While news of further tornadoes has dominated media organisations over the past 24 hours WeatherWatch.co.nz this morning said the risk of thunderstorms and tornadoes was, in fact, going to be much lower today – but the risk for Saturday has now increased.

The timing change is due to the slow nature of the low, as head weather analyst  Philip Duncan explains.  “The centre of the low is still over the central Tasman Sea but tomorrow the squally showers, which are near the centre, will move closer to New Zealand.  This puts the western coastline of the North Island at a higher risk of thunderstorms than it does today”.

Mr Duncan says almost all thunder activity today has been well offshore, despite the prediction by other forecasters.  But Mr Duncan defends the changing forecasts “It is a tricky system to predict, it’s big, it’s slow and if you look at a satellite map you can see the clouds and rain bands are all broken up.  It’s not a straightforward system and people need to regularly check forecasts over the coming day or two”.

WeatherWatch.co.nz was the first weather organisation to mention the risk of further tornadoes yesterday but today was the first to scale back those predictions.  “We don’t like the unpredictable nature of this system anymore than other kiwis living in the upper North Island, but the weather is especially chaotic at the moment.  We need to stay on top of this system and if that means extra updates then that”s what we’ll do”.

He says WeatherWatch.co.nz has been “inundated” with people worried about more tornadoes.  “My advice is to not panic, the chance of a tornado forming today is very low and tomorrow it’s still fairly low.  Even if one does form, the chance of it hitting your house is also very low.  So long as people are keeping an eye on the skies, current conditions and the latest weather forecasts there is no reason to be living in fear”.

On Saturday a more active area of showers, associated with a cold front, will push into western and northern parts of both islands – particularly the North Island and north west of the South Island.

WeatherWatch.co.nz has singled out Taranaki and Nelson as “high risk” areas for thunderstorms and says a “low risk” of an isolated small tornado (EFO or EF1 rating) is possible in the area.  For other areas, such as Auckland and western Waikato and Northland the risk of tornadoes is “very low” but cannot be ruled out.  A “very low” risk remains for Bay of Plenty today and again on Saturday for an isolated tornado.

MetService is the other way around – predicting a moderate chance of small tornadoes today and no chance tomorrow.

There are currently no official thunderstorm warnings or watches in place.

WeatherWatch.co.nz predicts the centre of the low will cross near Cook Strait and Taranaki on Sunday which could prompt heavy rain warnings for the Nelson Ranges and Mt Taranaki with a risk of gales force winds too.

MetService also predicts a “low” chance of heavy rain for Nelson Ranges and Mt Taranaki on Sunday and also has confidence, rated low, of northerly gales for Taranaki, Wanganui and Wellington on Sunday.  They have “moderate confidence” of heavy rain in Southland, Otago and Canterbury south of Ashburton on Sunday too.

At the time this story was published MetService had rain warnings in place (see below for details) for Bay of Plenty and Gisborne.

WeatherWatch.co.nz will have more hands on deck this weekend to monitor the weather conditions as a week of rough weather continues.

Metservice Rain Warnings (issued 8:32am Friday)

Bay Of Plenty

Heavy Rain Warning, Areas Affected: The ranges of Bay of Plenty and Gisborne north of Ruatoria In the 15 hours from 9am to midnight Friday expect 70 to 90mm of rain. Intensities may reach 25mm per hour at times in isolated thunderstorms. West of Whakatane, the rain will probably ease after midnight Friday, although a risk of further heavy falls remains. East of Whakatane and north of Ruatoria, the rain will probably intensify after midnight Friday, with a further 100mm or so falling in this area between midnight Friday and noon Saturday. 

Rotorua

Heavy Rain Warning, Areas Affected: The ranges of Bay of Plenty and Gisborne north of Ruatoria In the 15 hours from 9am to midnight Friday expect 70 to 90mm of rain. Intensities may reach 25mm per hour at times in isolated thunderstorms. West of Whakatane, the rain will probably ease after midnight Friday, although a risk of further heavy falls remains. East of Whakatane and north of Ruatoria, the rain will probably intensify after midnight Friday, with a further 100mm or so falling in this area between midnight Friday and noon Saturday. 

Gisborne

Heavy Rain Warning, Areas Affected: The ranges of Bay of Plenty and Gisborne north of Ruatoria In the 15 hours from 9am to midnight Friday expect 70 to 90mm of rain. Intensities may reach 25mm per hour at times in isolated thunderstorms. West of Whakatane, the rain will probably ease after midnight Friday, although a risk of further heavy falls remains. East of Whakatane and north of Ruatoria, the rain will probably intensify after midnight Friday, with a further 100mm or so falling in this area between midnight Friday and noon Saturday.