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Updated FAQs: Incoming heavy snow, rain & gales for some of New Zealand

This week is a very busy week weather-wise with heavy snow, heavy rain and severe gales in the forecast for various parts of the country.

While quite a lot is happening it’s worth noting the majority of populated places may not have “severe” weather – but the incoming blast of weather is likely to have significant impacts on some farmers and travellers.

All alpine highways are expected to get snow this week, including the Desert road in the North Island and the Rimutaka Ranges around Wellington. 

Snow is likely to fall to sea level for a time in Southland and Otago, however Canterbury the level may be 100 metres. Keep in mind 100 metres down a road is a very short distance – and this is directly above. So therefore Christchurch (and Timaru and Oamaru also on the coastlines) have some risk but not a high risk yet.


Frequently Asked Questions (FAQs)

What is happening and when?
On Tuesday a cold front will move into the lower half of the South Island, spreading over the entire South Island by early Wednesday morning – and then into the North Island over Wednesday, Thursday and Friday.  

At the same time as this southerly moves in a new low pressure system will be forming over the North Island – and will drag sub-tropical rain into the colder southerly heading north.  This will create both heavy slow moving rain in the east and heavy ongoing snow higher up.

Also, as this low deepens a large high to NZ’s south west will be spreading in – creating a “squash zone” of easterly quarter gales around the Cook Strait area (upper South Island/lower South Island). This squash zone may see gales reach severe gale for a time here.

Meanwhile with this low over the North Island it will help buffer some of this weather, creating for large areas of calm and dry for some North Islanders – amongst the downpours around it.


Where will the snow fall?
Please note snow may be brief and not even settle for some, for others it may be heavier and settle for days.

Just like with rain and showers, snow can be patchy and therefore heavier for some while others nearby may completely miss out. This is not a major storm – but it is likely the lowest snow fall of the year so far. Snow at higher altitudes (ie above 200 or 300m) may be quite widespread in the South Island and above 400 or 500m in the North Island.

Snow to sea level looks likely for a time in Southland and Otago and perhaps Canterbury.


Which main centres will get snow?

At this stage WeatherWatch.co.nz believes the following main centres may get snow for a time on Tuesday or Wednesday:
South Island: Dunedin, Gore, Alexandra, Queenstown, Cromwell, Arrowtown, Wanaka and Ashburton. (We may not have listed all towns, but if you live in the area no doubt you get the idea).

Christchurch – at this stage – is borderline to get snow, but we’ll monitor it. Snow in Canterbury may be down to 100m but again, like rain, amounts and snow levels will vary across regions due to the mountains and ranges, coastal conditions and wind/air flows at the time…and timing will matter too, overnight has a higher chance of pushing snow down to lower levels. There is some chance for snow in Christchurch.

North Island: Waiouru, Ohakune, Taihape are all highly likely to receive snow, so too National Park. Stratford and Eketahuna both have some chance. Taupo is not expected to get snow but it will be nearby and low on Mt Tauhara and surrounding plateau/hills. 


Which State Highways may be affected?

Many South Island highways will be affected around Southland, Otago, Canterbury and through/over the Southern Alps for a time. ALL ALPINE HIGHWAYS are likely to get snow at some point and some may well be closed. State Highways and side roads in Dunedin may be impacted for a time but it’s unclear how heavy it will be. History shows even just 1 or 2cms in Dunedin can stop the city from moving.

In the North Island SH2 over the Rimutaka Ranges is likely to be impacted, perhaps on Wednesday night by both heavy rain, possibly slips, possible gales and then snow on the summit.

SH1 the Desert Road is HIGHLY LIKELY to receive snow, as too are ALL HIGHWAYS AROUND MT RUAPEHU – but unclear at this point if it will be heavy enough to cause closures.  SH5 from Napier to Taupo may also likely be impacted by snow, rain or slips later on Wednesday through to Friday with snow expected to fall down to Rangitaiki.


Which airports may be impacted?

SNOW/ICE: Hard to say as airlines, airports and pilots make decisions on whether they will fly or not, but it’s fair to say the weather could impact flights/airports at Dunedin, Invercargill and Queenstown. This may therefore impact some other flights/airports anywhere in NZ, especially if snow grounds any planes at an airport.
ADVERSE WEATHER may impact Wellington airport, Paraparaumu, Blenheim (heavy rain, severe gales possible), esp around Thursday.


Which ski fields will get snow?

Every single one of them (with the exception of Auckland’s Snow Planet which is indoors!) 🙂


How far north will the snow fall?

The tops of the Gisborne Ranges and possibly Waikato (ie the summit of Mt Pirongia, Mt Te Aroha).


Is it a storm?

No it is not. In the South Island it’s a fairly straight forward snowy/cold period of weather for mid-winter/July. It’s definitely worth warning about though, especially for farmers and those who need to use the highways and airports. However as the cold change moves into the North Island things get far more complicated due to a large low expected there mid-next week. This low will create a “squash zone” between a large incoming high later in the week to the south west – and this may well generate severe gales winds between these two big pressure systems somewhere over central NZ (Cook Strait area). This may also feed very heavy rain into eastern areas of the Upper South Island and/or lower North Island later this week, which localised flooding a possibility.


What’s the timing of it again?

– Starts Tuesday AM in Southland.
– Reaches Otago and Canterbury into Tuesday PM, locking in properly by Wednesday AM.
– Wednesday PM, across Thursday and Friday AM for the North Island ranges and Central Plateau.

Government agency MetService is funded by the NZ taxpayers to provide warnings. Please keep up to date with their information too.

Will it snow in the main centres?
Snow is likely in Dunedin but borderline in Christchurch City. Snow is not forecast in Wellington’s CBD but it is possible higher up in Wellington’s Hutt suburbs for a time. Check our Detailed forecasts – we’re monitoring the snow as best as we can!

How often are you updating my forecast?
– Our 1500 forecasts + hourly forecasts for every one of those 1500 locations
are updated hourly. (thanks to Wunderground) 

A tip for the hourly forecasts: Once temperatures get down to about 3 or 4 degrees with over 40% chance of rain that’s when snow is possible (if there is no mention of snow in the general text forecast, as for some areas the snow may only be briefly overnight and this won’t be captured in a general daytime text forecast). FYI: Snow is highly likely when moisture levels are above 60% with air temperatures below +2C degrees.

You can search our 1500 forecasts herethey cover basically every small Kiwi Community, City Suburb and NZ Town in the North Island, South Island, Stewart Island, GBI, Waiheke and even the Chathams.

All forecasts go 10 days out with additional hourly forecasts for every single day – and all include % of rain (which if the air temp is below +4C may turn to snow, especially +2C and below).

WeatherWatch.co.nz is New Zealand’s only weather forecaster to have such detail freely available to the public thanks to our partnership and power of global giants Wunderground/IBM along with our eyes and ears based in every region here in New Zealand.


– Tuesday AM Future Rain & Snow Radar shows a low hugging the Antarctic coastline and sending a cold front into the lower South Island, eventually reaching the North Island Weds/Thurs/Fri. A high pressure system should come in behind this for a short time (a couple of days) bringing frosts but drier weather – this incoming high from the SW will also help produce a ‘squash zone’ of gales over central New Zealand later this week. This Map courtesy Weathermap.  See 10 days of Future Rain Radar by clicking.tapping here.

 

– Weatherwatch.co.nz, New Zealand’s weather news & forecast authority.

Comments

Guest on 10/07/2017 1:39am

It would be extremely rare for Invercargill airport to be affected in a SW flow…… thanks to Stewart Island.

WW Forecast Team on 10/07/2017 2:31am

Agreed, but there may be visbility or other weather issues for flights trying to get in and out of Southland, or nearby airports, over the next couple of days.

– WW

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