Thunderstorms have eased today and conditions are drier in many places but another surge of severe weather is on the way predicts WeatherWatch.co.nz forecasters – and this new surge will be more widespread.

A very deep low near Stewart Island will bring gale force to hurricane force winds across exposed parts of New Zealand over the next three days along with another blast of thunderstorms, hail, squalls and even tornadoes.

While it’s tricky to be too detailed this far in advance we do believe thunderstorms and squalls (a heavy shower with sudden gale force winds) will be more widespread than they were on Saturday, this time stretching up into Auckland and Northland and may even have the energy to spill over into Bay of Plenty, Central Plateau and Wairarapa.

“The risk for tornadoes is very real and certainly expected to be more widespread on Monday and/or Tuesday” says head weather analyst Philip Duncan.  “But it’s also worth pointing out that tornadoes are, in fact, normal in New Zealand.  I guess what hasn’t been so normal is the fact that this year they’ve been hitting populated places rather than forests and farms”.

Mr Duncan says the tornado risk will increase during the day as the front advances northwards.  Auckland will have an increased risk by Monday afternoon or evening and into Tuesday.

But despite the risk the chance of a tornado hitting your home still remains low and WeatherWatch.co.nz advises that people remain calm but simply be aware of squalls and thunderstorms in the area.  “As I said we get tornadoes every winter, but most of the time we don’t know about them until they hit someone’s property”.

Other western areas, from Fiordland to Waikato, will have a similar tornado risk but the risk kicks in earlier – starting overnight tonight in Fiordland and then the risk area will move into Taranaki by late morning.

The same risk time zones exist for thunderstorms, which are expected to be widespread across the western coastline.  Hail and squalls will also be expected.

But not everyone will have severe weather in the west.  “As we saw on Saturday many places had a mostly dry day.  This isn’t one big band of rain moving in, it’s several shower bands, some fasting moving, some slow.  We’ll have a clearer idea as we head into Monday where these showers will be – as many of these showers won’t even form until closer to landfall”.

The government forecaster, Metservice, is also predicting widespread thunderstorms and isolated tornadoes across western New Zealand on Monday.

WeatherWatch.co.nz says unlike the big tornadoes in America these ones are small scale and therefore much harder to predict with great detail. 

“If you see a tornado, get indoors, stay away from windows and find a small room such as a closet” says Mr Duncan.

In eastern New Zealand a mostly dry day is predicted on Tuesday but winds will be strong.  Gale force westerlies are predicting in exposed places from Otago to Marlborough and Wellington to Hawkes Bay.  Gales are also possible in some western areas, in particular Auckland, on Tuesday.

Winds may also reach hurricane force for a time in some areas such as inland Canterbury and around Cook Strait/lower North Island.  Hurricane force is the same speed as Severe Gale (sustained at 120km/h).

– WeatherWatch.co.nz