MId Coast vs North Coast KI

funpeeler's picture
funpeeler started the topic in Wednesday, 13 Nov 2013 at 8:13pm

Gotta say I am a bit confused as to how the forecast models work and are calibrateed with respect to nearby areas..

Going to KI for the next few days and was planning not to take a board. Howling southerlies and flat Mid Coast mean that North Coast KI is the only option but with no swell I will be fishing.

But...

The KI forecast is telling me that the waves will be waist to shoulder high on the North Coast.. Do I pack the mal? I cant understand how North Coast KI has clean offshore waves when the mid is flat.

Cheers

thermalben's picture
thermalben's picture
thermalben commented Thursday, 14 Nov 2013 at 6:05am

That's a fair point FP. We've spent the bulk of our time calibrating the model against our primary forecast locations (ie where we previously used to do manual forecasts, because this is where we receive daily verification from) so there are some locations - such as Kangaroo Island - where we've had limited feedback. So now that we're live, we are in a phase where we're trying to fine tune these areas as we start to receive broader verification.

I was on KI a few months back and found that the model got the trends bang on (arrival, peak, easing etc) but overcalled in some instances. This was mainly for the South and West Coasts, however I ventured to the North Coast one day and the model got it bang on.

A quick look at the data suggests it might be running a smidge high for the next couple of days, but Craig's in a better position to assess this (so I'll wait for him to comment). But there is definitely a small groundswell running so there should be some fun peelers (boom tish! sorry.. couldn't resist).

Our wave model is divided up into eight global forecast region types, each of which has a different algorithm to predict the eventual surf heights. My feeling is that we'll probably switch to a different forecast region for all three KI locations - and possibly some other SA regions such as Yorkes - as it does seem to be overcooking surf heights.

Would love some verification of the surf size when you're over there - just email through if you'd prefer to keep it quiet.

Craig's picture
Craig's picture
Craig commented Thursday, 14 Nov 2013 at 8:28am

Ben's explained it best and we will probably adjust the whole of KI, but regarding today's swell, I would be expecting really inconsistent 2ft waves on KI's North Coast, with the odd bigger one on the incoming tide. 

There are 1ft sets on the Mid Coast, so 2-3ft on KI's North Coast wouldn't be a stretch, but let us know how it performs.

Craig's picture
Craig's picture
Craig commented Thursday, 14 Nov 2013 at 11:42am

Swell is bang on forecast now, with tiny but clean 1ft waves on the Mid, look at those lines!!

snickers's picture
snickers's picture
snickers commented Thursday, 14 Nov 2013 at 1:42pm

thermalben wrote:

Our wave model is divided up into eight global forecast region types, each of which has a different algorithm to predict the eventual surf heights. My feeling is that we'll probably switch to a different forecast region for all three KI locations - and possibly some other SA regions such as Yorkes - as it does seem to be overcooking surf heights.

Would love some verification of the surf size when you're over there - just email through if you'd prefer to keep it quiet.

Yorkes height was definitely over-cooked last weekend. 4-5 ft according to your forecast, but actual height on open beaches was more like 2-3. You might want to look at the tide chart and compare with the bom.

barley's picture
barley's picture
barley commented Thursday, 14 Nov 2013 at 1:53pm

Yorkes is quite often overhyped/overscored..most of the peaks in the swell come overnight so when Smellnet call 6 it can quite often be 3-4..or there is a 6/12hr difference either way of what you guys call..Aah the look of disappointment when crew rock up expecting it to be pumping and are just met with average..thats the problem with relying on computer models to 'forecast' swell events..In the end its only guesstimating!!
Nice day on the mid though!! cool shots

trolleyboy's picture
trolleyboy's picture
trolleyboy commented Thursday, 14 Nov 2013 at 1:58pm

barley wrote: most of the peaks in the swell come overnight

You don't know much about weather do you?

thermalben's picture
thermalben's picture
thermalben commented Thursday, 14 Nov 2013 at 2:03pm

snickers wrote: Yorkes height was definitely over-cooked last weekend. 4-5 ft according to your forecast, but actual height on open beaches was more like 2-3. You might want to look at the tide chart and compare with the bom.

Thanks for the verification - I've thought it's been slightly overcooking the Yorkes figures for some time but we wanted to get some feedback before making any changes.

For what it's worth, we've had a bunch of reports from Yorkes locals and regulars over the last few weeks which have shown that the size at Ethels/West Cape is reasonably close to the forecast. However, because hardly anyone surfs these spots when it's bigger than 4ft, if the surf forecast is 6ft or greater then people are surfing other protected spots. So, I'm leaning towards recalibrating the forecast to the broader range of surf spots in the area, rather than just the 'swell magnets'.

As for the tide chart - that's actually a display issue. The data is correct (it's pulled from the BOM's Pt Lincoln feed, and then calibrated for Pondi) - however it's not showing up in the right areas on the forecast chart. We've got this lodged as a support ticket to be fixed ASAP.

barley's picture
barley's picture
barley commented Thursday, 14 Nov 2013 at 3:47pm

@trolleyboy..nah, nothing.

thermalben's picture
thermalben's picture
thermalben commented Friday, 15 Nov 2013 at 11:06am

Worth pulling up some of the current SA forecasts as I reckon our model has done pretty well over the last few days, especially by comparison with some of the other websites. Small long range groundswells are difficult to resolve at the best of times and I reckon we've got the algorithm very close for the Mid Coast.

For yesterday and today, our Mid Coast forecast has had a small persistent groundswell close to one foot (confirmed by many sources and surfcam vision). But, MagicSeaweed are forecasting 4-6ft at "Triggs Beach" today (beach?!).

Even allowing for the fact that MSW forecasts are face feet (we use 'surfers feet', which would translate their numbers to 2-3ft), this is a gross overcall by their system.

thermalben's picture
thermalben's picture
thermalben commented Friday, 15 Nov 2013 at 11:12am

Even better - their West Cape forecast is calling smaller surf than on the Mid today!

Not sure if anyone's over there today but I reckon our forecast of 3-5ft is probably a little overcooked but wouldn't be far off 3ft to maybe 4ft (would love some verification). MSW's 3-4ft forecast (face feet) for West Cape is only 1-2ft in surfers feet - it'd have to be much bigger than that. 


barley's picture
barley's picture
barley commented Friday, 15 Nov 2013 at 12:08pm

spot on Ben..but no real banks and a bit tiny for everwhere else :)..offshore for TOS but friggn small...What do you think about the summer season?IMO we could be in for a summer of very few swells..do you see anything to support this either way?seems like the weather paterns have changed and we could get the big blocking highs?maybe a wet east coast again?as in really wet!

yorkessurfer's picture
yorkessurfer's picture
yorkessurfer commented Friday, 15 Nov 2013 at 12:14pm

I've just been over on the far west coast of SA for the week at that certain beach that we dare not mention and despite a very average swell forcast we got waves every morning and yesterday was extremely nice 4+ft, morning glass and four of us out. SN call for size was bang on although local wind variability meant the SE winds were light to non existent every morning but blew up like clockwork every day at around 10am. All in all a successful mission;)

thermalben's picture
thermalben's picture
thermalben commented Friday, 15 Nov 2013 at 12:38pm

barley wrote: spot on Ben..but no real banks and a bit tiny for everwhere else :)..offshore for TOS but friggn small...What do you think about the summer season?IMO we could be in for a summer of very few swells..do you see anything to support this either way?seems like the weather paterns have changed and we could get the big blocking highs?maybe a wet east coast again?as in really wet!

Unfortunately I don't have any evidence either way - really not sure what this summer will bring surf wise. We're focuing some of our research into this area though, so hopefully we'll be able to draw some correlations over the coming years. But for now the 16 day forecast is your best heads up :D

thermalben's picture
thermalben's picture
thermalben commented Friday, 15 Nov 2013 at 12:39pm

yorkessurfer wrote: I've just been over on the far west coast of SA for the week at that certain beach that we dare not mention and despite a very average swell forcast we got waves every morning and yesterday was extremely nice 4+ft, morning glass and four of us out. SN call for size was bang on although local wind variability meant the SE winds were light to non existent every morning but blew up like clockwork every day at around 10am. All in all a successful mission;)
Unreal YS.. great feedback. We're working on an improvement with the wind forecast at the moment which should iron out those small inconsistencies during variable periods.
maddogmorley's picture
maddogmorley's picture
maddogmorley commented Friday, 15 Nov 2013 at 1:02pm

I was at Cactus from 1/11 to 10/11 and your forecast was pretty spot on there too Ben - especially for Caves - as you know the swell needs to refract for Caccy so wasn't as big as forecast which was expected.

Craig's picture
Craig's picture
Craig commented Friday, 15 Nov 2013 at 1:24pm

Awesome MD, yeah it is for exposed spots like you mentioned rather than the more protected breaks. I was around the area earlier this year under a larger W/SW groundswell when we were still testing the new forecast system and it picked it perfectly as well.

snickers's picture
snickers's picture
snickers commented Friday, 15 Nov 2013 at 4:50pm

thermalben wrote:
For what it's worth, we've had a bunch of reports from Yorkes locals and regulars over the last few weeks which have shown that the size at Ethels/West Cape is reasonably close to the forecast. However, because hardly anyone surfs these spots when it's bigger than 4ft, if the surf forecast is 6ft or greater then people are surfing other protected spots. So, I'm leaning towards recalibrating the forecast to the broader range of surf spots in the area, rather than just the 'swell magnets'.

As for the tide chart - that's actually a display issue. The data is correct (it's pulled from the BOM's Pt Lincoln feed, and then calibrated for Pondi) - however it's not showing up in the right areas on the forecast chart. We've got this lodged as a support ticket to be fixed ASAP.

Thanks for clearing up the tide chart issue - I didn't look at the numbers, just the graph & forecast chart and noticed it was way off what the bom had.

The 2-3ft I mentioned was Ethels/West Cape on sun (although only viewed from the cliffs) . Dalys was 1-2ft and there was crew out to confirm that. Everywhere else was dead flat. Maybe the swell direction made it smaller than your call? dunno.

I was wondering what you were calibrating the surf size against. If you recalibrate, what do you use as the yardstick, given there are so many spots of different sizes in the same swell.

Also, no argument that your forecasts are better than others, eg. MSW. Just helping fine tune the output.

thermalben's picture
thermalben's picture
thermalben commented Friday, 15 Nov 2013 at 4:54pm

Snickers, we're calibrating against reports from surfers we know personally, or speak to regularly. Size wise, we're using 'surfers feet' as our measuring size - that is 3ft's about head high and so on.

Each forecast is currently calibrated for 'exposed' locations. So in the case of Yorkes, it'd be West Cape and Ethels. Then if you use your personal experience, you'll know which breaks along the peninsula fare best under west, southwest and south swell events.

BTW, Dalys being surfed at 1-2ft? Thought it would have barely been rideable at that size (waist high or so). In my experience - and to be honest, Dalys isn't high on my list when I'm at Yorkes - when it's 2-3ft there's sometimes a fun short right off the inside reef breaking into the point, and a slightly longer but very fat left. Above 3ft the lefts start to become a little more interesting; above 4-5ft it breaks on second reef, then above 8ft it breaks on third reef.

Thanks for the feedback though - this is all invaluable information and will assist in making our forecast service even more accurate.

snickers's picture
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snickers commented Friday, 15 Nov 2013 at 6:01pm

Fair enough mate. I'm using the same measurements so we are on the same page here. There was no one out at Ethels/West cape which is why I say that I'm only judging from what I saw from the cliffs, but I know those places well to enough to say that I'm confident I have it right.

There were a few desperados trying to surf dalys. I don't think I saw any turns though - just a drop and a pump as the wave mushed out. Size wise it was waist to shoulder high at takeoff but quickly became knee high. Call that as you will. Likewise, it's not high on my list - I don't bother with it unless its 2nd reef.

thermalben's picture
thermalben's picture
thermalben commented Friday, 15 Nov 2013 at 6:15pm

Unreal.. thanks snickers. Really appreciate your info.

BTW, we've got an eternal debate going on here in the office as to whether the surf looks bigger or smaller from the vantage point of a high cliff. I'm gonna start a forum thread shortly to settle it for once and all!

mothart's picture
mothart's picture
mothart commented Friday, 15 Nov 2013 at 6:42pm

Always looks smaller, doesn't it?

snickers's picture
snickers's picture
snickers commented Friday, 15 Nov 2013 at 6:44pm

Good one. I'd say it looks better and gives you a better overall picture of conditions from high up. That's why everyone climbs all over the dunes to check the surf. Maybe it looks bigger if you aren't used to seeing waves from a high vantage point, but once you know a spot you adjust your interpretation based on previous experience.

maddogmorley's picture
maddogmorley's picture
maddogmorley commented Friday, 15 Nov 2013 at 7:19pm

Looks smaller for sure.....if you have adjusted your interpretation then that was because initially it looked smaller than it was - if it was the same you wouldn't have adjusted would you?

Craig's picture
Craig's picture
Craig commented Saturday, 16 Nov 2013 at 5:33pm

Yep defo smaller from the cliffs, I've had many a surf checks from above where I've thought it looked a fun size to only get out there seeing it's way bigger.

The view from above on a cliff or headland compresses the height of the face of the wave making it look smaller.

funpeeler's picture
funpeeler's picture
funpeeler commented Tuesday, 19 Nov 2013 at 1:26pm

Ben,

A bit of calibration info...

I was at Stokes on Sunday and there was a 6" low tide runner on the beach through the cave. Not surfable on a board but little kids on boogers would have been all over it.

Hey - has anyone surfed any other North Coast spots?

On Google Earth there is a perfect A-Frame peak breaking at a spot some distance to the East of Stokes. Probably private property.

Craig's picture
Craig's picture
Craig commented Tuesday, 19 Nov 2013 at 1:57pm

Wasn't much swell around on Sunday funpeeler, you remember what the forecast was? Cheers!

thermalben's picture
thermalben's picture
thermalben commented Tuesday, 19 Nov 2013 at 2:08pm

Thanks FP. The weekend forecast was (for KI North Coast, off the top of my head) just foot or so - I'm pretty sure the 'waist to shoulder high' forecast was for the Thursday and possibly Friday. In the future, if you've got internet access please screen grab the forecast for easy reference.

I'm not especially familiar with the KI coast (north, south or west) outside of the obvious locations - and I'm sure there are heaps of waves if you're prepared to trudge through endless farmer paddocks. And surf by yourself too. Incredible place but jeez it's eerie in the water!

yorkessurfer's picture
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yorkessurfer commented Tuesday, 19 Nov 2013 at 2:17pm

I have surfed the peak your talking about I think funpeeler but I was working on a shark boat and jumped off the side of the boat to surf it. I was surprised the swell got that far east on the north coast. It's a strange feeling jumping off a boat like that after you have been hauling the beasts in all day. Only little ones for the fish and chip shops mind you;)

funpeeler's picture
funpeeler's picture
funpeeler commented Wednesday, 20 Nov 2013 at 3:12pm

I reckon there would be fun waves up the far end of Emu Bay on a decent swell. Can drive a car up there too. Gorgeous spot.

Craig's picture
Craig's picture
Craig commented Wednesday, 20 Nov 2013 at 5:18pm

We've just tweaked the Yorke Peninsula forecast to come more into line with what's been reported the last couple of weeks. Be good to hear how it goes YS and Barley.