18 May 2023 | 03:38 AM UTC
New Zealand: Adverse weather forecast over northern parts of North Island and southeastern and western South Island through at least May 19 /update 2
Severe weather forecast over parts of North Island and South Island, New Zealand, through May 19. Flooding and disruptions possible.
Event
Severe weather is forecast over northern and western parts of North Island and southeastern and western South Island through at least May 19. A weather front will continue to move over southern parts of South Island, bringing further heavy downpours to the region. Another weather front is forecast to track over northern and central parts of North Island through May 19, bringing heavy downpours and strong winds. Flooding is possible in low-lying areas following periods of intense rainfall, as well as landslides on unstable slopes. Strong winds could cause property damage and power outages.
As of May 18, the Meteorological Service of New Zealand (MetService) has issued the following watches and warnings across the affected area:
Orange Heavy Rain Warning (the middle level on a three-tier scale): Gisborne north of Tolaga Bay, eastern Otago between Oamaru and Clutha River, Tasman west of Motueka, and Westland from around Otira southwards to Bruce Bay.
Yellow Heavy Rain Watch: Auckland including Great Barrier Island, Bay of Plenty including Rotorua, Coromandel Peninsula, Mount Taranaki, Northland, Richmond and Bryant ranges including the Rai Valley, and Westland north of Otira including the Grey District.
Yellow Strong Wind Watch: Auckland including Great Barrier Island, Bay of Plenty including Rotorua, Coromandel Peninsula, Gisborne from Tolaga Bay northwards, and eastern Waikato
Authorities will likely issue new alerts or update/rescind existing advisories as weather conditions change over the coming days.
Hazardous Conditions
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 or a lack of stormwater drainage systems. Sites located 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 the soil has become saturated by heavy rainfall. Additional power outages are possible in areas impacted by the weather system.
Transport
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. The disruptive weather may cause additional delays and cancellations at regional airports. Flooding could block regional rail lines; freight cancellations are possible in areas subject to heavy rainfall and track blockages.
Disruptions triggered by inclement weather and resultant hazards, such as flooding, could persist well after weather conditions have improved; it could take days before any floodwaters recede and/or officials clear debris. If there is severe damage to infrastructure, repair or reconstruction efforts may result in residual disruptions.
Advice
Monitor local media for weather updates and related advisories. Confirm all transport reservations and business appointments before travel. Make allowances for localized travel delays and potential supply chain disruptions where flooding has been forecast or reported. Do not drive on flooded roads. Charge battery-powered devices in the case of prolonged electricity outages.
