Sunday, December 21, 2014

12 21 14 morning call

4am main swell buoy readings:

5.2ft @ 19s from 286° (WNW)
4.7ft @ 9s from 127° (ESE)
4.4ft @ 12s from 309° (WNW)
3.5ft @ 12s from 313° (NW)
1.5ft @ 20s from 305° (WNW)
1.4ft @ 5s from 45° (NE)
1.4ft @ 9s from 356° (N)

Maui north shore (indicative of what's in the water on Maui's north shore)
5.4ft @ 9s from 77° (ENE)
3.3ft @ 12s from 336° (NNW)
1.7ft @ 5s from 78° (ENE)

West lanai Maui north shore (indicative of what's in the water on Maui's south shore)
1.7ft @ 15s from 202° (SSW)
1.3ft @ 9s from 192° (SSW)
1.1ft @ 8s from 182° (S)
1.1ft @ 12s from 256° (WSW)
It's all about the buoys today. Read the measurements above, before reading below, please.
Below is the graph of the NW one that shows how the new swell started to pick up during last night (dark blue line).

20s travel fast, so we actually can see something already at the Waimea buoy (light blue line in the graph below).

I'm gonna use the graph above to show you why you should not check the buoys on the NOAA websites, which readings I report below. There are no sign of anything with period longer than 13s, so if you only look at that, you would think the swell is not even in the water.

The reason is that the table below only reports ONE swell. It's a little bit like checking the wave forecast on windguru: one ONE swell is reported, the one with the biggest size, regardless of the period.
Somewhere on the NOAA website though, there's the info of the energy distribution per period and what Surfline does (and plenty other websites, I'm sure), is that they analize that information and break it down per single swell.
No go back quickly at the waimea graph above.
See the black thick line? That's the (only) size you would gather by reading the NOAA readings.
Look how much smaller the 20s swell is compared to that.
In other words, the NOAA way of presenting the buoy readings CAN be extremely misleading.
I say CAN, because it's not always like that. When there's only one swell in the water or when one is WAY bigger than the other ones, then the NOAA reading can be ok.
This might happen tomorrow for example, when this big swell will have completely filled in.

Smarty pants they call me... smarty pants I feel.
As a matter of fact, I'm not even done.
Let's look at the directions now: 286 at the NW, 305 at the Waimea, nothing still at the Maui buoy.
But directions like that get "influenced" greatly by Molokai and all the other upstream islands.
The influence depends on the period. As I was saying a couple of days ago, the longer the period, the more the waves have the ability of refracting.
But while Pipeline was an example of concave refraction in which the energy of the wave gets focused on a shallow spot in front of it, wrapping around a point of land is an example of convex refraction and the energy of the wave gets defocused and spreads (wraps) around the point.
That's why point breaks are usually fun, wally but not too powerful waves (don't be fooled by waves like honolua, because yes it is a point break, but it also has reef underneath it's both a point and reef break!).

All this to say that:
- yes, we are going to see waves from this swell in Maui, but for sure they are not going to be as powerful as they will be in Kauai
- in the morning there will be absolutely no waves from this swell in Maui. It's more like an afternoon thing and the more east you go on the north shore, the better the size
- the direction will be quite west, but there is no chance that we're gonna see 286 at the maui buoy. That would mean that someone is generating waves outside the Kahului harbor! :)
- there is a chance of waves in Kihei/Wailea. I'm definitely not an expert of this coast, but I know that westerly swells can hit there.

The other relevant thing to say about today is the beautiful lack of wind of any kind all day.
Check the wind map below. One high is about to replace the other. In the meantime today it's calm, but as soon as the front between the two highs hits, the wind will turn northerly and stay like that for a week! And I don't need to say how bad that is for the waves on the north shore. So save some money for the gas, there will be some driving to be done next week.
Thanks for reading all this. Please make an effort to spread the word about this blog at the beach, because I'll only do this this winter if I don't see the numbers of readers growing. Thanks.

Have fun in the sun everyone!

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