New Zealand: Severe weather forecast across northern and northeastern regions through at least May 23 /update 1

Severe weather is forecast across northern, western, and eastern North Island and far northeastern South Island through at least May 23. As of early May 21, the New Zealand National Meteorological Service (MetService) has issued the following weather warnings:

• Orange Heavy Rain Warning (middle level on a three-tier scale): Hawke's Bay, Tararua District, and Wairarapa. Rainfall of up to 20 cm (8 inches) is forecast. Further rain is forecast May 24; authorities have advised that the warning may be extended.

• Yellow Heavy Rain Watch: Kaikoura ranges and Tairawhiti/Gisborne.

• Yellow Strong Wind Watch: Horowhenua Kapiti Coast, North Taranaki, and Wellington

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

Authorities have evacuated residents of Western Road in Ngongotaha, near Lake Rotorua, as a precaution. Heavy rainfall flooded 70 houses in east and south Auckland. Numerous roads are closed due to flooding, landslides, and damage, including SH1 between Kitchen and Makene roads through the Mangamuka Gorge and SH 35 from Tokomaru Bay to Te Puia Springs.

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 probably cause hazardous driving conditions on regional highways. Authorities will likely close some low-lying routes that become inundated by floodwaters temporarily. 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.