Key Takeaways
- A vigorous thunderstorm produced roughly 6,200 lightning strikes across Nelson, Tasman, and Wellington between 6 p.m. and 6:30 a.m., with visible bolts captured by residents.
- MetService issued orange heavy‑rain warnings for parts of the Bay of Plenty and Taranaki, and numerous heavy‑rain watches spanning the central North Island, Wellington, and the Tasman region.
- The storm caused temporary power outages; Transpower reported losses shortly before 9 p.m., and Network Tasman had restored electricity by 9:45 p.m. while continuing reconnection work.
- Forecasts indicate sporadic thunderstorms and heavy showers will persist through tonight and tomorrow, with an improving trend expected by Sunday, which should be brighter with only isolated showers in the far south.
- Heavy rain overwhelmed Wellington’s short outfall pipe at Moa Point, causing untreated wastewater to discharge into Tarakena Bay and potentially travel along the coastline.
Overview of the Overnight Thunderstorm
Late Friday night, a series of lightning bolts illuminated the sky over Nelson as a thunderstorm moved through the region. MetService confirmed that approximately 6,200 lightning strikes were recorded between 6 p.m. and 6:30 a.m. across Nelson, Tasman, and Wellington. Residents shared video footage with 1News, showing vivid streaks of lightning cutting across the clouds. The electrical activity accompanied strong gusts and heavy rain, prompting the national weather service to issue several warnings for the central North Island and surrounding areas.
MetService Weather Warnings and Watches
In response to the approaching rain band from the Tasman Sea, MetService placed orange heavy‑rain warnings for specific zones: the Bay of Plenty east of Whakatāne (12 hours from 5 p.m. Friday to 5 a.m. Saturday) and Taranaki north of Eltham (21 hours from midnight Thursday to 9 p.m. Friday). Additionally, heavy‑rain watches were issued for a broad sweep of the country, including the Bay of Plenty west of Whakatāne, Taupō, Waitomo, Taumarunui, Tongariro National Park (including the Whanganui River headwaters), Horowhenua, Kapiti Coast, Wellington, the Tararua Range, Buller, and the Tasman Ranges. These alerts signaled the potential for intense rainfall, localized flooding, and thunderstorm activity.
Impact on Power Supply
The storm’s intensity disrupted electricity supply for some households. Transpower reported a power outage shortly before 9 p.m., affecting customers in the warned regions. Network Tasman responded swiftly, beginning restoration efforts almost immediately. By 9:45 p.m., power had been restored to most affected areas, though crews continued working to reconnect any remaining outages and to inspect infrastructure for storm‑related damage.
Forecast and Meteorologist Commentary
MetService meteorologist Ethan Walton-Jones provided the lightning strike totals, while colleague John Law elaborated on the evolving weather pattern. Law likened the incoming rain band to a “volume switch,” suggesting it would add extra intensity to showers but would remain sporadic. He anticipated that thunderstorms would be scattered yet would “clear through quite nicely.” Looking ahead, Law described the weekend as an “improving story,” with heavier showers expected tonight and tomorrow but a general trend toward better conditions. He forecast Sunday to be a “much better, brighter day,” with only isolated showers in the far south.
Wastewater Discharge Incident in Wellington
The heavy rain also challenged Wellington’s wastewater infrastructure. The short outfall pipe at Moa Point, designed to handle typical flows, became overwhelmed and began discharging untreated wastewater into Tarakena Bay. Authorities warned that the contaminated water was likely to travel along the coastline, posing environmental and public‑health concerns. Monitoring and mitigation efforts were underway to assess the impact and to prevent further discharge as the rain subsided.
Summary of the Weekend Outlook
Overall, the weather system delivered a notable bout of lightning, gusty winds, and heavy rain across the upper North Island, prompting widespread alerts and temporary power disruptions. While the immediate threats have begun to ease, the lingering heavy‑rain watches and the potential for isolated thunderstorms mean residents should remain vigilant, especially in areas under watch. The improving trend forecast for Sunday offers hope for clearer skies, but the wastewater incident in Wellington underscores the need for resilient infrastructure in the face of intense rainfall events.