Monday, December 22, 2014

12 22 14 morning call

4am main swell buoy readings:

11.2ft @ 16s from 281° (WNW)
8.1ft @ 10s from 329° (NW)
3.5ft @ 8s from 336° (NNW)

9ft @ 17s from 312° (NW)
1.8ft @ 9s from 350° (N)
1.4ft @ 11s from 320° (NW)
1ft @ 5s from 50° (NE)

Maui north shore (indicative of what's in the water on Maui's north shore)
    6.7ft @ 17s from 317° (NW)
4.2ft @ 9s from 74° (ENE)
3.5ft @ 11s from 332° (NNW)

West lanai Maui north shore (indicative of what's in the water on Maui's south shore)
    3.7ft @ 17s from 285° (WNW)
1.4ft @ 9s from 194° (SSW)

Great post today, lots of stuff to talk about.
Once again, you guys need to carefully read the buoys readings above to understand what I'm going to say.
Let's start from three buoys together: NW, Waimea and Maui.
First notice that the scale for the NW graph is different (20 feet top of the Y axis, versus 12 of the other two). Then notice how Waimea (and consequently also Maui) hasn't peaked yet.
And lastly notice how the direction of the swell at the NW buoy went even more west in the last few hours (red arrow pointing at the blue line). I do remember the fetch doing that, so no surprise there (for me at least...).
That direction change WILL NOT be reflected by the directions we'll read at the Maui buoy later in this swell. Once again, the Maui buoy can't register anything more west than around 310, unless a meteor lands in the water in Waiehu or outside the Kahului harbor.
I hope this will be more clear after I discuss the next picture.
Now, that's some good info below. Let's look at the north section of the pic below first. I drew two lines that show the directions of the swells picked by the Waimea (312) and the Maui (317) buoys.
Don't forget that the original direction of the swell before it gets refracted by Kauai AND all the upstream uninhabited islands that we all forget about, is around 290.
See why the Maui buoy won't show anything more west than around 310? Because there's the West Maui Mountain and Molokai! So what is a change of 10 degrees more west of the original swell going to do on the north shore? The direction will still be more than 310, but the energy will be less.
Don't forget, the more a wave gets convexly refracted (or defocused), the more energy it loses.
Also, the period of the swell will go down and the lines will be refracted less. So don't be surprised if tomorrow it's going to be a smaller than today.

But now let's look at the southern part of the pic.
The Lanai buoy is reading 3.7ft @ 17s from 285° and I drew a line from that direction.
What is totally unknown is how much that direction is going to change after the refraction around the southern tip of Lanai. If the direction changes to straight west (270), the whole Kihei coast will have waves. But we have no means to predict that. That's why you guys that live over there should write down direction and sizes and build your own database of observations... yeah, right.
And why is the size only 3.7f I hear you saying?
Well that's because the swell has already been refracted by the southern tips of Niihau AND all the other upstream islands and that's what it is. Don't forget that the bulk of the swell will move north of the islands. Go down a few posts if you don't remember the position of the huge fetch that generated this large swell.

Uff, that was a lot of explaining. I hope you guys will remember this post. I should actually label it "refraction" so that it will be easy to find for future reference.
The really good news is that the dreadful onshore wind won't hit until tomorrow! Hurray!
But once it will hit, the waves will be ruined for quite a while. Look at the fetch of northerly wind I circled in the picture below and imagine how much chop and short period waves from the north that thing is going to send....


Yesterday two persons in the lineup thanked me for this blog. Two ladies, actually, one of which even blew me a kiss for that. That's a way of motivating me. Blew me kisses if you like this blog! If you're a guy, just say thanks.
And spread the word in the lineup, on the beach, on social media, etc. Once again, this might be a one season only experiment if the number of readers doesn't increase significantly.

And since I'm talking to my readers, here's the most common question I get:"why don't you clearly write down where to go surf?"
The answer is:
- well first sometimes I don't even know and I need to check Hookipa first (that's when I post the photo)
- even if I know where I'm gonna go, I don't want anybody to join me because it read it on the blog
- and even if I know where to go surf, that's my personal choice based on my personal skill and my personal preferences. What the hell a reader like Yuri Soledade cares where I'm going surfing? He's probably going to paddle Jaws this morning! But he does read my blog because he finds it interesting (thanks for that!).
You guys should do the same. Use the info you read here and build your own knowledge and take your own decision.

Have fun in the sun everyone!

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