NZ Weather Forum

From The Press, 23/8/06
"Weather forecasters are warning of more polar outbreaks over the next few months.
While spring may officially be just around the corner, it seems South Islanders should not expect immediate relief from the southerly spells that have brought snow to low levels several times this winter.

Blue Skies Weather and Climate Services director Tony Trewinnard said he had no reason to assume yesterday's cold snap would be the last of the winter.

"But there's every reason to say we will see them for the rest of the year."

Trewinnard said it appeared an El Nino event, which generally brings more west-to-southwesterly winds, was now developing.

The broad weather pattern was conducive to low-pressure systems (depressions) developing as they moved across and out to the east of the country, bringing southerly outbreaks.

MetService spokesman Bob McDavitt said the next couple of months would probably see depressions deepening as they crossed the Chatham Islands area, bringing "brief blasts of polar-chilled southerlies" up the east coast of the South Island.

He warned the threat of thunderstorms and hail in Canterbury may also increase in the next month or so, fuelled by the contrast between warming land temperatures and colder-than-average sea-surface temperatures. "

What are your thoughts on this please.

My thoughts are very obvious!!! It would be rather silly to think that we wont see any more periods of cold southerlies this year, but with the change in seasons I would be surprised if we saw any more as cold as those in the last few weeks. Cold southerlies in spring and summer are usually nowhere near as cold as in winter. I'm not so sure on the thunderstorm bit - IMHO the best pattern for thunderstorms in Canty is from persistent westerlies with regular cold fronts and southwest changes, which hasnt really been the pattern so far. Southerlies dont bring thunderstorms, southwesterlies do. Oh, and Paul got the wrong idea of what I was saying about El Nino, there is no expectation that one will develop.

I have edited your post to include a reference to where this came from. Please dont cut and paste anything from anywhere else without including a reference or acknowledgement. That way we are all clear as to what are your words, and which belong to someone else. Alternatively you can paste the URL link to the article. I also changed the title of this thread from capitals to lower case - we dont encourage shouting here!

[quote="TonyT"]My thoughts are very obvious!!! It would be rather silly to think that we wont see any more periods of cold southerlies this year, but with the change in seasons I would be surprised if we saw any more as cold as those in the last few weeks. Cold southerlies in spring and summer are usually nowhere near as cold as in winter.

The snow we had on the 19 September 2005 was quite unexpected and as far as I can remember not very well forcasted. I realise that every now and then events like these sneak up on us so to speak. What do you think our chances are of having another dump like that this year?

see http://www.weatherforum.org.nz/forum/vi ... php?t=1495

It was actually quite well forecaast (perhaps you dont remember the front page of The Press on the Saturday prior, I know I do!).

Events like that can occur in September, and in the distant past have occurred in October and even November I believe (perhaps not in Chch city, but to low levels on the Plains). However, they are not very common outside of the May to August period. One of the good things about living in Chch is that if you are a snow fan, then usually a short trip up the Port Hills or out to Oxford/Darfield etc can usually satisfy your cravings, even if you dont see snow in the city itself.

No idea if that will happen this September, based on the long term odds, I would have to say probably not...

TonyT wrote:see http://www.weatherforum.org.nz/forum/vi ... php?t=1495

It was actually quite well forecaast (perhaps you dont remember the front page of The Press on the Saturday prior, I know I do!).

Maybe the articles in the newspapers after the event have clouded my memory I know a lot of lambs where lost etc.

Yup we are quite fortunate here in Chch, having the opportunity to visit the beautiful surrounding countryside quite easily is a certain bonus of living here especially when it snows.

The article seemed to put more emphasis on the weather patterns for this spring being more erratic than normal, don't know if I read more into it than they intended, but that's the media for you I guess. Can't help I love the snow and hope there's more!

Just noting that the 19th September '05 event directly followed a low which developed off Brisbane, with very strong cyclogenesis, down to 973mb by it got to Hawke's Bay.
It held a lot of moisture too coming down as a northerly, to enable the much drier southerlies/sw to come up more promptly.
That was one action packed weekend!

With indicators of an El Nino developing.. it could be a while before we see an event like that again.. as Eastern Aust. should see an increase in westerlies. That was special.

Roll on another stormy September!

That was one action packed weekend!

With indicators of an El Nino developing.. it could be a while before we see an event like that again.. as Eastern Aust. should see an increase in westerlies. That was special.

Roll on another stormy September!

It sure was a good one!

Now quoting what Tony said further up:

"Oh, and Paul got the wrong idea of what I was saying about El Nino, there is no expectation that one will develop."

What indications (or contra indications) regarding an El Nino are there?

i cant see any proof that El nino is developing yet.

Its complicated.

Basically, some of the indicators are there which we would expect to see if an EN were developing. However, most of the key ones are not. This leads some to speculate that maybe an EN will develop, but there are no clear signs that it is currently doing so.

exactly my thoughts Tony, so why is metservice saying that el nino is developing just because of a few cold snaps??

squid wrote:why is metservice saying that el nino is developing

I'm not aware they were. I was mis-quoted on the subject in the article referred to in this thread.

It all starts with warmer than normal sea temperatures off the northern South American west coast.

http://www.osdpd.noaa.gov/PSB/EPS/SST/d ... 2.2006.gif
It currently shows a weak, developing phase. Much different to last year's.

I don't think anyone knows how long it takes to effect us here in NZ..

Still a big mystery!

Foggy Hamilton wrote:It all starts with warmer than normal sea temperatures off the northern South American west coast.

http://www.osdpd.noaa.gov/PSB/EPS/SST/d ... 2.2006.gif
It currently shows a weak, developing phase. Much different to last year's.

I don't think anyone knows how long it takes to effect us here in NZ..

Still a big mystery!

Just having a look around the net and there seems to be a few other predictions of El Nino returning. Here's a link to just one of them.

http://www.theage.com.au/news/National/ ... 60283.html

Its quite easy to tell,Cold winter just had means a late spring especially in the west and south as the sun gets stronger the southerlies will gradually weaken and be less intense and "flatten out"to SW or W as the cold anticyclones break down by the westerlies

Doesn't look like El Nino either. Usually have a raging WSW pattern with El Nino. Nothing like that so far.

We have a had a run of relatively settled springs in Auckland in the last few years. Hoping we get the same this year. I need sunny dry weather for my work.

Definitely the opposite of last August

NZstorm wrote: We have a had a run of relatively settled springs in Auckland in the last few years. Hoping we get the same this year. I need sunny dry weather for my work.

personaly i think it will be another nutrual season this spring/summer

TonyT wrote:My thoughts are very obvious!!! It would be rather silly to think that we wont see any more periods of cold southerlies this year, but with the change in seasons I would be surprised if we saw any more as cold as those in the last few weeks. Cold southerlies in spring and summer are usually nowhere near as cold as in winter. I'm not so sure on the thunderstorm bit - IMHO the best pattern for thunderstorms in Canty is from persistent westerlies with regular cold fronts and southwest changes, which hasnt really been the pattern so far. Southerlies dont bring thunderstorms, southwesterlies do. Oh, and Paul got the wrong idea of what I was saying about El Nino, there is no expectation that one will develop.

Yes Tony/Snowlover and everyone else who saw this artice.
I sort of went when I read the thunderstorm bit and I agree with Tony that spring/summer thunderstorm development is to with a more SW regime rather than from a cold southerly outburst from say a depression spinning away to the east of NZ of which these cold weather events have been coming from.
....but then if we are going to continually get periods of cold weather coming up from the south/ice, then the mixture of the cold air over the gradually warming days of the next few months should, and I hope, enhance instability and isolated thunderstorms could develop with hail unfortunately.
I say hail, unfortunately because I consider the growers and fruiterers who's crops are damaged by such events.
Current weather patterns don't suggest a El Nino event although the SOI has been favouring a EN over the past couple of months.



JohnGaul
NZTS

[quote="TonyT"]see http://www.weatherforum.org.nz/forum/vi ... php?t=1495

It was actually quite well forecaast (perhaps you dont remember the front page of The Press on the Saturday prior, I know I do!).

Just read that thread, Tony... Laughing my head off at Gary's cynicism and the humble pie eating once the 19th happened!

Latest info here http://www.bom.gov.au/climate/enso/ makes for interesting reading.

TonyT wrote:Latest info here http://www.bom.gov.au/climate/enso/ makes for interesting reading.

...and keeping the above in mind, here is an interesting read from NIWA:

http://www.niwascience.co.nz/edu/students/faq/enln

Not good news if your farming in the East particularly Canterbury. The very poor winter may be followed soon by drought.