Weather Watch: Waiting for the rain

When is it going to rain? Photo / Hawke's Bay Today

I'm starting to get asked more and more "When is it going to rain?". In Taranaki water restrictions have started to come in to force and there are talks of Northland following suit.

The worrying factor is just how early the dry weather has kicked in. Those in Northland are still haunted by the memories of the costly drought that hit last summer - and some are drawing comparisons to the dry start to the season this year.

There is a difference between this year and last. This year we have La Nina which increases the risk of sub-tropical lows coming down our way.

But as I've said numerous times before La Nina and El Nino patterns have a generic affect to New Zealand but because we are so small one long lasting anitcyclone can see "typical" La Nina conditions go out the window. For islands like New Zealand we can be comforted by the elevated chances of rain in the north this summer but we really can't rely on it - simply because we are so small.

I've been closely watching the tropics north of us to see any development - and to be honest it's been fairly quiet so far. However in the past two days there has been some predictions of a sub-tropical low in about 10 days time.

On Monday the long range maps I use showed no tropical development. On Tuesday the 10 day maps showed a tropical storm or cyclone. By today, Wednesday, the maps had met half way with a sub-tropical low instead. The next few days will be critical but there is certainly a lot of high pressure north of us at the moment which stops these lows from forming.

This low could move down next weekend and affect Northland and East Cape. But it is very early days. I don't want to give false hope but I guess my message is don't let the current weather set up make you think this summer is a repeat of last summer - its make up is quite different weatherwise.

But at the end of the day it's all down to the weather systems, the highs and lows, that move past our dot of a nation.

The prediction from NIWA, which is supported by weather organisations around the globe, calls for an average to above average rainfall this summer in the north... so we may just have to wait a few weeks longer if this low next week doesn't eventuate.