Weather Watch: Thunderstruck!

Forked lightning over Auckland. Photo / Simon Williams, weatherwatch.co.nz

The big low responsible for last night's amazing thunderstorm over Auckland is finally making landfall this afternoon across Taranaki. The low can be quite clearly seen on animated rain radar images, with showers swirling around a clear centre, as it heads over land. Now that it's off the Tasman Sea it will weaken (no more fuel) meaning further thunderstorms are unlikely for those northern and western regions that have been rumbled over the past 48 hours.

WeatherWatch was sent over two dozen amazing photos of the lightning last night in Auckland - see this fantastic gallery here.

The thing I loved about last night's storm was how quickly it appeared. Around 5pm the rain radar suddenly showed a line of heavy showers forming along the length of the Waitakere Ranges. Within minutes they had exploded into thunderstorms with lightning so bright that it caught my attention even with the sun shining brightly. A house in Massey had its mains knocked out while a superette in Kelston needed the fire service to urgently unblock the drains when the deluge flooded the shop.

A large hail storm spread across New Lynn and Te Atatu South while hail and near non-stop thunder pounded Helensville. By 7pm the storm's centre had shifted to northern parts of Auckland then out in to the Hauraki Gulf just in time for darkness to fall, putting on a magnificent electrical storm well in to the evening and kept many photographers cameras clicking.

But the low is now weakening and falling apart. It has one last gasp of energy later today, in the form of a band of heavy showers moving in to western parts of the North Island. It's unlikely they'll contain any thunderstorms for western and northern regions - but there is still a slight risk.

The risk for thunderstorms has now shifted to the east coast of the North Island from Gisborne to Wairarapa. MetService believes there's even a chance for Severe Thunderstorms across Hawkes Bay today as that low pushes it's energy eastwards.

So what lies behind this low? Well it's a classic sou'west/nor'west flow right across New Zealand. Today that gusty sou'wester will kick in right over New Zealand and remain in place tomorrow. But by Friday winds will shift nor'west ahead of the next frontal system. Rain will spread to many places this weekend (sorry!) with a cold southerly change spreading up the nation on Sunday - that could be good news for Auckland, Waikato and Bay of Plenty though - as it usually clears the rain clouds quickly.

I'll have more details about the upcoming weekend weather in my blog on Friday.

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Top: Forked lightning over Auckland. Photo / Simon Williams, weatherwatch.co.nz