Early Bells forecast: Fine but not all time

Craig Brokensha picture
Craig Brokensha (Craig)
Swellnet Analysis

The biggest swell of the year hit Victoria last Friday and Saturday, breathing life into the Surf Coast reefs that had lain relatively dormant throughout the summer.

Now all eyes are set on the Rip Curl Pro which begins next Tuesday, the 3rd of April. Will we see conditions as epic as last year's 50th anniversary? Or will the event go mobile as happened in 2010 when small swells and bad winds forced the Bell to be rung on the sands of Johanna?

With swell models lighting up across the Southern Ocean in recent days, there's been wild and varying speculation regarding the size of the swell expected in Torquay, ranging from tiny and onshore to big and perfect.

In short there'll be plenty of swell, but not from Bells' ideal direction.

If you've been keeping an eye on our recent articles regarding the link between the Long Wave Trough (LWT) and swell potential across southern Australia you'll be pleased to hear that another 'node' of the LWT is set to move in across the country just in time for the competition.

There's one small issue though: the LWT will be positioned across southern Western Australia during the weekend and early next week. This will result in Southern Ocean storms being aimed up into Western Australia's South West coast with Victoria's Surf Coast seeing unfavourable W/SW swell energy arriving through the first half of the waiting period.

The ideal swell direction for the Surf Coast reefs is between SW-SSW as westerly swells have to refract in a lot harder, hence losing much of their energy and size. In saying this we're expected to see a significant amount of storm activity firing up towards WA, with medium levels of W/SW swell producing contestable waves throughout the first half of the waiting period.

An extra thing to note with these westerly swell events, besides the loss in size across the Surf Coast, is the inconsistency. The storms creating each swell are expected to break down under Western Australia, so the resulting large travel distance, combined with heavy swell refraction into the Surf Coast will create long breaks between sets.

Conditions will be excellent during Tuesday and Wednesday morning with straight offshore winds, but Thursday is looking less than ideal as light E/SE winds develop. We may see winds swing back to the north through Friday as the large swell peaks but we'll provide another update on the Bells forecast early next week.

Short Forecast (updated 2/4/12):

  • Tuesday: 2-3ft waves during the morning, increasing to 3-4ft during the afternoon. Moderate N/NW winds, tending SW during the afternoon.
  • Wednesday: 4-5ft waves during the morning, easing slightly into the afternoon. Light N/NW winds, tending variable during the afternoon.
  • Thursday: 3-4ft waves early, building to 4-5ft during the afternoon. Light N/NW winds, tending SE during the afternoon.
  • Friday: 4-6ft waves early, easing during the day. Light N'ly winds, tending variable during the afternoon.
  • Saturday: 3-4ft waves early, easing during the day. Early W/NW winds, tending fresh SW during the day.

//CRAIG BROKENSHA

Comments

winkipoporbells's picture
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winkipoporbells Thursday, 29 Mar 2012 at 7:11pm

Hmm this is a great surf report comp between swellnet and coastalwatch who will be correct swellnet forecasting much smaller waves with coastalwatch pushing multiple days in the 4-6 6-8ft days.
I will watch with great interest. YEWWW

z-man's picture
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z-man Thursday, 29 Mar 2012 at 7:30pm

the amount of online viewers is directly proportional to the swell size.
A smart advertising/forecaster could profit(his company rather) from the knowledge of this equation.

It should look something like: S+Wx20,000=$
$ - dollar amount
S -swell
W -weather
20,000 - randomly chosen amount of would be viewers.(there are no symbols available on my computer to add the small 2 right after 20,000 to designate squaring that number under optimal conditions.

You can reduce the total $ amount if Bells isn't epic or nearly so, because I won't be watching.

How many Bells T shirts does any one person want to own?

southey's picture
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southey Thursday, 29 Mar 2012 at 10:52pm

HMMM , FRIDAY ....... I know thats a GOOODDDD Forecast .....! Just depends on your Focus ayyy ....

ando's picture
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ando Friday, 30 Mar 2012 at 7:53am

I agree with winkypoporbells...these guys have gone out on a limb and Craig's even claimed forecasting for Vic way more reliable than most of Aust's east coast....so we have a good blueprint to cross check...my lastest charts analysis indicates a possible devil wind early....and no matter whats happening under Sth Aust and West Aust...the devil wind can kill it off....the wind makes and can kill the swell........I seriously hope Craig and CW's forecasts are right and my morning check today is wrong...but I've seen too many 7 day out forecasts go horribly wrong...lets see todays report and cross check it with the last one...

top-to-bottom-bells's picture
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top-to-bottom-bells Friday, 30 Mar 2012 at 8:16am

I'll put money on the event website overcalling it by a foot or two each day. For similar reasons to Z-man above. If your going to do a crosscheck do it with YOUR OWN EYES and not what the ASP say.

thermalben's picture
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thermalben Friday, 30 Mar 2012 at 8:29am

Five consecutive days of surf in the 4-6ft range - with one day reaching 6-8ft - is at a rough guess, probably a one-in-five year event. It's a very significant call by anyone's standards.

Here's the most crucial point regarding this forecast period - swell direction.

Sure, this series of weather systems is very, very impressive but it's all riding very high up in the Bight. As such the resulting swells will have a lot of west in their direction. This shaves off a considerable amount of size along the Surf Coast.

It's also worthwhile comparing the storm track of last week's swell to the upcoming activity. Last week's swell was generated by a powerful storm located inside Bells' perfect swell window - just a shade south of SW.

These impending weather systems will be aligned much less favourably in direction for the Surf Coast and they'll also be located a greater distance from the Victorian coast (compared to last week's event). Therefore resulting in less size at Bells due to refractive effects and swell decay.

I have no doubt that we'll see many days of great waves at Bells next week but I think Craig's size outlook is much more realistic given the current chart projections.

whaaaat's picture
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whaaaat Friday, 30 Mar 2012 at 8:59am

Hmmmm, lot's of westerly directed swell, eh? Move it to the Mid Coast in SA is my advice. Seaford is a very challenging wave. And there's lots more parking for tourist buses etc.

freeride76's picture
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freeride76 Friday, 30 Mar 2012 at 9:03am

Smucko could do water patrol/security.

whaaaat's picture
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whaaaat Friday, 30 Mar 2012 at 9:05am

Yeah, and take everyone to that secret spot of his on the Fleurieu.

Wait a minute, mebbe it is Seaford?

thermalben's picture
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thermalben Friday, 30 Mar 2012 at 9:14pm

Holy guacamole. It's a postcard-perfect forecast of sustained solid swells and perfect winds for South Oz, one of the best I've seen in a long time. Epic from Tues thru' Fri next week. Oh to be on the road!

Winds could be a little funky for Torquay though, later in the week. Tues/Wed should be OK but Thurs/Fri look tricky.

southey's picture
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southey Friday, 30 Mar 2012 at 10:39pm

4-6 ft WSW is perfect for Outside Rincon to connect thru to the Bowl .
BUT we all know that SA is where the wave are , ay Steve ......

PS . Anyone interested in a 20 SEC interval Swell arriving at the end of this ( Friday/Sat ) ?????
And what appears to be the weirdest Forecast of , Nothing Behind it in the way of Strong winds .....

Either the work experience kid's been left on his own in Model land , or SEAFORD is the Future of the Aust . leg of WTC ..... heheheh

thermalben's picture
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thermalben Saturday, 31 Mar 2012 at 6:29am

Craig mentioned the Friday swell in the article above, southey - it does look very impressive on paper, but again, this swell will be very westerly in direction - and it will have been generated even further away from the mainland (between Heard Island and West Oz) which will have a significant impact on wave heights at Bells.

the-roller's picture
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the-roller Saturday, 31 Mar 2012 at 11:19am

definitely looking forward to an epic Bells test match....

Now, does anyone happen to know the line that odds makers have set for a third consecutive ASP event sans any Aussies in the semis and or finals?

Doo dah, doo dah.....

donweather's picture
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donweather Saturday, 31 Mar 2012 at 12:20pm

"Here's the most crucial point regarding this forecast period - swell direction.

Sure, this series of weather systems is very, very impressive but it's all riding very high up in the Bight. As such the resulting swells will have a lot of west in their direction. This shaves off a considerable amount of size along the Surf Coast.

It's also worthwhile comparing the storm track of last week's swell to the upcoming activity. Last week's swell was generated by a powerful storm located inside Bells' perfect swell window - just a shade south of SW.

These impending weather systems will be aligned much less favourably in direction for the Surf Coast and they'll also be located a greater distance from the Victorian coast (compared to last week's event). Therefore resulting in less size at Bells due to refractive effects and swell decay."

Gee I wish I had said something similar to the above a week or so ago in Craig's LWT discussion.

Craig's picture
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Craig Saturday, 31 Mar 2012 at 1:59pm

I had a post prepared of a similar ilk in the LWT article as well but didn't add it in as I was preparing this article. While the LWT came around again as expected it's a shame it is being focussed up towards WA.

Still I'm sure the Western and Southern Australian's aren't complaining ;)

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southey Saturday, 31 Mar 2012 at 3:56pm

The SWA's will be complaining , the bulk of the swell will drift pass whilst they have 5-6 days straight of the " devil Wind " Straight west ! Not even one half day where the wind may swing back more southerly .

I understand you guys with the swell direction . BUT i also know that 95% of Victorians don't understand Swell direction especially those that never venture " out of Bass Straight " .... In the times that i've bothered to travel to surf Solid Bells / Winki , locals would call it too Sth and too West ( of the direction of swell actually hitting the Reefs .

As has been mentioned elsewhere on this site , people often get it wrong when confronted with what they see on the waters edge if they haven't studied where exactly its coming from . Any swell with Two S's in it that inpacts the shores in the Torquay region actually has to Negotiate King Island . So i laugh when Locals talk about a Sth Swell in that region .......
I would of said that a Sth would have to refract and actually peak on the reefs in what appeared to be a more Westerly Peak or line coming down the Reefs , and Vica Versa for W swell . I'm probably wrong but i reckon I'm on to it when the Swell is a long interval ( solid swell ) . The shallow Bathymetry of Bass Straight will change this effect as the swell gets bigger .
A perfect example of this is if a Dead Straight SW 15 ft ocean swell is running at places well west of Cape Otway (and to be extremely accurate closer to the SA border [ very narrow continental shelf ]. So waves would be close to that 15 ft in exposed SW facing spots , but at the same facing spots well inside Bas Strait " Gunna " it will only be 8 ft and "stacked" ie no real change in heights from sets to lulls . Just " Cordoroy " .....

As for Swell decay , unless you talking of the shallow Bass Strait , providing this then i would disagree . As notoriously Bass Strait only really does this when the Wind is howling offshore/cross Off . If the wind is slight it tends not to dampen these incoming " visible swells " ( visible due to them feeling the Bottom ) . The other notable thing is ( especially before computers ) that often the cleaner bigger swells never actually showed up on the old Newspaper/TV synoptics , Back in the Day !!!!!

A question of everyone if i May .......

How many people that are involved in this topic , have actually Targeted Solid swells for themselves to travel a fair distance for to just ride waves in the Torquay Region .( ie not already there or heading there , day trip / weekender just to surf a swell !!!?

And "Surf Coast" is a bit General , when discussing purely swell , as Apollo Bay end will be different from Queenscliff ......

Cheers Guys.

( Oh Steve , Contact me if you wanna chase some decent waves whilst your here for the Comp. )

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Craig Saturday, 31 Mar 2012 at 4:30pm

Hi Southey,

Firstly regarding swell direction, King Island has little effect on strong S/SW groundswells pushing into the Torquay and Bellarine Peninsula area from my experience and perform exceedingly well in these areas (compared to a SW swell of similar size).

The swells are usually generated by strong polar fronts to the south-west of Tassie but even a fetch directly off Tassie's West Coast isn't impeded as shown in this article.. http://www.swellnet.com.au/news/2213-two-degrees-of-separation

Secondly with swell decay, we are talking abut swell refraction, with a swell coming in from the west having to bend 125 degrees around to the left (back on itself) hence losing a considerable amount of energy. When the swell is south-west it only had to refract around 90 degrees and this can be seen easily with the size difference between the Mornington Peninsula (MP) and Surf Coast on varying swell directions.

I.e. on a SSW swell the Surf Coast could be 3-4ft, the MP could be 4-5ft.
On a SW swell the Surf Coast coule be 3-4ft and the MP 6ft+
Then on a W/SW swell the Surf Coast could be 3-4ft and the MP will be 6-8ft.

So this differences in size is what we are referring to when saying the swell energy will be lessened due to extra refraction from its true direction.

Re people targeting large swells to surf themselves around Torquay, I haven't done this myself but have advised many on large swell events in that region (a recent example, Stu made the flight down to Torquay for last Friday/Saturday's swell on news of a large swell nearly a week in advance).

Oh yeah, and WA will cop the wind, didn't look at this too closely so SA looks to benefit the most!

z-man's picture
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z-man Saturday, 31 Mar 2012 at 9:15pm

I think we have a consensus. Bell's will be a GO!

Maybe not 'all time' but contestable.
I have next to no experience whatsoever re Australian surf predictions, but if I recall the 2nd site location - Winki Pop? - is a great 'down-the-line' wave that could come in to play because of the predicted swell angle?

I'm OK with that - I'm sure it's a job to move all the event stuff - but the wave there, If I recall, is well worth it!

We don't have to wait too long - either way, here's hoping for good to great surf and winds!

southey's picture
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southey Saturday, 31 Mar 2012 at 11:25pm

I think its all been summed up by Craig's post ...........

I wasn't talking of the obvious swell refraction , as a Teenager that stuff was a given .

If Stu , has 5 mins to spare , can he tell me how epic it was last week ???? hehehehe

And as for others that had a taste for " Burrito's " , I reckon they would have been left a little empty and Ordering More sand , if it was a menu Option . Even the Locals didn't surf there specifically!!!

Forget MP ( the coast ) , look west to see the Swell differences at differing angles .

In Summary , a really big swell works best on on SSW swell at Torquay region , but saying that- there is a far more obvious difference in open Ocean to Torquay region size wise than when its WSW .
And the main crux of what i was saying was that a large SSW swell actually runs down the Reef better ,( at say Winki than , a straight SW ) {{ how many of last weeks set waves were made at Winki ??? It isn't due to swell size !!! }} . I'm saying that all large swells apart from straight SW refract into Bass Strait . Look at the 200M depth line west of the Strait , If its south it starts refracting ( slower on the South edge ) and (west slower on the Nth edge ) . So as these swells hit the angled coast , one will build as it runs down a RH point , the other will decline . And Bells and Winki need opposites ( Building = bells ( the Bowl/horse shoe ) ,
[ declining = so it doesn't race off down the line ] ...... hence bells , especially Outside Rincon would want the WSW over SSW . ???? !
" Bangs head against wall "

If you guys don't get me , then say so . Otherwise its a waste of time !

Cheers

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southey Saturday, 31 Mar 2012 at 11:47pm

PS .

www.swellnet.com.au/news/2213-two-degrees-of-separation

This demonstates the swell direction " opposite to what would be thought on paper " ....

BUT , I KNOW that the Burrito's were HOT on that particular day .... Almost Burnt my Fingers ... Heeehe

thermalben's picture
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thermalben Sunday, 1 Apr 2012 at 5:53am

southey, you're confusing me a little on this topic. Seems there are two discussions going on - (1) swell size at Bells relative to storm position, strength and orientation, and (2) wave quality at Bells relative to swell direction.

The second topic ("wave quality at Bells relative to swell direction") is a moot point - I can assure you the contest directors won't be picky about swell direction at Bells. If it's at least 3ft and clean, they'll press the green light. If it's inconsistent they'll move to Winkipop. They won't sit around and say "nah, it seems to have too much west in its direction today, let's call it off and wait for another swell with a better direction".

As for the first topic ("swell size at Bells relative to storm position, strength and orientation"), then it's a much more complex issue - I've seen epic surf from just about every quadrant of the swell window. However there are a few reasonably hard and fast rules, so it'll be interesting to see whether they stand up to the test over the coming week.

thermalben's picture
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thermalben Sunday, 1 Apr 2012 at 5:58am

Also, it's interesting to see that Coastalwatch have downgraded their forecast in recent days.

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thermalben Sunday, 1 Apr 2012 at 6:39am

southey, you said "As for Swell decay , unless you talking of the shallow Bass Strait , providing this then i would disagree."

When I mentioned swell decay, I was referring to the loss of size due to large travel distances. If we have two identical fetches generating identical swells in the Southern Ocean, but one is located a thousand miles further away from the Victorian coast than the other, then the corresponding surf size in Victoria will be smaller due to the loss of size over the extra travel distance.

And that's the main point regarding Friday's swell. It's been generated further away from the coast than the mid-week swells, so despite being very impressive in size at its inception, we have to knock off some size at Bells due to swell decay.

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Craig Sunday, 1 Apr 2012 at 6:47am

In no way did I tell Stu it was going to be epic Southey.

I told him exactly what to expect, and guess what he had an absolute ball out there on Friday and Saturday with one session seeing only him and one other out at Bells on Friday afternoon. How's that, the most discussed swell of the year and besides one other, a guy from Sydney that flew down for the swell was out surfing 8ft Bells.

I don't quite get what you're getting at any more but Ben and myself have tried to explain most of your points and if you read over them again it should cover all of your questions.

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southey Sunday, 1 Apr 2012 at 11:10am

Thanks for your time Guys .....

@ Craig , I'm all for people getting solid uncrowded waves . But maybe Stu would of been even happier a little Further West ( admittably with a reasonable Crowd ) .

As for swell decay , i know you guys are classically trained ( so I will take your word for it ) . But i can't understand that if a swell that hits Mexico and has travelled from the Sth (half way across the Globe to get there ) and is still extremely solid . I also understand that it will travel better through the " duldrums "? .

Then i would of thought that our typical swells would only decay from a significant other wind /front that effected it in its path from wherever west of here . Now if the wind stays from a similar Quadrant for 5-6 days Straight and the swell meets ever decreasing wind speeds as it gets closer to shore then that wouldn't be as much of an issue ? Obviously consistency would be an issue for these swells especially at an open ocean size of only 10-15 ft and possibly approaching 18-20 sec's intervals . But surely with lesser westerlies to persist along the swells path as it approaches , then we won't see that organisation and swell intervals may only approach 14-16 sec's . or is this primarily a case that they will have intermixed swell trains coinciding . ?

If the East swell anticipated for SNSW dies out , will you guys see a Greater circle path effect . ? I know i've surfed a long range swell in far western Vic , and then 3-4 days later Surfed the same 16-18 sec interval swell with stunning success..... ?

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thermalben Sunday, 1 Apr 2012 at 11:59am

Wave decay only relates to swell size. Not its period. However, because the 'strength' of a swell is also proportional to its period, and because of Mexico's exposure to long period swells from the southern hemisphere (and due to a few other reasons, such as local bathymetry), the waves there are usually 'solid'.

In contrast, the same swells that reach Mexico also pass through other locations closer to its source (ie Tahiti, Easter Island), and consequently wave heights at these nearer locations are often of the same strength, but much greater in size. This is because - being located closer to the source of the swell - there is less size decay to the shorter travel distance.

"i would of thought that our typical swells would only decay from a significant other wind /front that effected it in its path from wherever west of here"

The studies I have read suggest that swells do not lose much, if any size or energy under opposing wind regimes (I'll have to chase up the paper I read this in though). My personal opinion is that short period swells are often affected by strong opposing winds (for example, a NE windswell in Sydney, against a gale force SW wind), which can erode their size and strength relatively quickly, depending on the circumstances. This is because short period swells have a larger percentage of their energy near the ocean surface, compared to long period swells - so they're more susceptible. However there may be other reasons for the apparent loss off size under these circumstances.

Regarding your last paragraph ("will you guys see a Greater circle path effect"), I'm not quite sure what you mean. Are you saying you surfed a 16-18 second groundswell in Far West Vicco, and then surfed the same swell 3-4 days later somewhere else in Vicco? That doesn't make sense to me - the time elapsed between surf sessions is too long for it to have been the same swell (although it could have been a secondary pulse from another fetch related to the parent system).

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southey Sunday, 1 Apr 2012 at 12:57pm

Yeah got you on the swell decay , just don't understand if its 15-20 ft in Mexico , how big is it in Tahiti surely not more than 1.5 x that size ??????
So a loss of less than 50 % over 3-4 times the distance we are talking about here under Australia is not really conducive to large portions of Size loss ?

The Famous Corduroy Effect in shallow Bas Strait waters is pretty obvious , a deep ocean swell feels the Bottom and nearly all the Swells energy sits on the Surface , as the Waves feel the bottom for Hundreds of KM's . You only have to see how Quickly a Long range swell gets beaten down by a Strong offshore in these Parts >... ? maybe we can get some Funding !!!! hehehehh ( I'm sure all the Green energy goons would love to get wave/ swell Generators going )

The Greater circle path reference is about surfing a long distance WSW swell in the past at Vicco's western extreme , and then again in SOUTHERN NSW a few days later ..... Obviously the Tasman will need to have No Easterly swell at all and a large HIGH parked over it . So if this can happen , Bells is far less effected ?

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Craig Sunday, 1 Apr 2012 at 2:04pm

Hi Southey,
Mexico seems to be just one of those places that sucks in and amplifies long period swells extremely well.

I don't have a link here but you can do a quick search and see that half the swell height is lost in the first 200-300nm away from the storm and then it keep on decaying from then onwards.

A quick way to think about it is why do some of those 19-20 second swells that hit Australia that are generated below South Africa have such little size attached. You can't get 19 second swells from weak storms, they are made my monstrous storms and the reason some of those swells have no size is because it was all lost while traveling 5-10,000kms.

Oh and I understand what ya saying with surfing a swell in vicco and then SNSW. But for that to happen the storm has to be at polar latitudes to the south-southwest of Tassie and in SNSW's swell window.

freeride76's picture
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freeride76 Sunday, 1 Apr 2012 at 5:21pm

Mexico's deep-water canyon breaks like puerto and p.......quales...are pretty damm incredible for hoovering up those southern hemi groundies and defying the laws of swell decay.

Agree with Craig about the possible refractive wrap from southern ocean swells into the east coast. They need to be at or E of 130E to have a chance. And Newy and North coast swell magnets pick 'em up better than S.Coast. More room for the swell to wrap/refract.
Different rivermouth/continental shelf canyons seem to all have favourable period signatures which refract best into 'em.
One more piece of the puzzle.

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southey Sunday, 1 Apr 2012 at 11:48pm

hence my point that unlike what some published literature has provided , alot of a swells energy is held well under the surface when travelling through deep oceans . although Bass Strait is shallow , it's narrow and has an opposing Tide flow to typical swell flow . So a swell will concentrate weirdly through this ( channel ).
i have much respect for Ben and Craig , but i also know that most research is conducted in lakes and the scales aren't the same .

But this is all talk . 10-12ft waves were ridden today . and i was otherwise disposed .

thermalben's picture
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thermalben Monday, 2 Apr 2012 at 6:48am

southey, I think you're confusing yourself. What literature have you read that claims that most of the swell energy is NOT held well under the surface?

You are correct - "Bass Strait is shallow, it's narrow and has an opposing Tide flow to typical swell flow" - yes, all of these factors (and others) have a direct influence on wave heights between Apollo Bay and the Prom.

However.. "most research is conducted in lakes" - that ain't true. A significant amount of research I reference has been done in the open ocean environment.

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brutus Monday, 2 Apr 2012 at 8:15am

interesting discussion in theory,but a few facts/statements need to be tuned in...

If you watch the buouys,and the swell directions everyday for a few years there are some startling observations.

Swell direction....we get swells from 258`- 168`...and every direction in between breaks differently,even if its slightly different where the swells hit the reefs.

WSW,240`+ is a great direction swell for bells,as it peels further from behind rincon and breaks all the way thru,Winki is much smaller and is not at its best on these swells.....

as the swell swings more into the SW there are the occasional inside peelers at Bells,but it hits mostly in the bowl,and this is when winki lights up.......

as the swell goes more south,it gets way more consistent ,and bigger,and true south swells of 195` or less,make winki and Bells go ballistic....supa consistent ,20 wave sets and peeeeeel for .....

I think that the RC Pro,will have some very good waves,probably what we call 3-4' with sets,a bit inconsistent,but a good direction for Bells and with the swell predicted to be above 14 secs,should be some corduroy lines.......swell direction doesn't look good for winki,as it will be at least a 1' smaller than Bells.

should be a great comp,as its gunna be supa shredable...except for friday which looks like a bit too north,and will blow into the tube..

As for the other weekend,crap flat burgers,SW swell but more of a wind swell.....waves were much better Mon,tues,weds,thurs...and no-one out!!

thermalben's picture
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thermalben Monday, 2 Apr 2012 at 8:54am

Great stuff Brutus - appreciate your insight.

Just out of interest, when you refer to specific swell direction degrees ("WSW,240`+ is a great direction swell for bells"), can I assume you're referencing the numbers given by websites like Buoyweather?

I also assume you're referencing an offshore location, perhaps somewhere like NW of King Island.

The only physical wavebuoy with directional capabilities is offshore from Point Nepean, however the direction of the swell is already attenuated by the time it reaches this point so it's not always indicative of the regional swell direction.

anton-chigurh's picture
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anton-chigurh Monday, 2 Apr 2012 at 9:25am

Guess what , a secret buoy exists. and shows all.

thermalben's picture
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thermalben Monday, 2 Apr 2012 at 9:27am

Anton, I know of the secret buoy (thylacine?). It's not directional though.

thermalben's picture
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thermalben Monday, 2 Apr 2012 at 9:27am

Actually, it's not a buoy either.

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brutus Monday, 2 Apr 2012 at 9:50am

the point nepean buouy is what we use for this coast,and when you learn to factor in outgoing/ incoming tides,depending on to tide co-efficient...which can make the swell directions change up to 15` in a couple of hours....

alot of people think that incoming tide brings up the swell here,what i have noticed is incoming tide actually makes the swell come in a bit more south,which is a bit bigger and more consistent....

freeride76's picture
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freeride76 Monday, 2 Apr 2012 at 9:53am

How could the tidal phase effect the swell angle?

Via refractive effects from the shallow Bass strait bathymetry?

Genuinely curious.

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rswin Monday, 2 Apr 2012 at 9:59am

This is a very interesting discussion. Props to all contributors.

What I don't get is why some people (Southy I'm looking at you) feel the need to make continual references and allusions to otherwise low profile spots. Yes man, we know you know, please don't keep broadcasting your inside knowledge for all the world to see.

And please take these comments in the humble spirit in which they are intended. Your general comments and insights on forecasting demonstrate a wealth of experience.

Use your powers for good man, not evil!

Peace

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thermalben Monday, 2 Apr 2012 at 10:11am

Brutus, I'm personally a little suss on the direction readings from the Point Nepean buoy. I've spoken to the guys who have installed a number of wave/current/tide sensors in that neck of the woods, and they tell me that the entrance to PPB undergoes radical changes on the turn of the tide, and under different swell conditions.

As such, I don't know if there's a sure-fire way to look at the Nepean buoy data and deduce the precise swell direction (which is exactly what a calibrated buoy is meant to do).

It seems to be pretty good with height and period though.

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southey Monday, 2 Apr 2012 at 10:22am

Brutus is onto it . As Thermal says though , those swell directions can change up to 5-6 times in a particular tidal flow .

@ rswin , my humble apologies . and i shall drag my unworthy body back to under which rock it did cometh .

i like to talk swell directions in this neck of the woods , as it is
A ; not what people think even if they are local and have seen it all
B ; everything in this neck of the woods isn't as it seems
( adding to mystique ) , i at no point in time told whoever to go where .
And if anything my words have only confused those that should know ....

Withdrawing to not be seen again ......

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thermalben Monday, 2 Apr 2012 at 10:24am

hey southey, don't withdraw from the convo - I'm enjoying the banter.

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Craig Monday, 2 Apr 2012 at 10:28am

Yeah, don't go Southey, I love the way you think and analyses the weather and swells so much. Keeps me thinking!

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southey Monday, 2 Apr 2012 at 10:37am

i didn't actually surf yesterday , spend more time pondering it that doing it of late .
but just like old stories . If you see me travelling towards a coast , you know it will have to have been good enough to drag me out .....

Ben , i haven't seen these latest " research's " , i do know the most comprehensive studies that' I've read involved Lakes in and around Canberra . ( ask Greg W ) .

If Argo can't get the water temps right over an extended period , what chance do we have of measuring deep water swell ? You need to talk to the Oil Rigs west of Cape Otway for insights . Many involved there would have a long history involved in Bass Strait , going back to its roots in Eastern Bass Waters for the last 30+ years ....

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rswin Monday, 2 Apr 2012 at 11:36am

Now this is probably a very elementary question to be asking blokes of your calible (southey, craig, ben et al).

What affect does wavelength (period) have on the rate of refraction / diffraction? That is: is a long period W swell more or less likely to bend around Cape Otway than a short period swell of the same direction?

Been a long time since high school physics class ay!

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brutus Monday, 2 Apr 2012 at 12:09pm

to me all the nepean buoy is an indicator,and as i have watched it daily for a few years now.....I never thought that tides had any influence on swell direction in Bass straight,until i witnessed first hand changing ,conditions based on swell direction...

i now have documented 13 different swell directions,that all seem to make each spot better or worse....depending on swell strength,or what the second period is.

WSW swells are best 15 seconds & above,so they can bend round the corner of Otway,whereas a South swell can be 10-11 seconds and still perfect.....

and with the swell size etc...the cape sorell buoy is what I use as the best indicator of whats happening with the ocean swell......

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rswin Monday, 2 Apr 2012 at 12:25pm

Take your point that the Cape Sorell buoy is only an indicator Brutus. However, CS is actually further east than Queenscliff. Am I correct in reasoning that wsw swells will hit the vic west coast before registering on the CS buoy?

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Craig Monday, 2 Apr 2012 at 12:50pm

Hi Rswin,

No question is too simple, but yes longer period swells refract and bend in more as they have more energy below the surface than shorter period swells, and feel the ocean floor, hence bend in along the contours.

And regarding Cape Sorell, all swells from the West to South will hit Cape Sorell first before impacting the Barwon Heads because it is in open water, with the swells slowing down as they head through Bass Strait.

So even though geographically you are right, there shallow water through Bass Strait slows the swells and they tend to arrive 3-4 hours after hitting Sorell.

Also the thing to consider is that most swells are from the SW hence Cape Sorell is actually closer than Queenscliff to the oncoming swell (tilt your map on a 45 degree angle and you'll see this).

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anton-chigurh Monday, 2 Apr 2012 at 1:38pm

it exists. directional etc. good luck finding it tho'

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thermalben Monday, 2 Apr 2012 at 1:42pm

Any hints Anton? Is it in Vicco, Tas or SA? And is it a buoy, or another kind of device? There are a number of privately owned buoys around the country; some allow access, some don't.

I know of three wave measuring units in Vicco besides Pt Nepean but only one of them is relevant to the Surf Coast.

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thermalben Monday, 2 Apr 2012 at 1:45pm

Actually, make that four additional wave measuring units in Vicco (besides Pt Nepean buoy). Just remembered another one.

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rswin Monday, 2 Apr 2012 at 3:19pm

hey anton, shhhhhh

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thermalben Wednesday, 4 Apr 2012 at 7:22am

Interesting difference of surf-size opinion from Bells Beach this morning.

Damien Hardman was interviewed on the webcast by Toby Martin just after 7am, and he said that the swell was 'around the same size, perhaps a little smaller and less consistent than yesterday' (or words to that effect).

On the other hand, the official ASP Press Release just landed in my inbox, which quotes head judge Richie Porta as saying "Conditions are significantly bigger and cleaner this morning".

Regarding the surf, the press release also says "Pumping three-to-five foot (1 – 1.5 metre) waves are steaming through Rincon and the Bells Bowl this morning". Yesterday's post-competition press release stated Tuesday's waves were 3-4ft.

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amb Wednesday, 4 Apr 2012 at 8:27am

Cranking swell (by Mid Coast standards) last night well done on picking it 7 days out Thermal

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thermalben Wednesday, 4 Apr 2012 at 8:32am

Wasn't me AMB - Craig did all of the hard work! Stoked you scored some waves. Wouldn't have minded being over at Yorkes though..

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southey Thursday, 5 Apr 2012 at 12:18am

How's what some of the " models " are playing with in regards to the second half of the weekend .
But then GFS , goes all loopy and has a Cut Off form in the bight and then Retrograde NW ??? !
( Probably ignore this now ) .

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thermalben Thursday, 5 Apr 2012 at 6:42am

Yeah, it'll maintain solid swell through the first few days of next week.

EC doesn't have the short wave feature and keeps the upper trough further south in latitude, however the broadscale synoptic pattern is generally similar - so there should be a medium/high level of confidence for this pattern to play out.

Looks like local winds will tend fresh and gusty southerly on Monday, but I reckon there's a reasonable chance for a brief W/NW wind in Torquay at dawn.

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thermalben Thursday, 5 Apr 2012 at 6:59am

Jeez, the latest wave obs from the Cape du Couedic buoy are off the hook. Some of the most amazing figures I have ever seen for a clean groundswell. Wouldn't be surprised if this morning produces some of the biggest waves seen in SA waters at some of the offshore bommies.

http://www.bom.gov.au/products/IDS65030.shtml

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Craig Thursday, 5 Apr 2012 at 10:37am

Wow, those readings are phenomenal.

To have light winds and a 6.5m @ 18seconds is incredible.

Couldn't even imagine what parts of the South Australian and Victorian West Coast would look like!!

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victor Thursday, 5 Apr 2012 at 11:48am

cape de couedic would be looking a lot like a world class tow wave with that size and conditions.

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southey Thursday, 5 Apr 2012 at 9:44pm

Just got home from an Epic day .......

I was wrong about Friday , Thursday was it .......

Oh and Steve deserves a raise , for towing the " company " Line ........

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thermalben Friday, 6 Apr 2012 at 8:19am

How big southey?

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southey Friday, 6 Apr 2012 at 9:13am

I've seen it bigger . But I've never been in the water , where its been so clean ALL Day at that size .
With the new swell mixing in , I'd say that around 4 pm it was the best I've seen it .
Probably undergunned & ( under prepared - fitness wise ) , so we'll use that as " the measurement " .
From what i heard , T & K probably picked the wrong day . And today who cares .