Changeable weather for most of the country

Thunder and lighting may be in store for some areas. Photo / Herald on Sunday

A changeable week is on the way this week across much of the country with settled weather for some and wet, windy, weather for others.

A large high is forming in the Tasman Sea and should start to spread settled (and drier) conditions over most of the North Island. In the South Island the pressure gradient will remain a little steep between that high and deep lows to the south, so a windy few days are on the way. Nothing too strong, but perhaps 'unpleasant'.

So what weather extremes are we in for this week?

Well it may start this afternoon - as a cold change develops in the South Island it may trigger some thunderstorms over coastal Canterbury and Otago. MetService says there's a moderate risk of this happening along with hail and winds up to 90km/h. You can watch the live lightning tracker here (http://www.weatherwatch.co.nz/content/lightning-radar)

Yep, we have a cold snap on the way - it's not severe but it's going to be chilly. It arrives tomorrow for most of us and in fact some places, particularly those exposed to southerlies, will have a miserable day tomorrow as that southerly kicks in. Masterton is going to spend most of the day in single digits while many other centres will fail to reach teens right up the country.

And if your day time high isn't especially spectacular tomorrow you can bet your bottom dollar that tomorrow night and Wednesday morning will be pretty cold. In fact, if it wasn't for a slight wind I'd say we're heading back in to frosts again. If you do have grape vines I'd keep a close eye on the temperatures overnight tomorrow and into Wednesday as the mercury is likely to fall to near zero in many places south of about South Waikato...light frosts are definitely possible in sheltered places.

The good news? The warmth will quickly come back on Wednesday. It won't be tropical but 17 sounds a lot better than 13, 12 or 10.

Obviously if things are warming up on Wednesday it's due to a shift in the wind. That's most likely to be a nor'wester in the south and that means another front is on the way. MetService has moderate confidence of heavy rain across Wednesday and Thursday along the West Coast which may mean a showery Thursday or Friday for the North Island's west - although latest computer models show high pressure over the area so that's a good sign if you're not wanting anymore rain.

So that's about it for New Zealand. Just quickly overseas and apart from the balloon boy fiasco in America (I laughed so hard at that...what a mental family...it really did feel like one of those "only in America" moments), well apart from that there is a big development in the skies near America - actually this one is closer to Mexico.

A monster Category 5 hurricane, named Rick, is heading towards Mexico and this is one of the most powerful hurricanes you will ever see in this part of the world - normally hurricanes of this size don't form here. Now while Rick is likely to weaken to a Category 2 storm that is still very significant and could cause massive seas and big mud slides and flooding. Rick currently has winds gusting to near 310km/h - faster than the cars at
Mt Panorama in Bathurst last week.

Meanwhile Super Typhoon Lupit is about to pound the Philippines. Boy they're getting a hammering at the moment - rain storm after rainstorm. And while severe gales will slam into the north it's the rain that is more of a worry - up to 500mm of rain is predicted.

Both of these storms are impacting nations that don't have especially strong infrastructure - I think we'll hear more about these to tropical storms
in the coming days.

- Philip Duncan




Photo: Lightning and thunder are possible for some areas. Photo / Herald on Sunday