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What's up with the Lulls on the wind graphs?

 
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hoodvista



Joined: 23 Sep 2000
Posts: 20

PostPosted: Sun Sep 04, 2016 8:16 pm    Post subject: What's up with the Lulls on the wind graphs? Reply with quote

It looks like the lulls on all the wind meter graphs are now practically touching the average readings. I sailed at Swell today and I know the wind was not that steady. Did something change?
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cgoudie1



Joined: 10 Apr 2006
Posts: 2093
Location: Killer Sturgeon Cove

PostPosted: Sun Sep 04, 2016 11:52 pm    Post subject: Re: What's up with the Lulls on the wind graphs? Reply with quote

Wondering about this myself. Same at Doug's yesterday.

-Craig

hoodvista wrote:
It looks like the lulls on all the wind meter graphs are now practically touching the average readings. I sailed at Swell today and I know the wind was not that steady. Did something change?
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ciobst



Joined: 20 Jun 2006
Posts: 13

PostPosted: Mon Sep 05, 2016 12:26 am    Post subject: Reply with quote

The wind sensor is in one spot. Today was very consistent wind, just not across the whole River. WA side was lighter till 1/3 way out where it picked up substantially, then backed off the rest of the way across. Stayed like that for hours.
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hoodvista



Joined: 23 Sep 2000
Posts: 20

PostPosted: Mon Sep 05, 2016 1:44 am    Post subject: Reply with quote

It looks like at about 7:00 AM on Thursday Sept 1st, the lulls at all sites along the river became a thing of the past. According to the charts we are now blessed with incredibly steady wind. It must have something to do with climate change.


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windfind



Joined: 18 Mar 1997
Posts: 1372

PostPosted: Mon Sep 05, 2016 10:28 am    Post subject: Reply with quote

Hi Gang,

And yesterday I was bemoaning missing an incredibly steady Hatch day due to my sprained ankle!!!

Yesterday it looked like the Hatch and Swell were mimicking a typical day at Berkeley in the Bay Area but on steroids. Berkeley often has average and lulls winds closely aligned as below.

I have informed the IT guys at our Florida & Boston offices about the lull issue. It is also appearing in the Bay Area and Southern California sensors. Given the holiday there is a chance it might not be fixed until tomorrow.

Meanwhile enjoy the illusion of steady winds.

Mike
iwindsurf.com/ikitesurf.com
Weatheflow.com



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bmmiller



Joined: 23 May 2007
Posts: 93

PostPosted: Mon Sep 05, 2016 11:38 am    Post subject: Reply with quote

Hey everyone,

Thanks to Mike's persistence and to your reports, our team seems to have tracked down the issue. The IT guys reported that there was a small change made to the way lulls were calculated on September 1st. However, it appears that it wasnít so small after all and they just rolled back the changes. Please keep an eye out and tell us if itís not working.

-Ben
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hein



Joined: 15 Aug 2000
Posts: 13

PostPosted: Mon Sep 05, 2016 1:01 pm    Post subject: Reply with quote

Thanks for tracking it down. But why would you be tweaking that mathematical relationship in the first place? That section of the code should be off limits.

If you allow the IT guys to make 'adjustments' then the reliability of your data just took a turn for the worse.
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windfind



Joined: 18 Mar 1997
Posts: 1372

PostPosted: Mon Sep 05, 2016 1:55 pm    Post subject: Reply with quote

The lull reading can be measured in many ways

It could be the deepest lull between each data point on the graphs.

Or it could be the average of the lulls over a sampling period between each data point.

Or it could be the lull at the moment the data is sent from our sensor to the server in FL.

Or it could be the standard deviation of the lulls from the average between data points.

All of these and many more are valid ways of representing the lull you see in the wind graph. The most accurate would be a standard deviation. But we have many generations of our sensors spread across the USA and each generation has different data handling capabilities so it is not easy to figure out the most useful way to depict data. Especially when some regions have very steady winds while others, like the Gorge, have huge variations between the average and lulls.

So IT tried to a different way of calculating the lulls and it clearly did not work for the west coast.

Mike
iwindsurf.com/ikitesurf.com
Weatheflow.com
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hein



Joined: 15 Aug 2000
Posts: 13

PostPosted: Mon Sep 05, 2016 2:33 pm    Post subject: Reply with quote

Thank you for the further clarification.
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dennis_c



Joined: 05 May 1998
Posts: 851
Location: Rio

PostPosted: Wed Sep 07, 2016 9:02 am    Post subject: Reply with quote

Can't imagine it worked for either coast, as a couple times we had a gust reading of 80 degrees at M14.
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