Continuing strong surf, with tricky winds

Ben Matson picture
Ben Matson (thermalben)

South East Queensland and Northern New South Wales Surf Forecast by Ben Matson (issued Friday 20th February)

Best Days: Most days should have good waves in SE Qld, especially once winds swing to the SW quadrant. Winds will dictate quality south of the border but again, no shortage of swell is expected. Chance for some very large waves, centered around Monday

Recap: What a couple of days, eh? Solid combo of E’ly swells up to 6ft at exposed spots both days with gusty winds anywhere from the south through to the east. Good options at protected points in SE Qld, not much elsewhere (although morning winds have been offshore along the Mid North Coast, with smaller surf).

This weekend (Feb 21 - 22)

’Tis kinda interesting to re-read Wednesday's notes, when the latest model guidance was suggesting that the Coral Sea Low “may reach Cat 1 status just prior to a coastal crossing early Friday morning”. What a difference a couple of days make!day or two makes!

Whilst incredible to observe from a meteorological point of view (and the show ain’t over yet), these developments have certainly thrown a few curveballs our way for the surf forecast. 

Already, wave heights haven’t quite reached the predicted heights late yesterday and today, as was expected on Wednesday. I’ve only got limited time available to hindcast the data, however current thinking is that as TC Marcia began to rapidly intensify - much faster than computer models predicted - this drew energy away from the trough extending south-east, weakening the short range E’ly flow just off the SE Qld coast that was expected to kick up the bulk of the size. 

Initially it was expected that these systems would all merge on Thursday before tracking southwards parallel to the Northern NSW coast on Friday. However as TC Marcia strengthened it also slowed in its forward speed, which has delayed the timing of its merger with the southern trough. STC Marcia crossed the coast this morning near Shoalwater Bay, on the Capricorn Coast of Central Queensland, and is now weakening as is moves overland before it pushing off the SE Qld coast on Saturday afternoon. 

TC Marcia is still then expected to consolidate within the trough offshore from the Qld/NSW border but its future movements from there are still not particularly clear. The latest model guidance is still (!) divergent on where the low will track, however what is clear is that the low will probably remain at least a little more north in latitude than Wednesday’s expectations - if not a lot more north.

And this means that today’s surf forecast is once again very complex, and difficult. 

Right now, current thinking is that we’ll see the existing coastal trough occupy the region between about the Sunshine Coast and Coffs Harbour on Saturday. To the south, winds will be gusty SE whilst to the north - and this includes the Sunshine Coast, and very possibly the Gold Coast - winds will be north-east.

However as the remnants of TC Marcia pushes offshore in the afternoon, we’ll see a broader swing in the wind direction to the SE in all areas. In fact with the Sunshine Coast lying north of the trough’s axis, winds will probably veer NW in the afternoon here, and then SW late in the day. 

So, this brings up a wide range of surf possibilities for Saturday. It’s likely that the morning will be blown out across some northern regions (i.e. Sunshine Coast) early on but a rapid improvement is likely through the day. Wave heights are likely to ease a little from today but should also contain a small degree of short range NE swell (from the developing wind overnight). At this stage we’re looking at 4-5ft+ surf at exposed beaches with smaller surf at protected points. 

On the Gold Coast we should see a similar size on Saturday, and equally tricky winds (variable winds are quite possible at times). In fact surf size should remain a similar size right across the Northern NSW coast but there’s simply not enough confidence in the predicted wind field to pin down a specific time frame where we’ll see the best window of opportunity (unlike the Sunshine Coast where the afternoon is looking the best). Winds may veer more southerly in direction (than the modelled SE) across Northern NSW which would certainly favour the points. But we’ll just have to wait and see what develops.

On Sunday the remnants of TC Marcia will start to restrengthen - probably about east of Ballina - and this will build E/SE swells across the region. Due to the proximity of the fetch to the coast, we’ll probably see a much bigger initial increase south of the border (to 6ft+ at open beaches by the end of the day) however locations north of the border will probably be smaller (say, building from 3-4ft to 4-5ft in the afternoon, with the biggest waves at south facing beaches).

Sunday’s winds will depend on where you are relative to the low. With the axis of the low sitting at about Ballina latitudes, we’ll probably see gusty S’ly winds in this area, tending S/SE south of about Yamba. North of Byron winds should veer more SW and we may even see W/SW winds across the Sunshine Coast. 

So all in all, Sunday looks to be the pick of the forecast period in SE Qld although Saturday will probably have some surprise packages in the afternoon. Winds will create some problems in Northern NSW but as winds strengthen from the southern quadrant the points will really offer the best value.  

Anyway, with such a complex outlook it’ll probably be worth an interim update on this sometime later Saturday - I’ll mention anything relevant in the comments section below.

Next week (Feb 23 onwards)  

Monday looks very interesting. As the reformed TC Marcia winds up east of Byron, winds are modelled to become quite strong around its core - possibly upwards of 40-50kts. Given that this will be positioned point blank inside the immediate swell window of Far Northern NSW and SE Qld, it’s fair to say that we could be looking at some very big waves on Monday

But also - we have to keep in mind the major model revisions that have occurred over the last few days. So, anything is possible. I’ll certainly update in the comments below as we get the latest data and it starts to resolve the future patterns a little more convincingly.

At the moment, it’s likely that Sunday’s increase in E/SE swell will hold strong through Monday as it peaks - possibly upwards of 6-8ft+ at exposed beaches in Far Northern NSW, with smaller waves in SE Qld (and obviously, smaller surf again across the points). Winds are likely to be similar to Sunday, that is - SW north of the low’s axis (around the Byron region) S’ly south to about Yamba and SE south to Seal Rocks. So there should be excellent waves across the region's points once again.

From here on we’ll probably see slowly weakening - although initially still strong - surf from this system, with wave heights likely to tail off rapidly mid-late week.

Elsewhere, persistent trade activity north and north-east of New Zealand this weekend and early next week should ensure a steady supply of E/NE swell in the 3-4ft+ range for the second half of the week right through into next weekend. 

Otherwise, despite the suggestion for a few new sources of swell in the long range, it’s probably better to wait until Monday when we’ll have a lot more clarify on the broader synoptic situation. Have a great weekend! See you Monday.

Comments

Roystein's picture
Roystein's picture
Roystein Friday, 20 Feb 2015 at 9:39pm

I loved seeing the footage of the super bank today as the commercials struggle for footage for their over the top coverage of the cyclone crossing. At no point did I hear them say- " here's some surf at the Gold Coast that is unrelated to the cyclonic weather on the central coast of qld" the tripe they peddle to us at the moment is ridiculous.

Anyway the bonus is the chance of westerlies that aren't dependant on a land breeze with some easterly swell

Roystein's picture
Roystein's picture
Roystein Friday, 20 Feb 2015 at 9:40pm

The other bonus of course is that no one was seriously injured

mk1's picture
mk1's picture
mk1 Saturday, 21 Feb 2015 at 12:07am

Sounds like a lot of fun back home. I'm OS somewhere very flat and kind of boring in comparison. Enjoy the fireworks : )

Ben you said kirra was bigger than greenie and Don said it was the middle bank that springs up when it gets a bit bigger. This does block the rainbow/greenie strip but once past there the swell is also then facing square on to a much shallower kirra sandbar, and I always thought that helped it jack (doesn't happen every swell but pretty common and noticeable when the sets start marching in heading south west into kirra rather than west feathering down greenie).

freeride76's picture
freeride76's picture
freeride76 Saturday, 21 Feb 2015 at 6:53am

maybe we've dodged a bullet here.

donweather's picture
donweather's picture
donweather Saturday, 21 Feb 2015 at 7:09am

You talking about bank buster or flooding Steve? I'm not so sure on the bank buster front with massive amounts if sand being eaten from the dunes and dumped out the back from what I saw yesterday on the big high tides.

freeride76's picture
freeride76's picture
freeride76 Saturday, 21 Feb 2015 at 6:56am

btw, great to see Ben getting down and dirty in the comments with eyewitness reports and updates as the complex situation resolves in real time.
Thats a major advance in my eyes.

thermalben's picture
thermalben's picture
thermalben Saturday, 21 Feb 2015 at 8:29pm

Interesting day of surf across the region - looks like winds held out reasonably close to expectations although the trough made for more widespread variable winds at times.

After being S'ly all night, Maroochydore eventually went gusty E'ly early Saturday morning, swinging E/NE, then N/NE then N/NW before tending light W'ly around noon, before remaining clam through the afternoon and then freshening from the SW late afternoon.

This pattern was somewhat replicated at Moreton Island (with a little more strength, as is often the case) however the Gold Coast remained moderate S'ly all day - which shows where the convergence line was for much of the day under the influence of ex-TC Marcia - slowly drifting south from the Sunshine Coast through to the Gold Coast, also replicated in rainfall totals. 

South of the border, overnight SE gales at Cape Byron (gusting 56kts at 10pm!) swung moderate W'ly at 4am and remained from this quadrant through the middle of the day, before tending SW, S/SW and through the afternoon then settling in from the SE late afternoon where it remains right now. That's a very good stint of favourable winds. 

Evans Head saw a much briefer period of lighter W'ly winds, kick in several hours later than Byron (7:30am) before swinging fresh S/SW mid-late morning and then running through the anti-clockwise trend during the afternoon.

And as we head south of here the 'brief period of favourable winds' was even shorter, with even less westerly component: Yamba swung from overnight E/SE winds to a mid-morning S'ly (at strength) before a mid-afternoon anti-clockwise trend. Coffs Harbour remained moderate to fresh E/SE thru' SE all day.

So on the whole - winds were reasonably close to what was outlined, in what was a very complex day of forecasting. Surf looked bloody good on the Goldy surfcams too (Noosa looked fun, albeit packed - seemed to be a reasonable infeed of NE swell into the Sunny Coast buoys too, as expected - but not reaching the Gold Coast).

And the outlook for the short term?

Looks like the models have again slowed and stalled the reformation of TC Marcia off the SE Qld coast (this afternoon) whilst also weakening core wind strengths and reducing its southwards track.

This means a minor delay and small downgrade in projected size increase for late Sunday through Monday and Tuesday. But the overall trend will still remain the same - great options for the semi-exposed points in Far Northern NSW and SE Qld, with the most size through Mon/Tues (so probably closer to 5-6ft+ at exposed beaches, with smaller surf on the points). 

freeride76's picture
freeride76's picture
freeride76 Monday, 23 Feb 2015 at 9:45am

Good assessment Ben.

Now can you tell me in what parallel universe the Ballina report makes any sense in.

Sat, with straight offshore winds and waves ranging from good to pretty fucking excellent, he gave a 5/10.
Sun, with straight onshore winds and not a single surf spot surfable in Ballina Shire and not a single surfer in the water from dawn to dusk he gave a 5/10. (for comparison the Yamba report correctly identified unrideable storm surf and gave a 1/10)
Mon(today) with similar conditions ie straight onshore 6ft+ surf and not a single surf spot rideable in Ballina Shire he again gave a 5/10. (for comparison the Byron report with the only available surfable options between here and the Coolie points gave a 4/10).

Mate you've got to put some QC on this or this blatantly misleading information is going to land you in hot water.

shoredump's picture
shoredump's picture
shoredump Sunday, 22 Feb 2015 at 1:32pm

good enough for me. I'm going....

udo's picture
udo's picture
udo Sunday, 22 Feb 2015 at 4:11pm

How many more waves can the bank at Snapper take ..will there be any decent sand left for the comp at the end of the week ?

Sheepdog's picture
Sheepdog's picture
Sheepdog Sunday, 22 Feb 2015 at 4:54pm

Can anyone point out to me when and where Marcia became a cat5.....

Middle Percy island (21.66s - 150.27) bottomed out at 3.39am on the 20th - 970.2hpa.... Strongest gust -208kmh...

Samuel Hill bottomed out at 976.8hpa -9.36am.... Strongest gust - 170kmh

Williamson - 987.6hpa -8.30am, max gust - 96kmh

Yepoon - 985.4hpa, 12.30pm, max gust - 156kmh...

Last time I checked, a cat 5 central pressure had to be below 930hpa, with gusts over 279kmh and mean winds of 200kmh.....

Hmmmm........

Sheepdog's picture
Sheepdog's picture
Sheepdog Sunday, 22 Feb 2015 at 5:10pm

Drawn in here overland by BOM as cat 5

Something aint right here......
No need to say "correct me if I'm wrong"..... ;)

thermalben's picture
thermalben's picture
thermalben Sunday, 22 Feb 2015 at 5:35pm

TC Marcia reached Cat 5 status offshore. There are a couple of techniques commonly employed (mainly Dvorak method) which are achieved via satellite imagery.

Sheepdog's picture
Sheepdog's picture
Sheepdog Sunday, 22 Feb 2015 at 6:22pm

Doesn't explain above image and data.... Middle percy island is offshore as well... Check location of Williamson airport and Samuel hill in relation to Bom image above of cat 5 marker 10am...
Even Dvorak T number 7, 7.5 and 8 does not correspond with marcia....

http://en.wikipedia.org/wiki/Dvorak_technique

freeride76's picture
freeride76's picture
freeride76 Sunday, 22 Feb 2015 at 7:47pm

I think they'll retro-fit Marcia as a Cat4 or even 3 in due course.

fitzroy-21's picture
fitzroy-21's picture
fitzroy-21 Sunday, 22 Feb 2015 at 8:31pm

Big problem is the"boy who cried wolf" syndrome. Everyone is prepared/expecting something severe. Even the new premier kept saying this is going to be "catastrophic".
Yes it was bad, but it wasn't Tracey or Yasi. People will become numb to the hype and then........... bang.

Blowin's picture
Blowin's picture
Blowin Sunday, 22 Feb 2015 at 9:50pm

Wait till panic merchants start linking this regulation storm with relatively minimal impact to the imminent doom of mankind.

donweather's picture
donweather's picture
donweather Monday, 23 Feb 2015 at 8:35am

Major wash throughs at the super wank this morning. Looks like more sand has been deposited in the middle of the bay. WSL/quiky must be spewing!!!

Even kirra has wash throughs this morning.

freeride76's picture
freeride76's picture
freeride76 Monday, 23 Feb 2015 at 9:00am

did you go see it Don?
Or was that on the cams?

donweather's picture
donweather's picture
donweather Monday, 23 Feb 2015 at 1:49pm

Cams Steve. But I'm pretty sure you don't need to be there in person to witness a wash through?

seaman-staines's picture
seaman-staines's picture
seaman-staines Monday, 23 Feb 2015 at 9:35am

Last night was still plenty of sand behind the rock, some real death pits rolling through. There was a lot of sand in the middle of the bay but wide enough not to affect the point, well it was shadowing Greenmount a bit. There were no major gaps in the bank all the way to Kirra which was looking as Kirra like as I have seen it in the last 10 years or so. There was some water moving though, arm killing sweep.

Sheepdog's picture
Sheepdog's picture
Sheepdog Monday, 23 Feb 2015 at 9:57am

10am feb 20...... Marcia graded as cat 5 (see image above)

position - "within 9km of 22.8 degrees South 150.5 degrees East"

position Williamson bom - 22.47s - 150.8 e

mean distance - eye of marcia to williamson - 49km

max hpa reading at williamson, 10.00am- 992.4hpa

hpa needed for cat 5 - 930hpa or below.......

Too caught up in "the event" at the time to notice....
If it is not adjusted by bom, I call bullshit on BOM historical data, which has implications in other fields eg - insurance companies, building standards...
Expect Insurance companies to take a serious look at "Dvorak" some time in the future... Housing Damage currently thought to be done by cat 5... But it was strong cat 3/ low4.... Implications in building standards....

donweather's picture
donweather's picture
donweather Monday, 23 Feb 2015 at 1:52pm

" Housing Damage currently thought to be done by cat 5... But it was strong cat 3/ low4.... Implications in building standards...."

From what I've seen SD, the majority of damaged property was the older style buildings/dwellings. These would have been built pre-updated cyclone building standards and thus, very easily damaged by a high Cat 3/low Cat 4 wind gust.

freeride76's picture
freeride76's picture
freeride76 Monday, 23 Feb 2015 at 11:09am

Ben, any response forthcoming on the continuing nonsense that is the Ballina report?

Do you stand by it?

I

thermalben's picture
thermalben's picture
thermalben Monday, 23 Feb 2015 at 11:17am

Just because I don't publicly comment on something doesn't mean that things aren't going on behind the scenes. Yes, the weekend reports weren't good, and yes, we're doing something about it.

lolo's picture
lolo's picture
lolo Monday, 23 Feb 2015 at 2:09pm

Sheepdog,

Here's a pretty thorough write up of Marcia re strength/category etc from the guys at Oz Cyclone Chasers who were in Yepoon when it hit.

" There seems to be alot of discussion on our page and many other pages, with people questioning the intensity of Severe Tropical Cyclone Marcia upon its landfall.

Key Points
- DAMAGE MUCH WORSE THAN FIRST FIRST EXPECTED BY AUTHORITIES
- Up to 750 HOMES AND BUISNESSES HAVE SUFFERED STRUCTURAL DAMAGE
- 50 HOMES IN THE YEPPOON AREA ARE UNLIVABLE
- REGIONS DECLARED DISASTER ZONES

Severe Tropical Cyclone Marcia made its landfall around Shoalwater Bay on friday morning as a Category 5 system. The closest weather station to the landfall point was Samuel Hill. Marcia made landfall in a remotely populated area, and in an area that is very hard to access for the public!

On this landfall point, Yeppoon was never going to receive Category 5 wind gusts, and it was highly unlikely that Rockhampton was going to receive wind gusts that would be close to a severe system.

Tropical cyclones require warm ocean heat content to intensify and to maintain strength. Many factors impact how fast a tropical cyclone weakens over land. Mountain Ranges can weaken the centres of Tropical Cyclones very quickly! While flat land and deltas can often weaken the systems at a much slower rate, thus holding more intensity as they progress inland.

The Bureau Of Meteorology categorises Cyclone Strength usually by the means of Satellite Presentation and by Satellite documentation of surface winds via satellite passes. Especially when the system is intensifying over the ocean where no automatic weather stations are located! These satellite passes are very accurate, and Severe Tropical Cyclone Marcia was MOST DEFINITELY showing us a very tight, small and INTENSE inner core prior to landfall. In fact the inmer core was so strong, That it was likely even a Category 4 hurricane on the american scale.

The satellite presentation was so intense, that the inner core was likely just as strong as Tropical Cyclone Yasi. ( Cyclone Yasi hit populated areas, hence more damage, to the people who want to argue on our site about which system was worse . Yasi also had a massive gigantic core that resembled a Large intense Hurricane Like hurricane Ike )

Okay, so....Samuel hill recorded a maximum gust of 170kmhr as Marcia moved to the Locations West. Small midget tropical cyclones such as Marcia contain there MAXIMUM WINDS in a VERY TIGHT BAND around the eye. These maximum winds can sometimes only extend outward only a few Kilometres. Yes! Samuel hill went through the eyewall, however it was still around 10km from the most inner part of the eyewall which would have contained the strongest wind gusts.

As Tropical cyclones move inland, the winds that whip right of the ocean become disrupted due to frictional effects from trees, buildings, mountains etc. Samuel Hills observations most definatly would have been affected by frictional effects as they are located 15-20km inland. This is why Oz Cyclone Chasers do our best at getting to the coast, so we can experience the full strength wind gusts with little or no frictional effects.

As STC Marcia moved south, the town of yeppoon then went through the SE, East and NE eyewall. Yeppoon missed the inner eyewall, however being on the coast, Yeppoon itself was exposed to very intense wind gusts that will likely see the Town itself in Scientific Reports having experienced a MID CATEGORY 3 system. Many houses have complete structural failure, especially those located on hilly locations throughout the town.

The Eyewall in Yeppoon was very intense, and was definatly the most intense eyewall that we have chased and been inside of. We were not suprised with how much damage was around yeppoon and surrounding areas. There was alot of house debris flying through the air past us while we observed the strongest winds between 12-1230pm.

We just want people to realise that these systems weaken very quickly, and on the ground Automatic Weather Stations seem to never catch the best winds these systems seem to offer in our country. Thats why we do what we do, and we have taken some VERY INTERESTING data in Yeppoon.

There is no doubt in our minds that Severe Tropical Cyclone was a very intense system, and we are very confident that agencies will find it was a high 4 or LOW 5 on landfall.

Sorry for getting carried away smile emoticon

Heres a photo of our motel in Yeppoon, at some point during the passage of the system, Something speared through the roof and exited back out leaving a hole that you could see the sky through. Our motel was made out of concrete and we could feel it moving...

Showing the true power of this storm....

Thanks folks!"

Sheepdog's picture
Sheepdog's picture
Sheepdog Monday, 23 Feb 2015 at 3:50pm

Thanks, lolo... But already got that in my facebook feed.... The thing is, you did not post the very first line...... The headline.... The meaning behind the whole post...
I'm not saying this was deliberate on your behalf... I often miss a line or two when copying and pasting...

The headline was - "Thats it, something has to be said as all I am reading is ALOT of misinterpretation on how fast Tropical Cyclones Weaken over land"..

So the whole article was in relation to how fast a cyclone can weaken over land....

Sheepdog's picture
Sheepdog's picture
Sheepdog Tuesday, 24 Feb 2015 at 9:34am

Exactly..... I call bullshit....... Cheers, coupla......