New Zealand: Severe weather forecast across much of the country through at least April 12 /update 1

Severe weather is forecast across much of New Zealand through at least April 12. A front is moving slowly between Westland and Fiordland April 10 and is forecast to move northward over northern South Island April 11 and over North Island April 12. Heavy rainfall and associated disruptions are ongoing in western parts of South Island as of April 10 and further showers, storms, and strong winds are expected to spread over other parts of the country as the system moves northward. Rough seas are expected along the western coast of South Island. Some residents in Franz Josef in Westland District were evacuated as a precaution due to rising river levels overnight April 9-10 and power outages have been reported in areas around the town of Haast. Sections of the SH6 highway between Franz Josef and Haast are closed due to landslides and the further severe weather forecast.

As of April 10, the New Zealand National Meteorological Service (MetService) has issued the following weather warnings:

• Orange Heavy Rain Warning (middle level on a three-tier scale): Mount Taranaki; Tasman northwest of Motueka; Westland District south of Hokitika; Headwaters of Canterbury Lakes and Rivers south of Arthur's Pass; Headwaters of the Otago Lakes and Rivers; Fiordland; Southland; the Bryant Range and inland Marlborough west of Blenheim and north of the Awatere River; and Buller District south of Seddonville and northwest of Reefton.

• Yellow Heavy Rain Watch: Northland; Nelson Lakes, Buller District about and southeast of Reefton, Grey District, and Westland District about and north of Hokitika; and Clutha.

• Yellow Strong Wind Watch: Taranaki south of the Mountain, Taihape, and the Whanganui Hill Country; Buller District, Nelson/Tasman and Marlborough; Wellington; and Canterbury High Country.

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

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 rain 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 or landslides impact utility networks.

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. Authorities may temporarily suspend port operations or close beach fronts along the east coast if strong winds trigger hazardous sea conditions. Flooding could block regional rail lines; freight and passenger train delays and cancellations are likely in areas with heavy rainfall and potential track inundation.

Localized business disruptions are likely 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.