Tweed waverider buoy today

[DaneCross]

Just had a look at the Tweed WRB and it seems to indicate a 10.5m wave at about 10am this morning. Is that bullshit or what? That one(?) wave is at least 3x the size of the Hsig at the time. 10.5m is a serious wave, imagine coming across that fella on the Tweed bar :o What causes these 'rouge' waves?

[Willo]

Yeah DC
Had a look at Burleigh Heads at about 8.00am this mornin and it was hugeeeeee Storm conditions there.and down Tweed way always picks up more swell, wouldn't surprise me if a couple of big storm sets come marchin through.Would have liked to have seen them hitting the Bar :o

[Mick]

Nup, not possible. Not over just an hour or 2 anyhow, unless a meteor has struck the ocean off shore or an underwater volcano / earth quake has erupted.

For a 10 meter plus wave to come rolling through, we are talking about a catergory 4 or 5 cyclone that is stationary and has been spinning for days just off the coast.

Also I believe the wave rider buoy only measures the swell height and not the wave height (the buoy is not located in the surf impact zone). A 10 meter plus swell is not a 10 meter wave. It would more likely have a face of about 14 or 15 meters. There would be some serious damage if that happened.

Interesting graph DC, good spot!

Mick

[Willo]

We get pretty big waves down there, wasn't all that long ago they were tow in surfing 15-20ft waves off point danger

[razorline]

i have regularly seen the point lookout wrb read sea height up to 13m over the years - quite a few times over 10m. i believe it is very possible the tweed reading was genuine.


simon

[Cloud_9]

Dc your spot on.
The weather buro just had that 10.5 m swell on the news
50knt winds sand bagging going on at tallabugera.
weekend fishing looking stuffed :-/

Cheers cloud 9

[gunna]

Thats a good example of having 3 times depth of anchor rope out. Not that you would be out in those conditions - but a wave like that would sure bury the front of the boat if the rope was a bit short.

[DICER]

Entirely possible, given that it took 36+ hours as the waves increased in height. Have a look at these articles:

http://www.newscientistspace.com/article/mg17022974.900

http://www.newscientistspace.com/article/mg17022974.900

[DaneCross]

Ok here's todays update... 17m hmax :o :o With 5m hsig. Now thats BIG :o Makes yesterday look like a lake ;) ;D
DC

[Cloud_9]

update on the wave rider at the tweed.

7:30 am today 17m monster recorded.

[rando]

17 mts,, :o :o thats southern ocean conditions!!!.
I read a report some years ago about the winner of the first round the world yacht race, a maxi-yacht named Rothmans they experienced 70 knot winds and were regularly sailing with full hoist main & spinnaker in 40 knots, ( thats a lot of sail for the uninitiated) doing cutbacks & re-entries on 50ft waves ( this is an 80+ ft yacht remember), helmsmen changed watch every 1/2 hour because that was as long as they could handle the fear factor

[Fishinmishin]

I WAS OUT! IT'S REAL! :o :o :o :o
Lucky I got away OK ::) ;D.

[Mick]

There must be an explanation for these graphs because I will chew my own leg off if a 17 meter swell hit the tweed coast. I don't even believe a 10 meter swell.

A 10 meter swell would already be breaking records for the biggest swell to hit QLD, let alone 17 meters.

Can someone explain what is going on, cos I don't believe a word of it. All other reports are saying 3- 5 meter swell, which is already bloody huge. 17 meters is just captain goodvibe stuff out of cartoons.

Mick

[blaze]

we get 20m a couple of times a year on the cape sorrell wave rider on the west coast of tassie, the ab divers dive up to 4m swells. mad i reckon
cheers
blaze

[Mick]

I beleive that Blaze. The south and western parts of tassie regulary gets crazy waves that big (I have seen footage of shipsterns bluff at about 7 meters which was nearly unridable for surfers). The margret River coastline, Northern California, Hawaii, The South American Cape and the South African Cape are all places open to raw ocean energy but the Tweed Coast is not. It would take a serious cyclone or something similar to produce waves that big on the eastern coast of Australia.

[gogecko]

I believe it. Ive seen 30ft waves at Burliegh Heads during the 1990 cyclone. Rabbit and a few pros were riding them, too.

Yesterday we had a low form off the coast, but it wasnt warm enough to be a cyclone. Similar conditions tho.

I expect this anomoly in wave size is explained by the fact that BOM issues swell forecasts in average swell, so 3-5m swell could have some 6-8m swells as rogues.

Surfers know that the wave face is twice as high as the swell becasue off the sucking effect foreward of teh wave. An 8m swell could easily produce a 17m wave face. A bouy would measure wave face and not swell.

We had a BOM member lecture at VMR recently, an he advises that wind is also measured in averages. 15 knots forecast means up to 30 knot gusts.

[dasher]

There must be an explanation for these graphs because I will chew my own leg off if a 17 meter swell hit the tweed coast. I don't even believe a 10 meter swell.

A 10 meter swell would already be breaking records for the biggest swell to hit QLD, let alone 17 meters.

Can someone explain what is going on, cos I don't believe a word of it. All other reports are saying 3- 5 meter swell, which is already bloody huge. 17 meters is just captain goodvibe stuff out of cartoons.

Mick

Uhm would you like fries and a coke with leg sir. ??? ;D ;D

[NQCairns]

A bouy would measure wave face and not swell.
Thats good info #[smiley=2thumbsup.gif] that I had never twigged to before, I assumed it was a vertical measurement trough to tip- any way the verify?

Even 10m sounds like a news media report style of measurement, if 17 is correct I am giving up boating :o, in anyhing less than 25m deep or so that is a breaking wave [smiley=end.gif] nq.

[Mick]

I am almost certain the bouy does not messure the wave face. The most accurate means of measuring a wave face is by photograph. This was discussed at the last Billabong awards night (cant remember the name, The odessey is familiar).

I have surfed all my life all over Australia and I have never seen a 30 foot wave. Sorry, I just cant fathom or swallow the notion of a 17 meter swell. I am guessing the readings are a combination of seas and swells. I figure there could be troughs to 6 -8 meters and swell to 6-8 meteres, so if there is a trough right next to a wave the bouy would read the two measurements put together. This is the only thing making sence in my mind and it is still far fetched.

[gogecko]

Hi Mick,
arent we saying the same thing? Trough plus swell equals wave face?

If you think about it, even the name 'waverider bouy' implies this.What sort of design do you think it is? Id guess its a bouy floating on a solid pole. Anything else would sway and give incorrect readings.The bouy would have to ride from the bottom of the trough to the top of the peak, and must be sending some sort of electronic signal to a recorder. It seems it could only be possible to read wave face, and then make averages for swell from such data.

Im only guessing tho, and open to being shown whats going on. Id ring the BOM and ask, except theyd be a tad busy today.

By the way, the 30ft wave face I saw, was reported as 15-20ft swell. I lived on Burliegh beach most of my life, and only ever saw it once. As I said, it was a cat 1 cyclone.Some poor fellas broke thier legropes and ended up 2kms north by the time they hit the beach.Even the jetski supports couldnt get to them. I exaggerate not.There were a couple of hundred specatators there that day.

[rando]

If the waverider bouy is accurate on a swell of 2 to 3 metres why would you then dispute its reading at 17 mts. Its an instrument . its either accurate or its not.
I dont understand the sceptacism?

[gogecko]

A quick check of the epa waverider website shows I was right.

The bouy measures trough to peak, and thus wave face ht. The design is just as Id predicted. The website also offers the disclaimer 'waves can often be twice the height of the swell forecast'.

from
http://www.epa.qld.gov.au/environmental_management/coast_and_oceans/waves_and_storm_tides/wave_monitoring/

"Wave height Once all the zero up-crossing waves in a wave record have been defined, certain features of the individual waves can be determined. One such feature is wave height (in metres), which is the vertical distance between the crest of a wave and the following trough. Wave heights are shown as H1, H2, H3, …, in the sample wave record figure, Figure 2.
Wave length The wave length is the distance (in metres) between one zero up-crossing of the average water level line and the next. Wave length is related to wave period and water depth, such that for a given depth of water waves with a longer wave period have a longer wave length. Or for a given wave period, waves in deeper water have a longer wave length."

Rogue waves are not uncommon at Tweed Bar, although this one was a huge mother.

[Sportfish_5]

Gotta agree with Mick - a 17m swell would be huge - think about the consequences. My understanding is that the waverider buoys measure acceleration up and down the swell. Could it be that it fell in a big pot hole off the back of one of the bigger swell sets ???

http://www.epa.qld.gov.au/environmental_management/coast_and_oceans/waves_and_storm_tides/wave_monitoring/glossary/

Cheers

Greg

[Willo]

Yeah Sportsfish
Your suggestion sounds about right.Gold Coast waverider bouy has registered 8 meter waves as well today.Lot of wild weather is happening here at the moment Coolangatta 369.5 of rain as well today

[blaze]

Dont know how they are attached but I dont think its a pole, believe it to be cable to sea floor as they loose a few down at cape sorrel on the west coast of tassie, some have been found but others never to been seen again.
cheers
blaze

[SeaSaw]

Have you noticed that EPA have removed these rogue waves heights from the latest graph. I think they may have realised that they are not real wave height recordings, but some kind of error events, like suggested by Greg.

Biggest waves are now only 9m ::) ;D Still pretty dam scary :o

Mark

[theoldlegend]

The mystery has been solved !! In this morning's Courier Mail on page 4, the EPA mob said there was a "technical aberration" caused when a wave broke over the top of the bouy.

There you go.

[DICER]

if the wave broke over the bouy then that makes it even higher ;D

was anyone out today, maybe they can verify....

[gogecko]

Yep, the Courier Mail reports that the average waves were 3m, and the rogue wave was only 10.65 m after all.
Wax up the long boards....

[Heath]

Can sure see the affect of all that rain on the old tidal flow...LOL