Column by Philip Duncan — On Saturday WeatherWatch.co.nz briefly mentioned at the end of a story the possibility of a new sub-tropical low for northern New Zealand in the second week of April.

Today the models are still indicating this is possible, but being so far out – and with the weather so fickle for many – we don’t want to make any big calls just yet – simply bringing it to your attention.

As we’ve been doing all year we track the computer models – the same ones used by weather forecasters all over the globe – and we give you our predictions on what we think is most likely to happen. 

Computer models can be hugely helpful – but if you put all your…eggs…in one basket (that just happened, I didn’t plan that line I swear!) then you’re setting up for a big fail.

I’ve seen computer models show major tropical storms that not only didn’t hit us – they never formed in the first place.  However the miss rate from these international computer models is getting less and less. Those that spend many hours a day looking at this data and these models (like we do at WeatherWatch.co.nz – and we know some of you do too) then you start to see patterns and when something looks right or wrong.

At the moment there are signs that a low may form around northern New Zealand at some stage in the second week of April – between April 8 and 13.

Our confidence of this bringing rain to New Zealand is about 30% today.  It was 20% on Saturday.   If this low does eventuate it could bring more rain to the North Island.

We hope to update you again around Wednesday on this particular possible low.

WeatherWatch.co.nz is still contracted to provide rain reports to the New Zealand Government via the Ministry for Primary Industries – we hope this week to give them some positive news, but need a couple more days  to lift our confidence levels above the current 30%.

At 30% confidence it’s possible this entire low may fail to affect New Zealand – so it’s important those who need rain keep this in mind too, to limit false hope.

– Image / File, Sue Louis

– Column by head weather analyst Philip Duncan