New Zealand: Severe weather forecast across southern parts of South Island through at least Oct. 4 /update 1

Severe weather is forecast across southern parts of South Island through at least Oct. 4. A slow-moving weather front is expected to bring exceptionally heavy rainfall over southeastern parts of South Island, with major impacts from flooding and associated disruptions likely in the region. Up to 15 cm (6 inches) of rainfall is possible in North Otago, Dunedin, and coastal Clutha Oct. 3-4. Strong winds are also expected in southwestern parts of South Island.

As of late Oct. 3, the New Zealand National Meteorological Service (MetService) has issued the following weather warnings across the affected area:

• Red Heavy Rain Warnings (the highest level on a three-tier scale): North Otago, Dunedin, and coastal Clutha.

• Yellow Heavy Rain Watch: Inland Clutha and Southland.

• Yellow Strong Wind Watch: Fiordland about the Fiords.

Authorities will likely issue new alerts or update/rescind existing advisories as weather conditions change over the coming days.

Authorities in Otago have advised motorists to stay off the roads due to the threat of flooding. As of late Oct. 4, several roads in the region are closed due to flooding and landslides, including sections of State Highway 87. Officials have evacuated some residents in Surrey Street in Dunedin, and residents in South Dunedin and other low-lying areas have been encouraged to self-evacuate to higher ground due to rising floodwaters. An evacuation center has been established at St Clair Golf Club for evacuated residents.

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 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 heavy rain has saturated the soil.

Authorities could issue mandatory evacuation orders for flood-prone communities over the coming hours. Where significant flooding or landslides impact utility networks, disruptions to electricity and telecommunications services are possible.

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. Severe weather could also trigger flight delays and cancellations at regional airports. Flooding could block regional rail lines; freight and passenger train delays and cancellations are possible in areas with heavy rainfall and potential track inundation.

Localized business disruptions may occur in low-lying areas; some businesses might not operate at full capacity because of flood damage to facilities, possible evacuations, and some employees' inability to reach work sites.