Key Takeaways
- A severe thunderstorm watch was issued for several parts of the South Island, including Timaru, Ashburton, Central Otago, Southern Lakes, Dunedin, and Southland.
- The storm brought widespread and large hail, heavy rain, lightning, and strong winds to the region.
- MetService confirmed that the most severe hailstorms were caused by a supercell storm in the southern Canterbury Plains region.
- The storm was considered one of the year’s most intense, with reports of hail blocking roads and flooding cars.
- No significant damage to crops has been reported, but the storm still poses a risk to driving and outdoor activities.
Introduction to the Storm
The South Island of New Zealand experienced a severe thunderstorm on Saturday afternoon, bringing widespread and large hail to the region. The storm was considered one of the year’s most intense, with MetService issuing a severe thunderstorm watch for several parts of the island. The watch was in place for regions including Timaru, Ashburton, Central Otago, Southern Lakes, Dunedin, and Southland, with some areas experiencing heavy rain, lightning, and hail. The severe thunderstorm watch has since been lifted, but the storm still poses a risk to driving and outdoor activities.
The Storm’s Impact
The storm had a significant impact on the region, with reports of hail blocking roads and flooding cars. NZTA dispatched crews to State Highway 8 between Timaru and Fairlie after receiving reports of hail blocking the road. The storm also caused poor visibility and surface flooding, making driving difficult. MetService meteorologist Devlin Lynden said that the storm was unusual in its intensity, with one of the forecasters describing the cell over Canterbury as one of the strongest they had seen this year. The storm’s impact was not limited to the roads, with the Ashburton District Council reporting that its roading maintenance contractor was out clearing street gutters to ensure stormwater could drain away.
The Science Behind the Storm
The severe hailstorms were caused by a supercell storm in the southern Canterbury Plains region. A supercell is a powerful thunderstorm with a rotating updraft, which allows the storm to last longer and become more intense than typical thunderstorms. This rotation increases the risk of severe weather such as large hail, damaging winds, and heavy rain. MetService confirmed that the supercell storm was responsible for the most severe hailstorms, with the storm’s intensity and longevity making it a significant event. The storm’s rotation and updraft also made it a complex system, with multiple factors contributing to its severity.
Agricultural Impact
Despite the storm’s intensity, there have been no reports of significant damage to crops. Horticulture New Zealand’s regional representative, Chelsea Donnelly, said that there had been no reports of damage to crops so far. Two farms near Ashburton contacted by RNZ also reported that the severe hail storms did not reach them. However, the storm still poses a risk to crops, with MetService warning that large hail has the capacity to cause significant damage to crops, orchards, vines, glasshouses, and vehicles. The storm’s impact on agriculture will likely be closely monitored in the coming days, with farmers and growers assessing any damage and taking steps to mitigate its effects.
Conclusion and Next Steps
The severe thunderstorm that hit the South Island was a significant event, with widespread and large hail causing disruptions to roads and outdoor activities. While the storm’s impact on agriculture appears to be limited, the risk of damage to crops and other infrastructure remains. MetService will continue to monitor the weather, providing updates and warnings as necessary. The public is advised to take shelter immediately if severe weather approaches or if they feel threatened. With the storm now passed, attention will turn to assessing the damage and taking steps to recover and rebuild.
