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Very deep low to bring a real variety of weather

A deep low is developing around New Zealand with gales, intense winds in some pockets and very low air pressure at the centre – but not everyone will have bad weather.

With the low so massive that it engulfs New Zealand it’s easy to assume everyone’s in for rough weather. But larger lows often spread the energy further afield, so as the centre of the low crosses the South Island on Friday there will be a real variety of weather around the country with a showery mild north and a stormy wet south.

View/Share our latest weather forecast VIDEO on this deep low with Philip Duncan

Let’s start with the centre of the low. The centre is where the winds are calmest. Across Friday this calm centre tracks across the upper South Island and towards North Canterbury and the Pacific Ocean. Rain is likely but the strongest winds are further out from the centre.

Winds circle clockwise around the centre which means the North Island has nor’westers (mild) and the South Island south of this centre will have sou’easters (colder).

The bulk of the heaviest rain is in the southern half of the low – in other words, the South Island’s east coast is most exposed to heavy rain that may cause slips and flooding. Mainly Otago, Canterbury and maybe Southland. These areas may get 150 to 200mm of rain around coastal hills, which may well cause slips, flooding and affect travel on highways/roads.

In the North Island there will be heavy rain (mainly today and tonight) then by Friday there will be mild nor’westers and showers.  This means the east of the North Island will be very different to the east of the South Island at the same time on Friday with the centre of the low seperating them apart. The nor’west flow in the North Island means regions like Hawke’s Bay and Gisborne may have a fairly sunny or dry Friday with highs up to 17 or 18 degrees, while patchy rain or showers affect the western North Island across the day.

It’s a big system and will take at least 72 hours to cross New Zealand. 

As the centre of this low drifts further east on Friday and then Saturday we may see rain turning to heavy snow in the mountains of the South Island and therefore Alpine Passes. Rain in the east of the South Island and north of New Zealand looks to ease later on Saturday.

While rain in the Upper North Island on Saturday doesn’t currently look severe it may be heavy enough to cause localised slips and minor flooding due to so many areas reaching saturation point.

– Image / Noon Friday shows the centre of the low around North Canterbury and drifting out into the Pacific. The low is so big it smothers New Zealand in rain clouds but the east of the North Island and south west of the South Island (Fiordland) look mostly clear around Friday afternoon thanks to the large mountains/ranges. The heaviest rain and/or strongest winds look to be in the SE and South of the South Island on Friday PM / Weathermap



Guest on 20/07/2017 7:24am

It’s a non event in Auckland so far. Hopefully it will stay this way.
If the mainstream media was to be believed, we are all in for a serious time. Is this accurate, or just more sensationalism from them?

WW Forecast Team on 20/07/2017 8:17am

Oh totally sensationalism. Auckland Civil Defence called us today as they were perplexed by the two official Government forecasters and mainstream tabloid media outlets etc. Auckland will just have rain from this event. And showers. Normal winter weather for the most part up here.

We know some people get tired of us pointing out the hype in mainstream media and Government forecasters. But we hope in time these people see that their taxes fund this misleading hype – it’s not our free service which spends a great deal of time trying to clarify it for people (and Civil Defence now). New Zealanders deserve better than this – after all we’re the only country on earth to make taxpayers fund two public forecasters (NIWA and MetService) and they are now both competing for the biggest headline in the mainstream news media.

The focus/care on accuracy and helping the public is something of another era it seems…yet we all have to fund them…actually fund both of them …even though both are aggressively commercial and don’t need funding in this day and age. 150 million dollars a year to them. $0 to us, despite Government agencies and Civil Defence now coming to us to clarify on a frequent basis. Weird times in New Zealand – but the public don’t seem to care too much about this.

Philip Duncan


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