New Zealand: Severe weather forecast across South Island and southern North Island through at least early Dec. 9 /update 2

Severe weather is forecast across parts of South Island and southern North Island through at least early Dec. 9. An intense front is forecast to track north over the South Island Dec. 8, bringing heavy rain to western South Island. Severe northwest gales are likely to affect most of South Island and the lower North Island. The heavy downpours may trigger flooding in low-lying areas and landslides on unstable slopes. Strong winds could cause property damage and power outages.

As of early Dec. 6, the New Zealand National Meteorological Service (MetService) has issued the following weather warnings across the affected area:

• Orange Heavy Rain Warning (the middle level on a three-tier scale): Westland District. Rainfall amounts of 25-31 cm (10-12 inches) are expected about the ranges and 10-15 cm (4-6 inches) nearer the coast. Freezing levels of about 3,200 meters (10,500 feet) are forecast, lowering to 1,900 meters (6,233 feet) the evening of Dec. 8.

• Orange Strong Wind Warning: Canterbury High Country, Wairarapa south of Masterton, and Wellington.

• Yellow Heavy Rain Watch: headwaters of the Canterbury lakes and rivers, headwaters of the Otago lakes and rivers, Grey and Buller districts, and Fiordland.

• Yellow Strong Wind Watch: Banks Peninsula, Canterbury plains, Fiordland, Hawke's Bay south of Hastings, Marlborough, Otago, Southland, Stewart Island, and Wairarapa from about Masterton northwards.

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 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 may temporarily close some low-lying routes that become inundated by floodwaters. Severe weather could trigger flight delays and cancellations at regional airports. Flooding may 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.