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#246387 - 28/07/2002 15:47 Re: large southern ocean swell
thermalben Offline
Weather Freak

Registered: 17/04/2001
Posts: 769
Loc: Tweed Coast
This swell event is now abating in WA; Margaret River is reported to be in the 6-8' range by SRO and 6-10' by Surfalert. The Cape Naturaliste buoy has been offline since last Friday, but the trend across all other buoys has been of a steady decline since its peak on Friday.

SA still has plenty of action, with the Mid Coast still reporting surf around the head high mark. The southerly wind change is creating bumpy conditions, and a further small increase along the South Coast is expected later tomorrow courtesy of a deep low passing well to the south of the continent.

VIC is displaying small clean surf around 3' in the Bells area, and 6-8' lines at Rye back beach (as reported on surfshop.com.au). The aforementioned swell increase is a little behind schedule, but I'm still confident of a notable increase tomorrow. The wind speeds associated with a deep low south of the continent have been very favourable over the last 48hrs; up around 35-45kts. With some luck this new swell will move into the Bass Strait region overnight or early tomorrow, and with local winds generally light and variable we should see some excellent medium sized surf at Bells Beach - possibly up to 6' *holds breath* laugh

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#246388 - 29/07/2002 10:20 Re: large southern ocean swell
thermalben Offline
Weather Freak

Registered: 17/04/2001
Posts: 769
Loc: Tweed Coast
WA still backing off slowly; around 4-6' as reported by SRO (5-7' by Surfalert).

SA is receiving another long range groundswell with glassy surf arounf the head high mark at the Mid Coast, and overhead conditions on the South Coast.

Interestingly Vic is reporting conflicting reports - the Rye back beach report is calling a dropping swell from yesterday to 5', while the Bells area has reported surf around 4' and increasing in size - I think we'll see that additional swell mentioned above (which is hitting the SA coast at the moment) arrive later today.

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#246389 - 29/07/2002 10:56 Re: large southern ocean swell
liz Offline
Wind Speed Queen

Registered: 02/12/2001
Posts: 1920
Loc: Near Victor Harbor S.A.
Hi thermalben, thank you for the newsy bits as above etc. I must admit that I am now taking more notice of the waves etc, along this part of the South Coast and relate to your postings. I used to live at Middleton, and I guess I just took great surf etc for granted. Liz.

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#246390 - 30/07/2002 10:14 Re: large southern ocean swell
thermalben Offline
Weather Freak

Registered: 17/04/2001
Posts: 769
Loc: Tweed Coast
It seems WA is on it's last legs of this swell event - reported to be in the 3-4' range and wind affected from 20kt westerlies.

SA is still producing excellent surf; the 'second round' which infiltrated the gulf yesterday is still lingering with shoulder high glassy surf along the Mid Coast, and head high to overhead surf (depending on location) along the South Coast with light variable winds.

Vic's swell increase (mentioned previously in this thread) obviously hit either late yesterday or late last night, and has been reported at surfshop.com.au as 3-5' in the Torquay area and 6-8' at Rye Back Beach. Light offshore winds are creating excellent surface conditions. I imagine there'd be some hefty surf along the far western coastline (Pt Campbell) around 10' or so. Interesting for hindcasting purposes too as this additional long-range groundswell wasn't picked up very well by the models in Vic, but was so in WA and SA.

All in all, quite a memorable swell event where it seems almost every region along the southern Australian coastline scored some quality!

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#246391 - 30/07/2002 10:23 Re: large southern ocean swell
Thunderstruck Offline
Lightning man

Registered: 10/05/2001
Posts: 15024
Loc: Seaford Meadows, SA
Damn being back at uni!!!! grrr perfect calm conditions with glassy 4' waves on the Mid!!! God dammitt ill go nuts... mad any chance of a repeat for the weekend??

TS cool

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#246392 - 30/07/2002 16:04 Re: large southern ocean swell
liz Offline
Wind Speed Queen

Registered: 02/12/2001
Posts: 1920
Loc: Near Victor Harbor S.A.
Lennie, Middleton was just great today, you could have surfed with the whales. Liz.

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#246393 - 30/07/2002 18:49 Re: large southern ocean swell
Alex Zadnik Offline
Weather Freak

Registered: 13/11/2001
Posts: 152
Loc: VIC
Hi Ben,
Sounds like you got some quality waves. How do you assess your own forecast over the weekend period. It looks like you got the timing spot on for the first swell. Was there anything that suprised you during the swell event (unexpected increases/decreases in size, direction of swells)? If so, does this have a bearing on your opinion of different models? (I always find wave models a bit misleading, and tend to base swell forecasts on MSLP charts and rule of thumb/past experience).
Look forward to hearing your thoughts,
Alex

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#246394 - 30/07/2002 23:33 Re: large southern ocean swell
thermalben Offline
Weather Freak

Registered: 17/04/2001
Posts: 769
Loc: Tweed Coast
Hey Alex

I'm actually really happy with my forecasting of the weekend's swell event with regards to SA. I haven't had much of a chance to regularly forecast outside of the state, and as a consequence it's been a good learning curve, but on the whole I don't think I did too badly.
Quote:
How do you assess your own forecast over the weekend period
This is one of the hardest parts of verification. You can't argue with a thermometer - if it's 16 degrees it's 16 degrees, despite the fact that your body is telling you it's much colder! But surf size is an interesting issue (brought up many times before...)
One person's 6ft is another person's 10ft and a third person's 4ft. So it can be hard to know where to get your info from and who to trust. But for my own verification I use cams, buoy data, and reports posted through a variety of sources on the internet. I archive most of this info so that I can recall it for hindcasting purposes, and also to assess against archived model data. As swell models are quite 'broadscale' in application, it's hard to fine-tune their output for a particular area. But over time I have found that I continually learn from experience - mistakes can be a good tool in this regard.

Quote:
It looks like you got the timing spot on for the first swell
thanks! I got some great feedback in SA on the timing of the swell (also managed to experience it myself...he he); it's quite hard to sit at the beach having checked the sat. wind data and knowing the swell's not far off...agonizing infact!
Quote:
anything that suprised you during the swell event
Definitely! I learn something new every day - I suppose that's what keep me so interested in marine forecasting. Out of this event, the first few days (Thurs/Fri/Sat) generally went as forecast. However the swell abated in certain areas prone top more SW direction (SA south coast; Vic) during the middle of the weekend, and the 'second round' of swell I forecasted for these areas for Monday were both a touch smaller and later than anticipated. I am now quite aware of why this occured, but at the time the model data indicated something more substantial (I also got rather busy towards the end of the week, reducing my analysis time...). This has more to do with swell directions Vs Map projection - worthy of another thread in itself - and also my regular verification tools don't quite cover the areas I'd like them to sometimes...
Quote:
does this have a bearing on your opinion of different models?
IMHO, you can't beat experience. Swell forecasting is one of those disciplines that will always be hard to get a feel for unless you participate in activities based around their outcomes. It's one thing to dial up a few charts and estimate wave hieghts, and another to be at the beach and observe chest high groundswell at 18 seconds - comparing it to the chest high windswell you surfed the previous weekend inside Port Phillip Bay.

Anyway thanks for the nice words; hopefully we will have something more to write about behind this weekend's interesting weather system! I'm also testing a long range Indo forecast on a thread on ski.com.au - will be interesting to see how that one goes too. Indo is an interesting region, and first hand verification will be good to have!

Cheers, Ben

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