Average Wind Speed confusion

[RayProudfoot]

My station in Cheadle Hulme is about 4 miles north of Mark Crossley's in Wilmslow. We're both running build 1011.

Today's Average Wind Speed for Mark's station is 30.8mph at 09:08. Mine is 17mph at 09:13. Mark's Wind Run is 183 miles, mine is 189.4 miles.

How can two stations so close together with such similar wind data have such a large discrepancy in Average Wind Speed? I have a VP2 and Mark has a Fine Offset WH1090. Is that a factor or is it a setting in Cumulus?

[steve]

That just demonstrates how you can never compare your data with anyone else's unless you have exactly the same equipment, both sited in ideal conditions. Fine Offset stations present their wind data in a completely different way to Davis stations. Looking at your wind graph and Mark's, it looks like it got particularly gusty at about that time, and I'm guessing that Mark is using the station's gust figure to calculate the average speed. It's possible that this exaggerated the average speed while it was gusty; but the fact that your wind run is comparable suggests that overall that method works well.

[6719jason]

I was wondering about my average wind speed also.

How is it calculated for La-Crosse Weather Stations?

I know these stations only supply a Gust Wind Speed.

[steve]

I was wondering about my average wind speed also.

How is it calculated for La-Crosse Weather Stations?

With the default settings, it's the wind speed supplied by your station.

[RayProudfoot]

That just demonstrates how you can never compare your data with anyone else's unless you have exactly the same equipment, both sited in ideal conditions. Fine Offset stations present their wind data in a completely different way to Davis stations. Looking at your wind graph and Mark's, it looks like it got particularly gusty at about that time, and I'm guessing that Mark is using the station's gust figure to calculate the average speed. It's possible that this exaggerated the average speed while it was gusty; but the fact that your wind run is comparable suggests that overall that method works well.

Thanks for the explanation Steve. I looked at my data on WUnderground for the 10 minute period ending at 09:13. The 5 minutes ending at 09:07 had a wind speed of 18mph and 16mph at 09:12. That would make the average 17mph over 10 minutes so that would confirm its accuracy.

Mark's readings were 26.4mph at 09:04 and 30.4mph at 09:09 suggesting the average should be 28.4 but it's 30.8mph. Clearly there's more to this than meets the eye.

[mcrossley]

Ray, the WOW site shows a good comparison of today's wind on both our stations I think.

Don't forget my wind speed sensor is much lower than yours and tree shaded (though not as badly for N/S wind directions as E/W) so I also apply a correction factor to it to 'lift' the readings somewhat. It is a project on the books to get the sensor roof mounted.

[steve]

Mark's readings were 26.4mph at 09:04 and 30.4mph at 09:09 suggesting the average should be 28.4 but it's 30.8mph.

You can't calculate his average wind speed at 0908 by averaging his average wind speeds at 0904 and 0909. There's no reason why his average couldn't have been higher than either of those two figures at 0908.

[RayProudfoot]

Ray, the WOW site shows a good comparison of today's wind on both our stations I think.

Indeed it does, thanks Mark.

Don't forget my wind speed sensor is much lower than yours and tree shaded (though not as badly for N/S wind directions as E/W) so I also apply a correction factor to it to 'lift' the readings somewhat. It is a project on the books to get the sensor roof mounted.

I've noticed that my high gust is nearly always higher than yours but oddly you had the higher one today despite the ane being mounted lower. The correction factor plus the different manufacturer clearly has a major effect.

[RayProudfoot]

Mark's readings were 26.4mph at 09:04 and 30.4mph at 09:09 suggesting the average should be 28.4 but it's 30.8mph.

You can't calculate his average wind speed at 0908 by averaging his average wind speeds at 0904 and 0909. There's no reason why his average couldn't have been higher than either of those two figures at 0908.

Fair point. Once you start averaging averages you're into Government statistics territory and we all know what that leads to!!

[6719jason]

With the default settings, it's the wind speed supplied by your station.

Thanks Steve for the explanation

[RayProudfoot]

Interesting comparison between a squall this afternoon and yesterday's ex-hurricane.

My highest 10-min average wind speed yesterday was 17mph but that was beaten today with 18mph at 16:01 as a short but quite pronounced squall passed through this area. Highest gust was also 36mph. Temperature fell 8 degrees F in 16 minutes too. Interesting!