New Zealand: Severe weather forecast across western and southeastern South Island and southeastern North Island through at least Dec. 5 /update 1

Severe weather is forecast across parts of western and southeastern South Island and southeastern North Island through at least Dec. 5. A front will continue to move over central New Zealand early Dec. 4 before a second more active front moves quickly northward over southern and central New Zealand late Dec. 4-early Dec. 5. Heavy rainfall with thunderstorms is expected over western parts of South island, as well as strong winds over southeastern South Island and southeastern 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 late Dec. 3, 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): Ranges of the Westland District. Rainfall amounts of 10-14 cm (4-5.5 inches) are expected in the warning area.

• Yellow Heavy Rain Watch: Fiordland about and north of George Sound.

• Yellow Strong Wind Watch: Hawke's Bay south of Hastings and Wairarapa and Dunedin, Clutha, southern Southland, and Stewart Island.

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.