The tropical low between the North Island and Fiji continues to get bigger today – and that is starting to alter its entire shape as it’s pushed and stretched by a large high to the south.

WeatherWatch.co.nz says the impressive tropical low is still forming, but recent changes are pointing towards more of a south east flow over the North Island and less of an easterly flow.  This tiny change has a significant effect on the forecasts, in that a sou’easter is often a dry wind direction for western parts of the North Island.

Latest guidance suggests one of the lows will centre just off East Cape tomorrow, driving in strong to gale force winds and heavy rain.  A rain warning has already been issued.

WeatherWatch.co.nz predicts over 200mm of rain will be likely from this event for some parts of Eastland.

“This slight shift in wind direction will have little change to eastern coastal regions of the North Island.  A nor’east wind is the same as a sou’east wind pretty much.  But once you get over the ranges that small wind flow change is significant, and could mean more sun and less rain for western regions – at least for the next day or two” says head weather analyst Philip Duncan.

The low promises to bring a chaotic week of weather to the upper North Island but the big size of the low means the chance of wind and rain warnings is reduced, as the energy is spread further afield. 

As WeatherWatch.co.nz said on Monday it will bring a mix of torrential tropical rain and some blue sky too.

Winds have been building over Auckland, Northland and other northern areas in the past 12 hours.   Auckland’s forecast today is for mostly dry weather but cloudy periods.  Yesterday rain was predicted for this afternoon but the recent change in shape of the low looks as though it will keep that rain just offshore to the east today.  It’s incredibly close, but the slight wind direction change will see that rain hovering out oversea and less likely over Auckland itself.

“The low has basically gotten so big it doesn’t have enough wind and rain to fill it in – so a big portion of this low has blue skies and light winds in the middle of it”.

“Unlike the lows we had in March, which were short and sharp, this one is very big, very slow and highly unpredictable”.

Mr Duncan says this is one of the trickiest lows they’ve had to predict in a year. 

But those in the upper North Island need to keep up to date with the developing forecasts.  “While some areas may not see much rain, others will see more – especially the east of the North Island. On top of that we expect at least two other lows to form near northern New Zealand in the coming days and into Easter Weekend”.

As WeatherWatch.co.nz said yesterday, most main centres are unlikely to be affected by severe weather from this low – but a windy week, with periods of rain and showers, are still forecast for the North Island.

A large high predicted over the South Island should see a sunny and calm week and Easter Weekend there, while the North Island will have windier, cloudier weather – with rain or showers possible in the north and north east of the island.