A vein of subtropical rain extends from New Caledonia down to New Zealand’s North Island however the bulk of the energy lies out at sea north of Northland.
With a low in the Tasman Sea falling apart and a large high over the Pacific to our east holding firm, the subtropical airflow is being squeezed down a specific line over northern New Zealand with hills and ranges also affecting the rain clouds (making it dry for some, wetter for others).
However in set-ups like this it’s normal to have a very fine line between drizzle that amounts to very little and a sudden set in rain that can cause localised flooding. The low is weakening but the energy to the north will remain and could drift back to northern New Zealand from Sunday to Wednesday next week bringing muggy conditions, isolated deluges and even some thunderstorms.
As of mid Thuesday morning the main rain band over northern New Zealand wasn’t overly dramatic – however later today some larger downpours will flare up. The bulk of them will be out at sea and around places like the Hauraki Gulf, but some will clip land and the slow moving heavy nature means flooding and slips are possible in some pockets. A tricky forecast to lock in with specifics when the downpours are small in size and surrounded by large areas of patchy moderate to light rain or even just drizzle.
Very generally speaking the front falls apart on Friday morning over northern areas but could drift back into Northland. Saturday and Sunday have a similar set up for northern NZ with muggy conditions and the chance of these downpours returning from the sub-tropics.
Next week could see a return to very heavy downpours throughout the North Island and even as far south as the upper South Island ranges due to the light, humid, airflow out of the sub-tropics.
The bulk of this weather pattern is currently affecting the North Island.
– Global maps show the centre of the low to the NW of the North Island and the tropical thunderstorms and heavy rain extending down into the New Zealand area but mostly falling short of tracking across the country. A large high remains to the east – as that shifts away later on Sunday and into Monday it will allow more of this sub-tropical energy to slide back down over New Zealand, most likely in the form of downpours and isolated thunderstorms.
– Maps by The Weather Company