A large and deepening low is approaching New Zealand for Thursday and Friday and part of Saturday with rain being the main feature, but gales are in the mix too.

It’s a very different set up to last week that saw one area of focus producing severe weather over a long period of time (mainly around Cook Strait and the lower half of the North Island).

This next set up is a considerably bigger and stormier low but bigger also means the energy is spread much further afield and has many more moving parts. It’s complicated, messy – but the risk for areas of severe weather exists in both islands with rain being the main feature in our view, along with gales for some locations too.

THE GENERAL SET UP:

THURSDAY: Sub-tropical northerly wind and rain moves in on Thursday with heavy falls in the north and north east of the North Island and for the South Island’s West Coast. Gales are possible in various places. Rain may not arrive until overnight for some areas in the east.

FRIDAY: Heavy rain spreads into various parts of the South Island and eventually focuses on the east coast. Snow is no longer a major concern for us as this event looks too warm, but snow may still be heavy for the Alpine Passes. The centre of the low is calm, but gales wrap around it and may reach severe gale in the lower South Island later on.

SATURDAY: Colder with windy southerly quarter winds and rain in the east of both islands easing gradually with sunny weather spreading elsewhere. Gales and even severe gale still possible for a time in eastern areas of the South Island (coastal) and into Cook Strait.

---

Severe Weather Risks around NZ until Saturday:
This storm is different to the localised severe weather we saw in New Zealand last week. Geography and the way the air pressure systems lined up created that intense belt of wind through Cook Strait and heavy rain in Wairarapa and Manawatu. This system also has a squash zone, mainly in the lower South Island on Friday between the centre of the low and the incoming high to the south west. But gales are also possible right around the low due to the depth of this air pressure system – however gales reaching damaging heights is another category and that may not be so likely in our view for many places – but still possible for some.

---

HEAVY RAIN LOW DOWN / SNOW HIGH UP:

THURSDAY

• North Island: Heavy rain develops in the north of the North Island (highest risk looks to be Bay of Plenty to East Cape where flooding is possible at night/overnight. Rain eases later in the day in the west and overnight further east.
• South Island: Rain at times on the West Coast, heavy around South Westland in the morning and then heavy around Nelson later on where it will set in overnight as the centre of the low comes in.

FRIDAY

• South Island: Heavy rain in the east, especially Otago and Canterbury. Rain may fall in many other parts of the South Island due to his deep low crossing over the island on Friday and deepening further for a time. The air will generally be too warm for snow to low levels, but heavy snow is still possible on the Alpine Passes late in the day or overnight.
• North Island: Showers from the west, some heavy.

SATURDAY:

• South Island: Rain lingers in the east, like Canterbury/North Canterbury for much of the day, easing later. Flooding possible. There may be some early snow high up too in the Alpine Passes.
• North Island: Showers with windy southerlies return to Wellington, Wairarapa and other parts of the lower North Island.

---

GALES/SEVERE GALES:
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:

THURSDAY:

• A burst of northerly winds accompanying the main North Island band of rain may see blustery conditions and some coastal gales, but generally well below damaging threshold. Winds most likely in the north and north east of the North Island.
• Strong NE winds may also hug the South Island’s West Coast but again damaging winds not expected at this point.

FRIDAY:  

• Generally mild and windy around the North Island, winds mainly below gale force though. 
• SE winds pick up around the South Island, rising to severe gale later in exposed parts of Southland, Otago and the lower West Coast. These winds peak Friday PM or into early Saturday.

SATURDAY:

• A burst of blustery, strong winds moves up the eastern South Island (mainly Canterbury/North Canterbury) but eases gradually.
• Severe S to SE gales may develop for a time around Cook Strait and possibly Wellington Airport.

---

POTENTIAL TRAVEL ISSUES:
THURSDAY:

• Motorists: Rain may cause some issues (slips and flooding) for Highways in the upper half of the North Island, especially around Bay of Plenty and East Cape/Gisborne at night.

FRIDAY:

• Motorists: Rain may cause slips and flooding across Highways in the South Island – especially eastern areas, but generally the risk applies across the entire island at varying times, but is mostly in the east.
• Motorists: Snow in the Alpine Passes late in the day/night/or overnight, could cause issues 
• Flights/Motorists: Severe Gales developing later *may* affect some flights in Southland and Otago (very much depends on timing and peak gusts). Winds may also make driving hazardous for some.

SATURDAY

• Flights: Severe Gales may delay or cancel flights in Canterbury and Wellington – but still too early to lock in. Check our daily updates for more details. 

– WeatherWatch.co.nz has daily news and video updates about this low, check back for more.