KEY POINTS:
A deep low is predicted to develop out in the Tasman Sea during Friday and Saturday and there's concern that heavy rain may well move in to places already affected by July's big drenching.
The low is going to move over New South Wales and out into the Tasman Sea then rapidly deepen during Saturday. By Saturday night the pressure gradient between the low and a large high north east of New Zealand will mean northerly winds will pick up considerably in some exposed areas.
The low is moving from west to east, which is different to the big low in late July which moved in the unusual direction of North East to South West. This means a repeat of late July's flooding s is quite unlikely. However flooding is still a possibility because the ground is saturated - localised pockets of minor to moderate flooding may be possible in low lying, sodden areas.
The main rain band will be moving in over the North Island late on Saturday and into Sunday. Heavy rain is likely in Nelson, Taranaki, and other north facing regions such as Bay of Plenty, Coromandel and Northland.
The extra rain won't be welcome news to farmers in the middle of calving and lambing. Waikato farms have seen some huge rainfall figures - some in the eastern areas have had half of their annual rainfall in just one month. Some in the western Waikato are possibly going to see the wettest 3 months on record.
It's been a tough year for farmers in this area - and of course other parts of New Zealand - struggling with droughts then floods. We can only hope that Spring sees a return to normality - my gut instinct says it will.
I said on TVNZ's Breakfast show back in April that drought affected farmers in the Waikato and other northern areas should be prepared to go from droughts to floods - that was based on gut instinct and the fact that waters around New Zealand were slightly warmer - warmer waters usually fuel more lows.
It's starting to sound like a broken record but Aucklanders will again see a wet weekend. Showers turning to rain late Saturday. Showers on Sunday and some could be heavy. Monday doesn't look much better either. Cold sou'westers will roll back in early next week too. This is winter after all though.
But, even when the weather seems uttlerly depressing to some, it can be positive to others. The silver lining with this system is that starting today and lasting until Monday is that it will be considerably warmer over northern New Zealand.
Okay, it might not be tropical but the air is actually being sucked down from the sub-tropics. In Auckland the overnight lows are going to be around twice as high as they were last week with Friday and Saturday night both dipping to around 12 or 13. Highs will be up in the late teens today and tomorrow too. So it's probably going to feel very spring-like over northern New Zealand this weekend.
If you're itching to get out and make the most of the huge snow base on Mt Ruapehu there appears to be a good window next week. In fact, there's a large pool of settled high air pressure which looks as though it may drift over the country mid way through next week.
It's still a little too far out to be sure but I think it's looking more likely than less likely! So fingers crossed for that one - some regions may have quite a few sunny, dry, days on the way. I'll give you more details on Monday!
Have a great weekend.
Philip Duncan
Pictured above: Heavy rain causes huge rapids over McLarens Falls this week. Photo / Mark McKeown, Bay of Plenty Times
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