An unstable westerly flow covers southern and central New Zealand, with heavy showers likely in some places. For the Westland District, Fiordland, Stewart Island and coastal Southland, there is mostly a low risk of thunderstorms, but the risk is moderate for Stewart Island and Fiordland south of Milford Sound this morning. Any thunderstorms that occur will likely be accompanied by heavy rain with intensities of 10 to 20 mm/h. For the Grey and Buller Districts, also northwest Tasman, there is a low risk of thunderstorms this afternoon and evening. Lastly, for coastal areas from Manawatu to Waitomo, there is a low risk of thunderstorms from evening. No thunderstorms or significant convection expected elsewhere in New Zealand today.

A front embedded in an unstable west to northwest flow moves onto southern New Zealand Thursday morning. There is a moderate risk of thunderstorms for Fiordland and the Westland District south of Haast, spreading northwards to include the remainder of Westland plus the Grey and Buller Districts after dawn. A low risk of thunderstorms extends slightly farther north and east, as depicted on the chart. Any thunderstorms that occur will likely be accompanied by brief heavy rain with intensities of 10 to 20 mm/h, and small hail in the south from late morning. No thunderstorms or significant convection expected elsewhere in New Zealand during Thursday morning.

A front moves north over the South Island in the afternoon and onto the North Island in the evening. Cold air at upper levels is likely to bring unstable conditions and showers to the lower and central South Island. In the afternoon there is a moderate risk of thunderstorms for Westland and also Otago and Canterbury near the main divide as indicated on the chart. These storms may be accompanied by heavy rain, 10 to 20 mm/h and hail. There is a moderate risk of thunderstorms for Canterbury south of the Banks Peninsula and North Otago. Those storms may be accompanied by heavy rain and 5 to 15 mm hail. In the afternoon and evening there is a moderate risk of thunderstorms for Buller and the far west of Nelson. Those storms may be accompanied by heavy rain, 10 to 20 mm/h and hail. In the evening and at night there is a moderate risk of thunderstorms for Kapiti, Taranaki and coastal Waitomo. Those storms may be accompanied heavy rain, 10 to 20 mm/h and hail. There is a low risk of thunderstorms extending slightly east and south from the moderate risk area over the North Island. There is also a low risk of thunderstorms over the far south of the South Island. No thunderstorms or significant convection expected elsewhere in New Zealand during this period.