetService) has issued the following weather warnings:
Orange (middle level on a three-tier scale) Heavy Rain Warning: Buller, headwaters of the Canterbury lakes and rivers south of Arthur's Pass, Fiordland north of Doubtful Sound, headwaters of the Otago lakes and rivers, and Westland. Up to 20 cm (8 inches) of rain is forecast.
Orange Strong Wind Warning: Canterbury High Country, Marlborough, Tararua District, Wairarapa, and Wellington.
Yellow Heavy Rain Watch: Fiordland about and south of Doubtful Sound.
Yellow Strong Wind Watch: Canterbury Plains, Christchurch including Banks Peninsula, Fiordland south of Milford Sound, Horowhenua, Kapiti Coast, Otago, Southland including Stewart Island, Tasman northwest of Motueka.
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.
In addition to heavy snow, strong wind gusts will likely lead to periods of blowing and drifting snow; decreased visibility is likely in mountainous areas. Blizzard conditions are possible.
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. Heavy snow could make driving hazardous in some areas; authorities may implement temporary road closures or detours in such locations. Mountain passes and tunnels could close as a precautionary measure during periods of intense snowfall. 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 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.
