UPDATE 2:30pm – Not much change going forward, conditions are still very similar to yesterday’s outlook. Here’s our latest honest and detailed outlook for the weekend, without all the hype: 

Heavy snow?

Canterbury still looks like it could well receive a heavy bout of snow this coming Saturday, snowfall eases overnight becoming more coastal by Sunday. Heavy snow to low levels looks possible as the air is quite cold and this low may feed in moisture at just the right time. This forecast may change as we move forward although there is some consistency going forward now – if the snow level shifts by just 100m however it can have a *significant* consequence to the forecast. It’s why snow forecasting is tricky in NZ sometimes!

Snow to sea level?

Yes, the latest shows there does appear to be a chance of Sea level snow, we now have this chance spreading right up the east coast of the South Island during Saturday evening and then overnight. The only thing is that as this chance comes about due to the very cold air moving in moisture levels drop away a fair amount so sheltered spots like South Canterbury may see nothing at sea level. It will be the usual spots like Coastal Otago, Rakaia township northwards along the coast in Canterbury and then sticking along the coast up to about southern Marlborough. It’ll be touch and go but the best chance appears to be on Sunday morning then conditions may resort to sleety showers for the rest of the day with snow flurries staying above about 100m.
 

Snow for any of the main centres?

Dunedin has the best shot at some sea level snow from Saturday evening although don’t expect anything too heavy. Christchurch is the next main centre that may be affected but as is often the case it’s touch and go as to whether the air will be cold enough for sea level snow in the Garden City, the best chance appears to be on Sunday morning currently but amounts will most likely be fairly minimal. Latest data doesn’t support heavy snow in the city…but snow may be falling very close – so as we say this forecast is now “one to watch”.

Timing for the coldest air?

The coldest air arrives over the lower South Island on Saturday afternoon / evening then moves into the upper South Island overnight. Sunday morning and afternoon sees cold air spread northwards over the North Island.

North Island?

It looks like there may be some reasonable snow (if not heavy) overnight Saturday / early Sunday about the Central Plateau and along the east coast but it eases away quite quickly on Sunday morning. Snow should mostly be above 700m however it looks to lower down to 200m by Sunday morning and then that’s the point snow backs away becoming lighter in nature.  
  
So the Central North Island inland and higher altitude highways up along the east coast and Desert Road could be affected by snow overnight Saturday / early Sunday.  Roads may be closed.

To Sum Up: 

The situation is looking to pack some punch but thankfully it is relatively quick moving, expect some heavy snow but perhaps not as much as we had in June. Farmers in the South Island are still well advised to take note, we’ll continue to monitor conditions and put forward any further updates if necessary on Saturday.

The low in the Tasman Sea is colliding with cold southerly air moving up out of the Southern Ocean this weekend. 

A high over Australia looks to be ridging reasonably deeply into the Southern Ocean also so this does indeed look ominous.

– WeatherWatch.co.nz exclusive