Can’t take anymore – a waterlogged farm near Papakura, (South Auckland).  Photo/weather watch visitor Foehn MacKenzie.

THUNDERSTORMS have started to develop over northern New Zealand on the tail end of a front that passed through this morning.  Over 200 strikes an hour were being picked up on the Lightning Detector at weatherwatch.co.nz but that has halved in the past hour.

The thunderstorms are mostly over Auckland however a few remain over Northland.  The Weather Watch Centre advises people to stay indoors until the thunderstorms have cleared.  The Centre also warns of the risk of isolated surface and flash flooding between Central Plateau and Northland due to the heavy downpours and slow nature of the system.  Thunderstorms should clear Auckland in the next hour or so but further thunderstorms are possible overnight and tomorrow.

The main band of rain is now moving into the lower North Island and upper South Island.  The low fueling the rain is currently the largest low pressure system in Australasia and lies off the North Island’s west coast.

Head weather analyst Philip Duncan says the rain has the potential to cause isolated pockets of flooding but he doesn’t expect we’re in for a repeat of July’s rainstorm.  “The rain is certainly heavy across northern and western facing areas but I don’t think it will be with us long enough to cause a repeat of July’s big rains.  There’s also been a decent ‘breather’ periods since then and now”.

He says a lot of heavy rain is falling in the catchments of the Waikato River and that may pose some serious concerns early next week as the storm surge moves down to low lying areas.  Mr Duncan says any worried residents along the Waikato River should be up to date with the latest news from Environment Waikato who is closely monitoring the rain: www.ew.govt.nz

Image updated every 12 hours at 6 O’clock:  This image shows the predicted humidity levels across New Zealand for Sunday.  Dark blue is 90 to 100% humidity (over NZ) – this compares to orange over the Australian desert which shows humidity at just 10%.  Image/weather.com

The air stream moving over the country is certainly a humid one.  The low is pulling air down from the sub-tropics – as north as New Caledonia – meaning much of the country will see humidity levels rise between 90% and 100%.

As predicted by the Weather Watch Centre yesterday, winds are strong but aren’t strong enough to cause any real damage.  This morning gusts of around 100km/h were reported in some exposed coastal parts of Auckland but the city itself, along with New Plymouth and eastern parts of Northland, only recorded gusts to 65km/h.  Winds over the North Island have eased considerable over the north as the centre of the low – which is usually calm – moves in.

Meanwhile the lower part of the South Island had a cold and clear start to the day – at 8am it was -3 in Queenstown and frosts were recorded right across Southland and Central Otago.  High cloud is likely to thicken across the region today as the low moves closer to the country.

The centre of the low is likely to cross Northland during Monday morning, with the main rain band much further south, over Canterbury.