winna. how's it lookin?

[Donweather]

And right on cue, it looks like we might get our first real burst of W/SW winds during the first few days of August.

[Trev]

And right on cue, it looks like we might get our first real burst of W/SW winds during the first few days of August.

Anything coming with it to make it worthwhile, Don?

[oldman]

I always remembered August being mostly onshore... On the east coast anyway.

really?
what about THE august winds. ie the offshore gusts and gales we get for a month straight? .

Yep, August westerlies

[Donweather]

Anything coming with it to make it worthwhile, Don?

Not for SE Qld Trev. Majority of the swell looks to be either hitting the Sth coast of NSW or too west of south to have an impact north of the border (based on current models).

[steve shearer]

Well, the main synoptic feature of this winter so far, has been the lack of strong cold fronts penetrating into the Tasman sea, resulting in a very timid and lacklustre S swell index for NSW.
There is a whole bunch of reasons for this and I suspect, and have reasonable grounds for this, that Global Warming is party responsible.

We're generally seeing am increase in the Tropical Hadley cell which is pushing the sub-tropical high pressure belt slightly but signifcantly further south.
This was one of the main predictions of the result of Global Warming.

This is having the effect of suppressing the lower latitude westerlies from entering the maritime continental landmass, and preventing cold fronts from really firing up into the Tasman.
If you've looked at this winter, the focus of Southern Ocean storm activity has been the central Indian ocean and central South Pacific....resulting in epic surf in WA and Chile/Mexico.
One measure of this is the SAM (Southern Annular Mode), also known as the AAO (Antarctic oscillation). When this is positive, as it has been lately the storm track is generally suppresed towards more southern latitudes.
In the last days we've seen a very rapid decline in the values of the SAM. This now occurs in conjunction with a series of cold fronts entering the Tasman sea from this weekend and a more northwards located high cell.
A big lever has now been shifted as the winter draws to a close.
Be very interesting to note the affect this has on S swell activity in the Tasman sea.

[black duck]

^^^ Sounds like you know what you're talking about

Just checked the SAM data (thanks for the references) and it shows negative numbers for early April and early May this year. Not sure that it translated to any significant south swells for the east coast during that period? I think the Mentawais had a few early season swells that may correspond with the SAM data but my memory is completely unreliable to say the least. Be interesting to correlate the data between swell events and the SAM oscillations.

[Donweather]

Interesting read Steve.

There's some very deep reading in this long winded article also, but in summary, it appears that the AAO influence is more pronounced in La Nina years, compared with El Nino or Neutral years.

http://findarticles.com/p/articles/mi_7 ... ntent;col1

[Donweather]

OK, here goes black duck.

And from the archive data I have access too, looking at the first negative AAO period around 16 April, I note that Sydney saw a small, but very long period S'ly groundswell (1.2m@ 18 seconds)....noting that April is still rather early in the winter swell pattern, so that's still a pretty good swell from the south.

The next AAO negative period was around the early-mid May. Swell archive data is showing a nice 2.5m+ @12 sec S'ly swell hitting Sydney around 16 May.

One major outlier in the above AAO data is for when it was the second largest positive in very early June, Sydney saw a 3m @ 10 sec SE swell (presumbly from a Tasman low) on 31st May.

[black duck]

One major outlier in the above AAO data is for when it was the second largest positive in very early June, Sydney saw a 3m @ 10 sec SE swell (presumbly from a Tasman low) on 31st May.

DonW, that June discrepancy must've been all those butterflies going nuts in the Brazilian rainforest.
The Tasman seems to be a regular rule breaker, never seems to follow all the pointers.

[Kunji]

I always remembered August being mostly onshore... On the east coast anyway.

really?
what about THE august winds. ie the offshore gusts and gales we get for a month straight? .

Yep, August westerlies

Maybe late August. Because i remember the sw winds in the first half of september.

[Trev]

I always remembered August being mostly onshore... On the east coast anyway.

really?
what about THE august winds. ie the offshore gusts and gales we get for a month straight? .

Yep, August westerlies

Maybe late August. Because i remember the sw winds in the first half of september.

Certainly early to mid August up here Coops.

BTW. You're not backpedalling are you??

[Donweather]

Ahhhh.....winter......can't complain up here in SE Qld that's for sure. And how's that winter producing swell on the horizon

[SAsurfa]

I'm thinking along the same lines as you Steve with the sub-tropical high pressure belt protruding further south, keeping the frontal activity further away for the continent and also holding back the fronts moving into the Tasman.

Whether we can see any trend yet or this is just the them for the last winter two is still be seen.

All I've got to say is that I've been here 2 winters and I'm yet to see anything special.

The week coming is looking a little more active so lets hope we see a bit more action across our coast into August and early Spring!

[brendo]

Well, the main synoptic feature of this winter so far, has been the lack of strong cold fronts penetrating into the Tasman sea, resulting in a very timid and lacklustre S swell index for NSW.
There is a whole bunch of reasons for this and I suspect, and have reasonable grounds for this, that Global Warming is party responsible.

We're generally seeing am increase in the Tropical Hadley cell which is pushing the sub-tropical high pressure belt slightly but signifcantly further south.
This was one of the main predictions of the result of Global Warming.

This is having the effect of suppressing the lower latitude westerlies from entering the maritime continental landmass, and preventing cold fronts from really firing up into the Tasman.
If you've looked at this winter, the focus of Southern Ocean storm activity has been the central Indian ocean and central South Pacific....resulting in epic surf in WA and Chile/Mexico.
One measure of this is the SAM (Southern Annular Mode), also known as the AAO (Antarctic oscillation). When this is positive, as it has been lately the storm track is generally suppresed towards more southern latitudes.
In the last days we've seen a very rapid decline in the values of the SAM. This now occurs in conjunction with a series of cold fronts entering the Tasman sea from this weekend and a more northwards located high cell.
A big lever has now been shifted as the winter draws to a close.
Be very interesting to note the affect this has on S swell activity in the Tasman sea.

can you explain if this is result of global warming, why is peru in the grip of its coldest winter in 40yrs.? 2 yrs ago ours mountains had 30+ days of temps below zero in a row. a record...why is it when ever we get a few hotter than normal days ,the experts come out with the global warming lines. but there have been some very cold winters in both hemispheres last few yrs, and we dont hear a word....look at the snow season this yr, shit in a word. but if you look at the records for the last 40 odd yrs, there is no consistency. a couple of good yrs, then shit. but as soon as there is no snow, like this yr, oh, thats global warming..
sorry to go ff topic. please continue

[Topher]

Yep, I've read that the preditced impact of global warming isn't hotter days. It's apparantly much more complicated (and scary) than that.

Flat again today. Wheres the winter love huey?

[steve shearer]

Anyway, this is mostly uncharted waters, so to speak.

I've always had my gaze on the Pacific Basin and trying to understand the various forces and atmospheric/ocean cycles there : ENSO cycles, Walker Circulation, PDO, MJO, WWB's etc etc.
Seems we are in the infancy of relating that to seasonal surf forecasting.....and make no mistake, there is a strong seasonal signal which is useful to understand.

It's only now that I'm looking to the Southern Ocean and trying to understand the mechanisms of the storm track there and how various indices might reflect it.....obviously there is the LWT/polar jet.
If anyone knows any research or even speculation relating to the SAM and frequency/track of southern Ocean/Tasman sea cold fronts/lows I'd love to hear about it.
Cheers, S

[alakaboo]

steve, check out work by matt england and colleagues.
at the climate change research centre, unsw.
http://www.ccrc.unsw.edu.au/staff/academic.html
can chase any papers you're interested in, i have journal access.

[brendo]

the weekend of the 14th aug is lookin interesting....and solid.....