Saturday 11 23 19 morning call

Remember the glassy days when Maui looked like Bali? This was just a week ago. Memphis Brown in a shot from his dad Jesse.



5am significant buoy readings and discussion.
South shore
No indication of southerly energy at the buoys, the Lahaina webcam comfirms that.

North shore
NW101
5.7ft @ 12s from 341° (NNW)

Waimea
3.6ft @ 12s from 304° (WNW)

Pauwela
7.9ft @ 9s from 61° (ENE)

4.3ft @ 13s from 325° (NW)

3.1ft @ 5s from 62° (ENE)

 

An interesting email about the buoy readings from blog reader John Bruder is reported at the end of this post, together with my comments.

The directions of the NW swell at the three buoys is largely different and I don't know how to explain that. We just focus on Pauwela and we see 8ft 9s of windswell plus 4.3ft 13s of leftover NW. Plenty rough waves on the north shore, another day of blown out surf, because of the strong easterly winds... unless you catch it in the temporary clam after a squall.

Surf Bash contest at pavilions today and tomorrow. 

Wind map at noon.

Kahului Tides
High Tide     High Tide     Low Tide     Low Tide       Sunrise   Sunset
12:35a  +2.1  11:56a  +2.0   6:19a  +0.7   6:28p  -0.2    6:43a   5:45p    

North Pacific has a pretty good NW fetch which is only partially aiming at us. Hopefully we'll get some angular spreading from the stronger fetch aiming at the Marshalls.


South Pacific has a pretty long S fetch.


Lately I've been playing with where to place the isobars. These are the same maps as above, but the isobars are on the great circle rays map on the right. I think I like this better, as you can see the wind direction better on the Windity map on the left.


Morning sky.


Here's John's email, starting with a quote from yesterday's morning call.

"The thick black line on the buoys' graph is the significant wave height (sum of all the energies on the water) and it's what you get if you check the buoys on the NOAA website."

 

 

 

 

 

 

 

I had the same understanding and when Surfline began requiring paid membership to access the buoy data I joined.  Unfortunately I find the rest of the site useless.  The forecasts aren't very accurate.  Also, the page for the buoy data sometimes doesn't load or loads very slowly.

Turns out we are wrong about the NOAA buoy data.  NOAA actually provides a decomposition that includes the two swells with the largest energy.  This is typically the primary swell and the secondary wind-wave swell.  I compared the primary swell data to what Surfline provides and they appear to be consistent.  The NOAA data is updated every 30 minutes.

For the Pauwela Buoy go to this page:

https://www.ndbc.noaa.gov/station_page.php?station=51205

Then scroll down to "Detailed Wave Summary"

MM	DD	TIME (HAST)	WVHT ft	SwH ft	SwP sec	SwD	WWH ft	WWP sec	WWD	STEEPNESS	APD sec
11	22	10:00 am	11.8	5.2	14.3	NW	10.2	8.3	ENE	STEEP	7.4
11	22	9:30 am	11.5	6.2	14.3	NW	9.8	7.7	ENE	AVERAGE	7.5
11	22	9:00 am	11.2	6.2	15.4	NW	9.5	9.1	ENE	AVERAGE	7.4
11	22	8:30 am	12.5	6.9	14.3	NW	10.5	9.1	ENE	AVERAGE	7.7
11	22	8:00 am	10.5	4.6	15.4	NW	9.5	7.7	E	STEEP	6.

SwH and SwD are the dominant primary swell height and period.

WWh and WWp correspond with the secondary swell.

Thanks a lot for the valuable contribution. Here's my reasons why I still like to be a Surfline member.

I agree that the SURF SPOTS forecasts are not very accurate. But that is true for ANY forecasting website. Nobody has a near shore model that can match the experience of the local surfers. I NEVER look at ANY SURF SPOT forecast from any website. All I need, is the open ocean forecast, which instead I find acceptably accurate. That comes mostly from the WW3 model, Surfline just puts it in a pleasant graphical form. A form that you can easily compare to what the buoys record (which is what I did yesterday and the day before). Once I know the open ocean swells height, period and direction, I immediately have an idea of the size of the waves at any spot on the island, and that is more accurate than any SURF SPOT forecast you can find online. I encourage all my readers to start doing this: you look at the buoys, you go to the beach, and you remember what you see. That's one more entry in your personal database of local knowledge.

So, even though John points out that the NOAA does show the TWO primary swells, I still like the Surfline buoy page (link n.11) better because you see them all at once. And if you want to investigate more on one particular buoy, you click on it and it shows you the graph, on which it's a lot easier to spot the trends. Unfortunately, it is true that the readings are more than one hour old and that sometimes it takes time to load.

The only other reason why I consider it worth it to pay the subscription is the 17 days long term forecast, which I use when I plan surf trips last minute.