NZ Weather Forum

Bitterly cold weather could coincide with the arrival of spring in a fortnight, bringing bad news for farmers.

The southern annular mode (Sam), which measures the strength of the vortex, has been at record highs in the past month, meaning the polar air has been locked around Antarctica.

However, computer models show Sam is expected to weaken over the next few weeks and return to negative values for the first time since April, allowing polar outbreaks to head north towards New Zealand, Australia, South Africa and South America.

http://www.stuff.co.nz/national/4034277 ... for-spring

I'm glad you brought up SAM
I was going to make a topic of SAM but you bet me to it.
Maybe SAM could be more interesting than El Nino/La Nina as far as forcasting weather projections over a seasonal period?

JohnGaul
NZThS

But really polar outbreaks have not been been locked around Antarctica over winter,wasnt it back in late june/early July that South America received one of the nastiest snows falls for many years that even saw the cold air mass cross the equator??

I'm picking a lot more anticyclones this spring - these southerly outbreaks will have a hard time pushing them out of the way.

Likewise & it suits me fine, Im up to my ears in mud & have had enough of it.

The whole gist of the article I read is there is no expectation that NZ is neccesarily in the firing line- just as likely to be out to sea in the Southern Oceans, or South America.

I wouldn't be running around getting excited yet.

TonyT wrote:I'm picking a lot more anticyclones this spring - these southerly outbreaks will have a hard time pushing them out of the way.

Yep I agree with that... they have just been ballooning over Australia and out into the Tasman all year, stopping those true southerlies.

TonyT wrote:I'm picking a lot more anticyclones this spring - these southerly outbreaks will have a hard time pushing them out of the way.

I hope you right. I'm fed up with the rain and cloud that have dominated here since mid-May.

TonyT wrote:I'm picking a lot more anticyclones this spring - these southerly outbreaks will have a hard time pushing them out of the way.

yer and those anticyclones parked up just to the east of the country would be even better.

Richard wrote:

TonyT wrote:I'm picking a lot more anticyclones this spring - these southerly outbreaks will have a hard time pushing them out of the way.

yer and those anticyclones parked up just to the east of the country would be even better.

Yes, how and where those Anticyclones move is important.
ECMWF shows a High to the SE of NZ for the next week so no Polar blast while that sits there.

early days yet but i see metservice have snow for christchurch on saturday clearing in the afternoon

yes, the gfs is chucking out the cold numbers for the end of the week.

frosty wrote:early days yet but i see metservice have snow for christchurch on saturday clearing in the afternoon

Yes. I have my tennis rackets ready

JohnGul
NZThS

NZ Thunderstorm Soc wrote:

frosty wrote:early days yet but i see metservice have snow for christchurch on saturday clearing in the afternoon

Yes. I have my tennis rackets ready

JohnGul
NZThS

There have been several occasions where the metservice 10 day forecast has predicted snow for ChCh like this in 2010, and its been wrong each time. Presumably its a strictly model based output.

I'm not holding my breath either

NZThS[/b][/color][/quote]
There have been several occasions where the metservice 10 day forecast has predicted snow for ChCh like this in 2010, and its been wrong each time. Presumably its a strictly model based output.

I'm not holding my breath either[/quote]

Precisely, it happens quite often. It must be some sort of default setting that randomly throws things in there. When you go to the rural it would suggest around 500m. May get a little lower but not snow in the city by any stretch of the imagination. If we were to have snow it wouldnt be with light winds either. It would at least say southerlies or something.

Its a shame , because its stuff like that which non-weather enthusiasts (ie normal folk ) look at and lose faith in the forecasts over

Ive noticed if you look ahead that the 10 day forecast has LIGHT WINDS, LIGHT WINDS etc, but when we get closer to the days they change it to stronger winds.
I think its a discrace and a lazyness in forecasting for our country, you dont see CRT doing that ok forecasts change over a 10 day period but theres no need to be lazy about it.

Anyway if we get some heating before the cold blast on Friday afternoon there could be a chance for brief thunderstorms more or so through the foothills and north to Kaikoura.
Abit of overnight brief rain on Thursday but i dont think it will turn true southerly until friday afternoon, and there is that gap between the first front crossing from the NW and the southerly chaser.
I know its only September but look at what we got last week from a weak low out to the east.

Will be interesting to hear/ see what happens this week then.
I am off to gold coast for 5 days so will miss anything if it eventuates but i will come back with any news if anything exciting happens over there!!

Dont worry its back to sunny and light winds now

pack me in your bags please

mikestormchaser wrote:Will be interesting to hear/ see what happens this week then.
I am off to gold coast for 5 days so will miss anything if it eventuates but i will come back with any news if anything exciting happens over there!!

I hope there is some activity over the Tasman this evening as I fly over to Sydney. Sorry Michael

Unfortunately the weather looks boring for the couple of days I'll be there.

I could do with a few "boring" sunny days anyway take some aerial shots.

tgsnoopy wrote:I hope there is some activity over the Tasman this evening as I fly over to Sydney. Sorry Michael

Unfortunately the weather looks boring for the couple of days I'll be there.

yes the Met service has Saturday now with fine and not much wind .

Once again they had teased us ch ch folk with the prospect of snow.

I think there is more chance of low level snow on the Port Hills and Banks Peninsula.After the main band pushes through it looks like a chain shower set up with sleet and snow heading up the coast in the coldest air.