The large and deep low pressure system approaching New Zealand is complicated to forecast due to so many moving parts – but we’ve done our best to identify what the key issues will be each day and where. With such a large low more fine tuning will be needed over the next 48 hours.
THE GENERAL SET UP:
THURSDAY: Sub-tropical northerly winds and rain moves in on Thursday with heavy falls in the north and west of both islands. Winds will be strong, possibly gale in some places, but likely below damaging.
FRIDAY: Colder south easterlies arrive in the lower South Island on Friday (especially Canterbury & Otago) with heavy snow developing above a few hundred metres and heavy rain at sea level. Showers and mild nor’westers continue for the North Island with overnight snow possible in Central Plateau.
SATURDAY: Wintry, windy, south easterlies from Canterbury to Hawke’s Bay with winds possibly severe gale again through Cook Strait. Easing elsewhere and becoming sunny/dry.
Severe Weather Risks around NZ until Saturday:
With such a large low they operate quite differently to, say, a tropical storm which has all the worst wind and rain near the very centre. With these large lows that develop around New Zealand the centre can actually be quite calm and sizeable – so as they low crosses over some areas will be calm and dry. Our mountains and ranges also play a huge role at increasing or decreasing winds and rain. The energy with this system is significant but thankfully it is spread out over a greater distance and this reduces the severity – and also places a big chunk of severe weather out at sea.
With this low pressure so large there is some good news on the wind front – the bulk of the gales will be out at sea, surrounding New Zealand but mainly avoiding land. There are some risks, which we’ll update and fine tune each day:
POTENTIAL TRAVEL ISSUES:
– WeatherWatch.co.nz has daily news and video updates about this low, check back for more.
on 18/07/2017 1:54am
Many thanks Phil, I am grateful for your updates. We don’t even feature on MetService’s outlook map at all and forecasts are pfft. I am pleased for your forecasting severe winds in Cook Strait as they tend to slam us in low pressure, as does any severe S/SE. There have been few decent Southerlies this winter, but we have already been slammed by severe winds which have caused damage to my house. Warnings the night prior are useless, hence your earlier warnings are far superior. The US models work for us where the UK ones are junk. – Paekakariki.