For the first time in several weeks significant rain bands are moving in to the upper North Island reports WeatherWatch.co.nz.

Latest rain radar shows rain setting in over much of Northland and Auckland with other regions from Taranaki to East Cape northwards likely to receive rain later this afternoon and tonight.

WeatherWatch.co.nz says satellite loops show significant sub-tropical rain cells forming north of the country which are slowly tracking south-south-east towards northern regions.

Head weather analyst Philip Duncan says it is the slow movement of the system, rather than its size, that is the main concern.  “To the east we have an intense blocking high and to the west a developing low.  In between lies New Zealand with a narrow band of rain that currently stretches from the upper North Island well into the sub-tropics.  The front is being held up by the blocking high to the east and therefore some areas could receive enough rain to cause localised slips and flooding”.

Mr Duncan says there isn’t one large band of rain, rather there are small but intense cells that are linked together.  “This makes it a little tricky to pinpoint exact areas of concern, but without doubt northern regions of the North Island, particularly north facing regions like Bay of Plenty, are most at risk from prolonged heavy downpours”.

Heavy rain across Coromandel Peninsula, Bay of Plenty and East Cape could lead to slips, isolated powercuts and even the potential for some road closures says WeatherWatch.co.nz.

The sub-tropical connection hasn’t gone undetected by New Zealand’s only public Lightning Tracker, which shows a number of strikes from an active cell just north of Northland – which is drifting southwards.

WeatherWatch.co.nz predicts coastal parts of Northland and Bay of Plenty, along with Great Barrier Island, Coromandel Peninsula and East Cape are most exposed to thunderstorms – although most activity is expected out at sea. 

“Due to the sub-tropical connections we can’t rule out sudden torrential downpours that could lead to localised flooding and even some wind damage either as a squall or a small tornado or waterspout”.  However Mr Duncan says generally speaking the chances of wind damage is considered very low.

WeatherWatch.co.nz yesterday predicted a brief period of strong winds for Tuesday.  Auckland has had a blustery day but conditions are starting to ease as the main winds track eastwards.  WeatherWatch.co.nz says the bulk of the winds are being caused by the intense high rather than the low.

The high will slowly track eastwards over the coming day or two, taking the strong nor’easters with it. 

“After such a mild Autumn most trees still have their leaves in northern regions but today’s winds coupled with the recent cold spell means there is a lot of leaf debris out there and that will certainly lead to increased surface flooding in urban areas” says Mr Duncan.

The main rain bands will take the next day or two to clear the North Island – welcome news to most farmers and those who rely on rain water. 

WeatherWatch.co.nz says no significant rain has fallen in the north since March.

A showery sou’west change with the sun returning is expected for Thursday and Friday in the north, however WeatherWatch.co.nz is still monitoring the data for Canterbury and Otago with some models suggesting heavy rain on the way for these dry regions, especially later on Wednesday and early Thursday.

Latest data used by WeatherWatch.co.nz says the chance of rain for Canterbury is 80% for the next two and a half days.

“Overall this rain is needed and welcome by most New Zealanders following an incredibly dry April” says Mr Duncan.

One area that won’t be wanting more rain will be Gisborne says Mr Duncan, which has suffered flooding and large slips in recent months.

– WeatherWatch.co.nz