Computer modelling continues to show a sub-tropical low near New Zealand at Easter but so far the forecast for Easter weekend is still proving a little tricky to predict says WeatherWatch.co.nz.

For much of the week it appeared that a sub-tropical low could affect the weather for the second half of the long weekend in the upper North Island and while that scenario is still on the table other factors are going to play a part.

“It appears that there will certainly be a vulnerable area for low formation north west of New Zealand” says head weather analyst Philip Duncan.  “The area is fairly active at the moment and even today we have a depression near New Caledonia which can be clearly seen on the satellite map with Fiji Met Service saying there is low to  moderate chance it could briefly become a cyclone”.

Mr Duncan says that, that low won’t survive for too much longer but points out there will be little change in the atmosphere over the Coral Sea in the coming week.

By Good Friday a large high should still be in control of much of our weather here in New Zealand however a deep low in the Southern Ocean may bring in some wind and rain for Southland and possibly coastal Otago and Fiordland.

Image — A likely Easter Monday scenario – a high pushing in from the west and a sub-tropical low forming to the north west. It all comes down to the timing of that incoming high as to whether or not it can protect the upper North Island all weekend long / ECMWF

On Saturday next weekend the big high – that will push in this coming Monday – will be departing to the east of New Zealand.  “This could allow a weak cold front from that Southern Ocean low to push up the eastern South Island and into Wellington”.

By Easter Sunday and Monday a new high will push in from the Tasman Sea – our third substantial high this month.  “However also on Easter Sunday and Monday we think a low will be forming just north west of New Zealand.  The models at the start of this week picked it directly hitting us on Easter Sunday, but today those same models are picking it will lie just north of the country” says Mr Duncan. “There’s still plenty of uncertainty”.

Supporting weather data says there is currently just a 20% chance of rain for the upper North Island on Easter Sunday and Monday.  Wellington has a 30% chance of rain on Saturday while Christchurch has only a 10% chance.  Dunedin has a 30% chance of rain on Saturday.

As we get closer to Easter we’ll be able to fine tune the forecasts significantly and by mid week we’ll have a detailed region by region forecasts with a travel forecast issued on Thursday.

– WeatherWatch.co.nz