KEY POINTS:
A significant sub-tropical storm is developing Friday and is likely to bring widespread rain across many parts of the North Island along with gales in some areas.
I'll try not to get too detailed in this blog because things will change by Friday evening I'm sure, but this
at least this gives you a basic outline of what to expect this weekend weather wise.
However, I will be updating our special storm page here throughout Friday and the weekend.
Of course Saturday is the last official day of Summer and Summer is going out on a low....quite literally. (Yeah, I've been saving that line up for a while now). The low is being fuelled by a tonne of tropical air - it's wet, it's humid and it's unpredictable. The low itself isn't going to deepen into anything record breaking but the fact that it's pushing up against a high pressure system to the south means winds will pick up as that low deepens.
GALES
Te Aroha, in the eastern Waikato, can expect winds gusting up to 130km/h (my prediction at this stage) in isolated pockets. Those winds are dangerous but to locals they've seen definitely worse. Weak barns, some trees and maybe the odd powerline could suffer as a result. As a former local I can vouch for many poorly built barns in the area - sorry farmers, face facts! Some of the ones I drive past on the Hauraki Plains look like they'll fall over if a newborn calf leans up against them. But I digress - expect strong winds here so be prepared.
As I said on Wednesday, areas close to the ranges from Taihape to Palmerston North and down to Kapiti are also likely to see gales. Trees are especially vulnerable in this region as the prevailing westerly causes them to grow on an angle. Easterly gales don't even have to be severe to break branches - especially with summer leaves weighing the branches down even more.
MetService rates the chances of gales in this area as "moderate" while eastern Waikato has a "high" risk.
Winds are likely to gust over 100km/h in eastern parts of Northland and around Auckland for a time too during Saturday - especially eastern areas and the Harbour Bridge. Take care if you're driving a high-sided vehicle or motorbike. I know that sounds silly but people do actually get blown off roads in gusts.
RAIN
Heavy rain warnings are likely to pop up all over the place for the North Island. When writing this blog on Thursday night warnings were already in place for Northland. I expect to see heavy rain warnings for Coromandel Peninsula, Bay of Plenty, East Cape and possibly Auckland, Waikato, Gisborne, Hawkes Bay, Central Plateau and Marlborough. These are the areas that, in my view, look most vulnerable to this low.
FLOODING & SLIPS
Due to the large high south and east of New Zealand, which will slow the movement of this system down, the risks for serious flooding will be in Northland, Coromandel and Bay of Plenty at this stage. Minor flooding and surface flooding are most likely in Auckland, Gisborne and Hawkes Bay - however this may change as we head into the weekend. Slips are most likely across Northland, East Cape and Hawkes Bay. If you're driving in these regions take extreme care during Saturday and Sunday. Also a risk of some flooding in the Waikato, depending on the angle of this low as it comes in. Again, another thing to watch out for.
MARINE
The low will create rough seas in Northern New Zealand, especially the east, starting Friday in the Far North and moving southwards to reach Auckland either by late Friday or early Saturday. I advise people to at least stay off the seas on Saturday as this storm peaks in the area. On Sunday, gusty north west or westerly winds may return.
Here are some useful links for this particular sub-tropical storm:
- Our special weather news page on this low: (http://www.weatherwatch.co.nz/content/another-sub-tropical-storm)
- The latest Herald weather forecasts and weather maps for NZ (http://www.nzherald.co.nz/weather/news/headlines.cfm?c_id=10&weathersection=regional)
- Road conditions (www.timesavertraffic.co.nz)
- Current official Weather Warnings (http://www.newstalkzb.co.nz/weather.asp?wxregion=&menu=5&menuitem=2)
Top photo: Summer is just about over - time for the rain! Photo / Herald on Sunday