Wednesday, December 16, 2009

December 9th-10th WNW-NW swell – After-action results

So I have been going over the survey of the WNW-NW swell that hit Dec 9-10th, compiling the answers, and just generally absorbing the information that you guys were kind enough to pass along, (which actually turned out to be a lot of really cool stuff). From a purely forecast-feedback standpoint this survey has been a great resource and has provided some solid insight that will help me refine future forecasts, which hopefully will help you guys get more waves.

Now after a couple of days of sorting it out, (and by sorting it out I mean being distracted by my usual ADD, playing Super Mario Bros.wii with my 4 year old, and having my home office rendered un-useable by my dog’s gas…which is no joke), I think I have it in a cool format where I can share it with you guys.

The goal of this breakdown isn’t so much about giving away a ton of specific information on surf spots, but more about sharing how our little community perceived and interacted with this WNW-NW swell. Did it live up to the hype? How did it hit the different regions? Did we have fun with this one or was it too much swell energy? There are a lot of interesting answers.

One thing to keep in mind when we look at some of the data is the perception of wave size. Wave-size is so subjective that it makes you want to pull your hair out sometimes. It is such a personal thing that you will almost never get the same answer from different surfers…you can take 10-guys down to the beach, or show them a video, or whatever, and as the swell gets bigger you will get 10 different answers to the basic question of “how big is it?”.

A little further down in this report you will see some “average” wave sizes for each region, remember these heights are being averaged from your responses and since one person’s 5-foot wave doesn’t always match up with your idea of a 5-foot wave, they should be taken with a grain of salt.

Ok now with that little caveat out of the way…let’s go over some of the highlights of the survey.

We had about 350+ people fill out the survey…with about a 50/50 split reporting either on Wednesday’s or Thursday’s surf.

About the swell
Almost everyone felt that the swell did not live up to the forecasts, and that it arrived early, peaking on Wednesday, before dropping on Thursday.

The general consensus was that while the surf was good, it wasn’t as big as expected, and the crowds were a bit heavy in anticipation of larger surf.

Also, and this is more of a personal observation, it sounded like the buzz about the swell got out Wednesday night as the first reports started filtering to everyone, and the combo of dropping sizes and a fat morning tide made for a disappointing surf check early on Thursday.

On Wednesday, December 9th, most of you thought the surf was definitely above average…here is how it was rated in the survey.

Excellent - 3.8%
Good to Excellent - 20.0%
Good - 26.3%
Fair to Good - 23.8%
Fair - 15.6%
Poor to Fair - 6.9%
Poor - 1.9%
It sucked - 1.9%

On Thursday, December 10th, the surf continued to be rated above average…even edging a bit further into the “good” range than Wednesday.

Excellent - 8.4%
Good to Excellent - 17.8%
Good - 28.7%
Fair to Good - 22.3%
Fair - 13.9%
Poor to Fair - 5.4%
Poor - 2.5%
It sucked - 1.0%

Highlights about you guys in general
(to sort of set the stage on your surf responses)

About 75% of you rode a shortboard… and about 4% of you apparently were dolphins, which if you know my sordid history with flipper, does not put you on my “warm-fuzzy” feeling list. Here check out the chart…I think that I make myself pretty clear.

The majority of the survey responses were for spots in North LA, Orange County, and San Diego.

Santa Barbara and Ventura had the fewest responses.

Across both days bout 70% of you surfed in the morning (from the Dawn Patrol up through Brunch).

You guys spread out the spots pretty well, there didn’t seem to be an overwhelming preference for any particular break.

We all thought it was f-ing cold in the morning on both days.

You had fun…an overwhelming 93% percent said so.

Adding the optional “comments” section at the end was a good choice on my part…almost everyone that took the time to add additional comments provided some awesome feedback. Lots of great stories, good descriptions of the surf, and some classic comedy from you guys. This was easily my favorite part of going through the data.

Let's move on to the wave/swell details.

Wednesday December 9th, 2009

Swell Details
The new WNW-NW swell (280-300) was already showing pretty well early on Wednesday. It had actually started to pulse up in select spots in Ventura on Tuesday evening, and it pretty much peaked in that area through Wednesday morning. The other, more southerly regions, had the swell coming on strong through the morning but according to buoys it peaked more around midday. The swell periods were very long compared to average WNW-NW swells, arriving initially at 22-24 second periods, and with wave heights peaking in the 18-20 second range.

The CDIP analysis “nowcast” model had the WNW’er peaking with nearly 10-11’ of deepwater energy, but the model was being initialized off of the Harvest Buoy that was both closer and much more exposed to the swell’s energy due to its position ESE of Point Conception (and out of most of the swell shadowing that occurs in Socal’s actual surf zones).

Wednesday’s Surf Reported in the Survey
Here are the Regional CDIP “nowcasts” with the average morning and afternoon wave heights reported for each area.

And here is a graph with those wave heights compared against each other…as you can see much of Wednesday’s morning size was concentrated in the North…but filled in more through the afternoon.

Thursday December 10th, 2009

Swell Details
By Thursday morning the swell according to our nearshore buoys had dropped off quite a bit, losing as much as 3-4’ feet of size on some of the more “exposed” buoys. The swell had also started to slow down with most of the energy now coming in at 15-16 second periods, which meant that not only did the swell lose some size but it was losing the underlying power as well. It also changed how the swell refracted and bent compared to Wednesday, which means that the “focal” spots changed from the long-period standouts to breaks that do better on the medium-long period energy. The swell also did dip a little in swell direction…shifting a little more W-WNW in its approach, but the majority of the energy continued to push in from the NW (290-300) swell angle. These changes generally increased how many spots saw the swell but it hacked out a considerable amount of size from the bigger sets.

Thursday’s Surf Reported in the Survey

Here are the Regional CDIP “nowcasts” with the average morning and afternoon wave heights reported for each area.

And here are Thursday’s wave heights laid out in graph form so you can compare each region. Definite drop off from Wednesday’s sizes, and even less on tap through the afternoon.

Some Final Thoughts on this swell
I was looking back through my forecasts for the days leading up to this WNW swell and they matched up ok/fair with what we actually saw surfwise (or at least what was reported in the survey), which to me means that my forecasts could have been dialed in a bit better.

I expected the swell to show more size in the mid-long period range, but instead it peaked way up in the long-period range, which threw off the timing (Long-period swells travel much faster than short-period ones, and decay less as well). Sizewise it was bigger on Wednesday while I was expecting the bigger day to be on Thursday.

Not to get too weather nerdy (sorry can’t help it)…but in hindsight I can see where my forecast, and the various swell models, ran into issues. Check it out…

Obviously this is a much simplified version of what happened, but the two arrows sum it up pretty well. Basically the storm’s fetch was forecast to push further east before curving northward…the forecast model had it traveling quite a ways than it actually did…and that missing time of “wind over water” gutted the medium period portion of the swell.

This is actually a problem that crops up from time to time with both the GFS and the NOGAPs models, they have trouble estimating wind strength in those mid-latitudes, particularly when there is a lot of extra-tropical energy involved. Since the swell-models are driven by the wind/weather models, it becomes a case of crap-data-in/crap-data-out…which sucks. You can lessen the impact of the models’ weakness by getting actual measured satellite data, but for this storm the QuikSCAT satellite, which was a great one for getting wind information, decided to stop working and is probably drifting off into deep space at this point (I am not really kidding on that last part).

Anyhoo…enough of my problems…at the end of the day some of you guys had trouble finding the sort of waves that you were expecting from my forecasts, (I am sure with some always lovely help from the various surf-forecast hype machine/giant game of Telephone that big swells have become over the last several years), which means that this little ol’ forecast could be tightened up and I can work on being a little clearer on what we can really expect when the swells actually arrive.

Thanks again for the survey responses…hopefully this little breakdown on the swell will help you guys score a few more waves next time a decent sized winter swell brews up.


Adam Wright


Anonymous said...

Very nutty stuff. Coconutz!!

Anonymous said...

Thanks Adam, that was fun.

From a psychological angle, how did the "fish stories" compare to the objective wave height data? Were they at least correlated?

Also, what was the greatest variation you saw of the eyewitness reports? Were people generally in agreement with one another at a given spot, or was the data too sparse to tell?

Anonymous said...

You could make your forecasts more accurate? That is all we need. More precision to maximize bodies in the water. good enough as it is, people need to figure some things on their own.

namotuman said...

what about the unlucky folks that only got to surf the scraps on friday?....actually, friday a.m. had a decent window of conditions in the 7-10am period with still some good ones in the shoulder occasional head high range (south o.c.)....

surf school los angeles said...

Hahaha. That's cute. The "you are dead to me" sign.

Anonymous said...

here it is! good.

well at least you didn't call for the swell of the decade! way short of that. thanks for the results!

Anonymous said...

Thank you,
that's why they call me Coco, Nutz or Coconutz!
This swell was a real fickle lady on the rag. If they named these storms like hurricanes, this one would be LINDSAY LOHAN!
Like I said a real asswell!
p.(no M!)s.
It's real nice up here in tahoe.
Monday was the day, hopefully tomorrow again.

Anonymous said...

Awesome, thanks Adam! How about putting up a few of the best submitted stories?