New Zealand: Severe weather forecast across parts of western South Island and far southern North Island through at least Dec. 17

Severe weather is forecast across parts of western South Island and far southern North Island through at least Dec. 17. A front is forecast to move northwards over the South Island Dec. 15, then become slow-moving over the northwest of the South Island Dec. 16-17.

As of Dec. 15, the New Zealand National Meteorological Service (MetService) has issued the following weather warnings:

• Orange Heavy Rain Warning (middle level on a three-tier scale): Buller. Periods of heavy rain and possible thunderstorms are forecast. Rainfall of 12-15 cm (5-6 inches) is likely.

• Heavy Rain Watch: Fiordland from Doubtful Sound northwards, Tararua Range, Tasman west of Takaka, and ranges of Westland.

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 will likely render some bridges or roadways impassable, impacting overland travel in and around affected areas. Ponding on road surfaces will likely cause hazardous driving conditions on regional highways. Authorities are likely to temporarily close some low-lying routes that become inundated by floodwaters. Flight delays and cancellations at airports are probable.

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.