Wind direction graph weirdness

[Rob Cranfill]

Hi, all! Longtime user, and hoping this isn't too dumb a question.....

I have seen the ongoing discussions about the inherent difficulty of calculating "average wind direction" and am wondering if maybe that issue is what is causing the weirdness in this long-term graph, like this (taken from http://robcranfill.net/weather, which you are free to peruse!)

This is my yearly data, and I'm sure the wind does *not* actually blow like that. I had a friend/user ask me about why the graph looks like this, and I had no answer, except to say "No, there is nothing preventing my weather vane from pointing any way the wind blows!" :-)

Thanks for any info,

  rob in seattle

[vince]

That graph is kinda awful.  Belchertown has nicer ones.

(Federal Way about a mile from the water here)

Or you could use the StackedWindRose extension.

(The blue one attached.)

[Tom Keffer]

That is an odd graph of wind direction. I looked over a one-year plot of wind direction at my location, and it has a similar look. But then, I live in a gorge where the wind almost always blows east or west, occasionally from the south, almost never from the north.

Is there some way you could make your database available to me? Perhaps put it on a Google Drive, or FTP server? I'd like to take a closer look.

-tk

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[Jeff A. D.]

Looks like those are daily plots?  Should each plot correspond with the dominant direction (DOM DIR), the last column of the monthly NOAA report? 

[Tom Keffer]

Good point, Jeff

Looking at April 2023, the plot suggests wind direction is mostly SSE. The monthly summary the same.

Still, I'd like to see the database, if possible.

-tk

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[Rob Cranfill]

I’ll figure out how to do that and let ya know. Thanks! :-)

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[vince]

Rob - I'm in Federal Way a mile or so south of Redondo and my graphs 'do' line up with our prevailing winds here that tend to be from the SW in this location.  We rarely get wind from the NNE-SE directions.  It either comes off the Sound in the Port of Tacoma or from the SW from Browns Point.  Occasionally from the NW through a slot in the trees from the water next to Redondo but not too often.

Your graphs just look a bit bouncy to me which might be your siting.   See if your Vue vane is pointing into the direction weewx reports.   Mine down here is from the SW currently FWIW.

(if you watch local tv news, take a drink every time they say 'atmospheric river' this week)

[Tom Keffer]

Rob sent me a copy of his database, and I've had a chance to look at it.

Everything seems to be working properly. It's just that he has a lot of wind from the NE. Take a look at the date 3-Dec-2022, which is typical. Here's a histogram of wind direction. Note that this is just windDir, and it is not being weighted by windSpeed, which would require a 2-d histogram. Don't know how to do that in Excel.

The vast majority of directions are in the (0,15) range. WeeWX calculated the vector wind direction for this date as 28.9º, which seems about right.

-tk

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[Rob Cranfill]

Thanks for looking into this. I'm glad to hear it's not a bug! :-) I can imagine it's hard to portray the subtleties of a year's worth of data in one graph. Thanks for all your work!

</rob>

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[Tom Keffer]

One thing I would suggest: make sure the wind direction vane on your VantageVue is turning freely. It could be stuck in the NE position!

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[Rob Cranfill]

That's the thing - NONE of the daily or weekly graphs show this near-total lack of wind from the 180-360 direction. Here's a recent daily:

and a weekly:

monthly:

yearly:

It doesn't seem so odd if you look at each graph in turn, but if you just look at the yearly it seems quite odd. But again, I guess that's just cuz the graph is, necessarily, highly simplified.

</rob>

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[Tom Keffer]

I don't have an answer for that. It could be that the winds out of the SW quadrant are not very strong, so they don't contribute much to the daily average, but I'm theorizing. That's where a 2-d histogram would help.

I've looked through the algorithm twice, following the calculating in the debugger, and it all works the way it should. 

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[michael.k...@gmx.at]

The are 6 days in 2023 that are recognizable. Look at the daily/Weekly plots and how they look like. It should be possible to regenerate them, if you don't have any snapshots. For me, this looks like a classic upcast/valley wind graph.