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.
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gparker on 6/05/2011 9:36am
Here in Christchurch it has been day after day of gloom for over a week now, with seemingly early winter temperatures (around 13 degrees). What’s up with this, maybe I should go live on the West Coast, they seem to have the better weather these days, go figure.
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Poppycleo on 6/05/2011 6:33am
Driving to work this morning around 8am and looked over to the west to see a very long dark cloud with a defined edge to it. Looked over again 5 mins later and there was cloud dropping down from the centre in a “tornado” shape. This cloud then got narrower and closer to the ground but didn’t quite reach it. The next minute you could quite easily see the cloud lifting back up into the main body. Very cool to see.
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BQ on 6/05/2011 4:26am
Mt Wellington – Friday 1500 blowing an absolute gale!!
Mt Wellington – Friday 1600 completely calm.
It’s like somebody turned off a switch!
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WW Forecast Team on 6/05/2011 4:54am
Thanks for the update from Mt Wellington! Some very large clouds passed overhead around 3pm – it’s hard to tell on an overcast day just how high they are but the cloud tops are pretty high at the moment. These clouds are quite turbulent inside, creating strong downdrafts (these can also create tornadoes, although we think the chances are low of this happening today). The colder air can then be pushed downwards – creating a wall of strong winds as that cloud passes by. This blast of cold downward air can also be felt – so the temperature can drop in one part of the city but not in others. Once the big clouds pass the warmer air surrounding slowly moves back and the winds ease. That sound like what you may have experienced?
Regards
– WeatherWatch Weekends
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BQ on 6/05/2011 5:57am
hey thanks Phil. Very good week for weather watching.Very good week for reminding us not to be so complacent as well!
I definitely observed that phenomenon on Tuesday right as the tornado struck in Albany. The air being pushed out of the cloud bank was very chilled!
The strong winds today weren’t cold feeling tho – certainly not as cold as Tuesday’s. Lots of low rising scud over Auckland tho – so there must be some fairly decent updrafts around sucking it all up. Would be nice to have some of those altitude/3d type of radars that the US has just to see what’s happening up there eh!
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BQ on 6/05/2011 10:12am
so any idea where that low in the Tasman intends to head .. over a 24hr satellite loop it’s heading north! The last forecast I heard had it tracking over Wellington/Nelson somewhere .
Will it U-turn will it not?! Seems very undecided in it’s merry ways!
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WW Forecast Team on 6/05/2011 10:48am
It’s sort of getting a speed wobble and will wobble northwards before pulling to the south east and probably cross central NZ (Cook Strait area) on Sunday.
– WW
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Guest on 6/05/2011 4:18am
Thunderstorm over West Auckland just now
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WW Forecast Team on 6/05/2011 4:27am
Yep, a few certainly just along the western coastline there – however the majority today have been well offshore.
Looks like some more thunder activity moving into Northland this evening – might make it to Auckland too – one to watch!
– WW
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