MetService: Unstable conditions affect much of the country today with thunderstorms possible in many areas, especially the west of both islands.

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An active front containing embedded thunderstorms over Buller this morning sweeps over the North Island this afternoon and evening. To the north of this front, a trough near Waikato and west of Auckland contains heavy showers which may turn thundery prior to the frontal passage later today. To the south of the front, a cold upper trough with heavy showers and isolated thunderstorms is spreading onto the lower South Island.

The highest risk of storms today is with the front in western areas from Buller to Taranaki, including the Outer Sounds, northern Wellington and Horowhenua Kapiti Coast. Thunderstorms in these areas are expected to bring heavy rain of intensity 10-25mm/hr and squally wind gusts reaching 110km/h.

Additionally, there is a lesser risk of small tornados or waterspouts in coastal places.Further north, there is a moderate risk of thunderstorms as far north as Auckland and across to Taupo and Bay of Plenty, bringing locally heavy rain and gusts reaching 90km/h (especially in the west). Auckland, Coromandel Peninsula and Northland have a low risk of thunderstorms today.

In the cold air behind the front, isolated thunderstorms are currently occurring in Fiordland and there is a moderate risk of these continuing into this afternoon and spreading to Westland and Buller this afternoon and evening. These storms may bring brief heavy rain and small hail.

Finally, there is a low to moderate risk of storms from North Otago up through the Canterbury coast and Plains this afternoon as winds turn southwest. Any storms that do eventuate have the potential to produce localised heavy rain and hail of diameter 5-15mm.
 

– MetService