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#246367 - 22/07/2002 20:53 large southern ocean swell
thermalben Offline
Weather Freak

Registered: 17/04/2001
Posts: 769
Loc: Tweed Coast
Hmmm...this area of the db is about as inactive as it can get!...'tis a shame, really...

Anyway there's a very nice series of weather systems bearing down on the southern Australian coastline which should produce sizeable surf in WA and SA (and hopefully Vic) from later this week through the weekend and into next week. MRF in particular is forecasting a series of lows to form within the LWT which should blanket us with excellent surf. Favourable local wind conditions are also quite likely throughout the period.

WA should see some action appear during Thursday, and SA later Friday with a secondary low pushing swell into Vic for the latter part of the weekend and through 'till the following week. I've posted a slightly more indepth discussion on Swellnet (in relation to SA, anyway).

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#246368 - 22/07/2002 23:22 Re: large southern ocean swell
Adiabatic Offline
Member

Registered: 01/09/2001
Posts: 14190
Loc: Knoxfield 96m: 120.2mm
Sorry thermalben,

I dont know if you have answered this in another thread, and I am too lazy to find it, but are you contemplating extending your swell forecasts and discussions to VIC by any chance? They are really good, one of the best discussions I have seen.

Looking forward to the winter swells returning, well some of it anyway smile

:cheers:

Karl smile

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#246369 - 23/07/2002 11:17 Re: large southern ocean swell
Thunderstruck Offline
Lightning man

Registered: 10/05/2001
Posts: 15024
Loc: Seaford Meadows, SA
It sure is a good site!!!! Love ur forecasts Ben!!!

It is looking great as well and im free this weekend...then its uni next week so im def going to the South Coast on sat and sun.

TS cool

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#246370 - 23/07/2002 14:24 Re: large southern ocean swell
thermalben Offline
Weather Freak

Registered: 17/04/2001
Posts: 769
Loc: Tweed Coast
Hi Karl,
Quote:

but are you contemplating extending your swell forecasts and discussions to VIC
Thanks for the kind words. In short, yes I will be expanding, first to Victoria but hopefully nationally aswell. At the moment it's just a time issue to me (and $$!) - I have no interest in providing a service that is second rate. That's why I have kept it local for the last 12 months - it's been a good way to assess the forecasts and get some local feedback. However it appears that there's a pretty high demand for a detailed forecast of this nature, and I'm working on something more 'broadscale'.

Everything still on track for this swell at the moment, looking very nice indeed. Hopefully I'll do a report tonight (I'll be on the road tomorrow) which will update the current situation.
Also, a nice small unrelated swell event moved into the SA region last night (around 3m @ 17secs, but period dropping quickly) producing very straight surf around head high at Middleton today and small 1-2ft surf at the Mid Coast.

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#246371 - 23/07/2002 14:31 Re: large southern ocean swell
liz Offline
Wind Speed Queen

Registered: 02/12/2001
Posts: 1920
Loc: Near Victor Harbor S.A.
Hi Thermalben, Day street and Middleton looked great today couldn't help admiring them when driving back from Goolwa. Even the chicken run looked good again. Where the whales are at Bashams, there was a swell coming in and ended perfectly, but too close to rocks. Liz.

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#246372 - 23/07/2002 15:37 Re: large southern ocean swell
thermalben Offline
Weather Freak

Registered: 17/04/2001
Posts: 769
Loc: Tweed Coast
Thanks Liz, it looks quite nice down there today (judging by the surf cams, anyway). This swell will slowly fade over the next few days, and there will be some prime whale watching weather with light winds and a small swell. However the weekend might see them heading for shelter....I hope anyway! (with all due respect to the whales, but the surf's been a little on the 'small' side this winter at Victor... laugh )

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#246373 - 23/07/2002 16:06 Re: large southern ocean swell
Alex Zadnik Offline
Weather Freak

Registered: 13/11/2001
Posts: 152
Loc: VIC
Hey Ben,
Look forward to hearing how you guys go with swell. As you said, looks like swell will start arriving Thursday. Looking at GASP it looks like you may get some great conditions early on Saturday (another pulse of big swell) before the SW change (EC and MRF kind of agrees too). What are your thoughts? and what models do you usually use?
Also another question, are the spots you forecast for somewhat sheltered from swell, it seems like when there is a big swell on the way you keep the forecast range fairly low (4ft or so). Not having surfed in SA I thought this may be the reason.
One last thing, looks like well get a low develop in the Tasman during Wednesday night, so could be some nice waves about NSW late Thursday and early friday when the southerly winds abate (probably 4-6ft).
Anyway back to work for me, happy surfing all.......
Alex
PS Look forward to you surf forcasts for VIC Ben, your current site is excellent, keep up the good work!

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#246374 - 23/07/2002 18:11 Re: large southern ocean swell
thermalben Offline
Weather Freak

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

Cheers for the nice words smile
Quote:
As you said, looks like swell will start arriving Thursday. Looking at GASP it looks like you may get some great conditions early on Saturday (another pulse of big swell) before the SW change
(assuming you are talking about SA here...) yes, there's several swells likely to be associated with this 'event'. Most of the initial swell appears likely to arrive in SA late Thursday, but as long range groundswell with only little size. The good stuff (ie a bit o' size) will follow through on Friday, but it's most likely to be quite westerly in direction, so as far as SA's most accessible beaches are concerned, the Mid Coast (west facing, inside the Gulf St Vincent) will benefit Friday, while the South Coast (the south facing beaches surrounding Victor Harbor, in the lee of Kangaroo Island) will benefit later in the weekend as a few short wave troughs spin off the main low whipping up some more swell (progged by the latest MRF run, anyway!)
Quote:
and what models do you usually use?
Unfortunately the best swell models available are driven by NOGAPS, which I'm not too enthusiastic about in winter. The LAPS swell model uses increments of 1m - too much room for error IMO, and ill defined for serious swell forecasting (but quite OK I suppose for oceanic marine forecasting purposes). Generally though, I prefer AVN/MRF, and cross-check this against the external ECMWF and UK data available. Also, I compare these models vs NOGAPS; as NGP forces the wave model, it's easier to spot inconsistencies with wave height outlooks past a few days.
Quote:
are the spots you forecast for somewhat sheltered from swell
Yes, incredibly so. The Mid Coast (30kms from Adelaide) suffers extensively from wave refraction and friction due to its location in the Gulf St Vincent. This occurs on a smaller scale at Victor Harbor (on the South Coast), although a more S swell can do wonders for reef breaks located close to the township. However, as the predominant direction is SW in SA, the largest swell energies are usually aimed towards the Coorong!

Anyway it's been a great learning curve, hopefully the Vic forecasts will be well received too.

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#246375 - 23/07/2002 19:02 Re: large southern ocean swell
Alex Zadnik Offline
Weather Freak

Registered: 13/11/2001
Posts: 152
Loc: VIC
[img]http://www.surfshop.com.au/ryebackbeach/surf[/img]
Hey Ben,
If you want any info on local VIC surf spots I can provide. Here is a nice shot of todays surf on the Peninsula(photo courtesy of www.surfshop.com.au).
Alex

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#246376 - 23/07/2002 19:05 Re: large southern ocean swell
Alex Zadnik Offline
Weather Freak

Registered: 13/11/2001
Posts: 152
Loc: VIC
By the way the size in the pic is 6-8ft. Spoke to a victorian friend today who said the wind swung nor'west early in the day, but if there were any banks holding it early on it would have been siiiiiiiick!
Low tide was a'noon so none of the well known Flinders spots would have been that great.

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#246377 - 23/07/2002 19:52 Re: large southern ocean swell
thermalben Offline
Weather Freak

Registered: 17/04/2001
Posts: 769
Loc: Tweed Coast
Looks are deceptive! 6-8'? Wow...I must admit I haven't done much exploring east of Melbourne (but will sometime in the future).

I have found surfshop's site to be pretty annoying at times - besides the dated web page layout, most of the reports are not filed regularly (the hassles of volunteer info, I suppose!). However they do provide nice digital pictures at times, like the one above...it's just such an underserviced area considering the diversity of surf and marine activities in Victoria. Compare it to realsurf.com which has 10-15 reports for NSW... hmmm. And the lack of beach cams in Vic compared to interstate...

Anyway just one of those things, I suppose. Probably related to population density issues along the coastlines, if nothing else.

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#246378 - 23/07/2002 20:02 Re: large southern ocean swell
Alex Zadnik Offline
Weather Freak

Registered: 13/11/2001
Posts: 152
Loc: VIC
On second thoughts it is probably about 5ft in the shot (but pretty solid). The Peninsula blokes tend to over estimate (IMO). East of melbourne is definitely worth a look too.........

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#246379 - 24/07/2002 16:33 Re: large southern ocean swell
Alex Zadnik Offline
Weather Freak

Registered: 13/11/2001
Posts: 152
Loc: VIC
Thought that might happen with the picture, it's going to update everytime they put a new shot on the site! Looks pretty average there today.

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#246380 - 25/07/2002 14:27 Re: large southern ocean swell
thermalben Offline
Weather Freak

Registered: 17/04/2001
Posts: 769
Loc: Tweed Coast
OK, just back on topic a little...

WA is receiving the first part of this swell system. Buoy readings are around 4m @ 12 secs, but I imagine the peak period will rise a little throughout the course of the next day or so (as will the height - in a major way!). The surf was reported on SRO and Surfalert as in the 10-12ft mark (ie very large), but this will surely rise up into the 15-18ft+ surf size by Friday and into Saturday.

It's absolutely flat here in SA, however buoy readings are 2m @ 13secs (obviously quite a lot of local wind swell in those figures as N winds have been up around 20-30kts over the last 12 hours or so). We should start to see peak wave periods jump up around 16 seconds by early tomorrow, and the surf should start building during the afternoon along the Mid Coast. However a succession of further swell events are behind this and will ensure excellent waves in SA until next Tuesday atleast. The South Coast in particular will benefit from a more SSW swell around 5-6ft later Sunday/Monday with light variable winds.

Vic is looking quite interesting; with the first intial swell moving into their region Sat and Sun we should see a small increase in size in the Bells region to around 3-4ft. However MRF is progging a very tasty low to move beneath the continent over the weekend, and any swell that is generated from this looks like it will be much more favourable in direction. At this stage it's looking very nice for surf in the 6-8ft range at Bells for Monday, with light variable winds. Although a stiff NW offshore wind is preferable to straighten out the lines a little, I don't think there will be many complaints in the Torquay region early next week!

Actually I don't want hear any complaints from anyone along the Southern Ocean; this has been one of the best autumn/winter combos I have seen in a long while! laugh

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#246381 - 25/07/2002 22:49 Re: large southern ocean swell
Adiabatic Offline
Member

Registered: 01/09/2001
Posts: 14190
Loc: Knoxfield 96m: 120.2mm
Hi Alex,

Its great to know what I am missing while I am at school. Looks like its been a mad week of surf smile

Karl smile

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#246382 - 26/07/2002 14:55 Re: large southern ocean swell
thermalben Offline
Weather Freak

Registered: 17/04/2001
Posts: 769
Loc: Tweed Coast
OK! Good new all round for SA. We are receiving the first few signs of the new swell (as mentioned last Thursday ). Unfortunately the CdC buoy has been offline since 4:30am, but the Mid Coast is displaying sets around chest to shoulder high and with an nicely sized incoming tide this afternoon there will be excellent waves along the reef breaks (also partly because quite a few people checked it this morning and wrote it off! So there won't be much of a crowd...he he).

The swell's westerly trajectory is the reason why it's not affecting the Victor Harbor region. However tomorrow will be more prosperous for a swell increase in this area, and offshore winds will ensure good conditions.

WA is still huge and out of control with SRO reporting 12-15ft surf. Very windy and choppy though (apart from the protected bays and points).

And Vic is dead flat as expected. It won't pick up significantly 'till later in the weekend.

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#246383 - 26/07/2002 15:38 Re: large southern ocean swell
Adiabatic Offline
Member

Registered: 01/09/2001
Posts: 14190
Loc: Knoxfield 96m: 120.2mm
What are you tipping for swells after the wind change comes through? Would 4ft be a reasonable estimate along the exposed coastline?

Karl smile

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#246384 - 27/07/2002 12:03 Re: large southern ocean swell
thermalben Offline
Weather Freak

Registered: 17/04/2001
Posts: 769
Loc: Tweed Coast
Karl, I think the Vic coastline will get surf well above 4' (depending where you are - it's 4-5' at Rye back beach today)...but it's still developing in size as we speak. I usually refer to the Bells Beach side.

WA is still very large - around 12-15' as reported by SRO (15-20' reported by Surfalert). Winds are most favourable for the protected bays and points again.

SA is developing nicely along both coasts. The surf came up as forecasted along the Mid Coast last night, with sets around head high along the Mid Coast reef breaks (even small clean waves further up St Vincents Gulf at a few unnamed locations...). The South Coast is now picking up as the swell trajectory tends more SSW, and with surf already around the head high mark at Middleton, this should improve all weekend.

Vic is also feeling the first few pulses of the new swell, with Rye around 4-5' and Bells around 2-3'. This will however pick up during the day, and I wouldn't be surprised to see surf around 4-5' at Bells by dusk tonight. The rest of the weekend will no doubt display some excellent waves.

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#246385 - 27/07/2002 14:04 Re: large southern ocean swell
thermalben Offline
Weather Freak

Registered: 17/04/2001
Posts: 769
Loc: Tweed Coast
Grrrrrrrr...
I can't believe that the CdC buoy has been offline from early Friday morning - just on the eve of this swell event in SA! I really find it useful to correlate the realtime data against the beach visuals. They don't always match up, but it's one piece of the puzzle.

Perhaps the BoM can drop by to fix the buoy on their way to Neptune Island to fix the broken anemometer! laugh

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#246386 - 27/07/2002 23:45 Re: large southern ocean swell
Adiabatic Offline
Member

Registered: 01/09/2001
Posts: 14190
Loc: Knoxfield 96m: 120.2mm
Thanks for your input thermalben smile :cheers:

My cousin down on Phillip Island is reporting steady increase in swells, from 4ft yesterday evening increasing to 5-6ft this afternoon. Could it get bigger? We shall wait and see, but certainly it would have been packed on the beaches in this rare warmth in winter.

Karl smile

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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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