Tuesday, May 09, 2017

Tuesday 5 9 17 morning call

A couple of sessions on the north shore yesterday ended my dry spell. Both of them were quite unsatisfactory, I'm suffering from a lack-of-wave-quality syndrome caused by the Mentawai trip. I just posted part 2 of that report, you'll find it just below this call, so you can better understand why. In the meantime, here's a shot. Nope, that's not Hookipa.

4am significant buoy readings
South shore

The surfline forecast for 8am reads 0.9f 15s, while at the same time tomorrow it reads 1.9f 14s. So it should be still early for the little south swell today. But if you are patient enough, I believe you can score a waist high set also today. That is based on the observation of the wind map of a week ago that shows a fairly large, but not particularly intense fetch.

It is also based on the observation of the Samoa buoy graph snapshot that I took on the 5th. Here's an abstract of the Buoys to Maui travel time and shadowing angles post, that shows the travel times from that buoy to us:

The Samoa buoy (S on the map, F stands for Fiji instead) is located at 14.265 S 170.494 W which is at an angle of 202 degrees SSW of Maui and at a distance of 2,222 nm. Below are the travelling times of swells coming from that direction.
20sec--30kts-- 74hrs (3days)

17sec--26kts-- 85hrs (3.5 days)

14sec--21kts--106 hrs (4.5 days)

11sec--17kts--130 hrs (5.5 days)

I circled in red the swell, the size is definitely not particularly impressive and it's going to go down a lot more during those 4.5 days of extra travel. What I honestly ignore, is how much the period grows in such time/space.

All this analysis is kinda useless (but hopefully interesting for someone), if the sun is out and you can look at the webcams. Here's a snapshots: Lahaina on the top and Hookipa on the bottom. I had to wait quite a while to catch that set.

North shore
5ft @ 8s from 352° (N)
4.3ft @ 11s from 313° (NW)
3.4ft @ 10s from 320° (NW)
4ft @ 12s from 315° (NW)
4.6ft @ 9s from 74° (ENE)
2.8ft @ 12s from 317° (NW)                      
1.6ft @ 11s from 324° (NW)
Very modest readings at Pauwela, and once again quite a big difference with our Oahu cousins. Following the path of the fetch (which you guys can check by scrolling down to the calls of the previous 3-5 days), the swell turned a little bit more north and so the refraction hypothesis is not really viable anymore. 1.2f less for 100miles/4hours of additional travel seems unrealistic. I admit I'm a bit lost. Anyway, the wind should be favorable, at least in the early morning. At 5.24am the Hookipa sensor is reading 3(1-4) from 131, which is as good as it can be. Stay tuned for the beach report for a size estimation, it should still be head high.

As far as the wind later in the day goes (or will go), here's two completely contrasting predictions.
Below is the NAM3km model as graphically expressed by the Windity (now only Windy) website. It shows plenty wind in the afternoon.

Below instead are the two models at the bottom of the Windguru page. The top one is the same NAM3km model, but it shows a different story with the trades picking up only after 6pm. The bottom one is the HRW one and it shows trades from 6am to 10am and then light south after that.
And that's why I believe that without the MC2km maps based on the much more reliable WRF model we are kind of lost in the wind department. I'll look if those maps are available somewhere else. Any help from the readers would be greatly appreciated.

Current wind map shows:
1) remote and small NW fetch
2) small windswell fetch
I put an arrow on a small local low that is responsible for shutting temporarily down the trades...

...and pulling some moisture out of the south.

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