Topic: Wind Gust Question

[PSL]

Yesterday morning (3-7-17) about 11:00 AM, I turned off WU sharing on the Acurite dashboard and began using Kevin Key's bridge software. It's working great, reporting to WU with no gaps in temp / humidity. However, I noticed that on the wind graph, gusts are reported each time the wind is updated.

I thought that gusts would not be reported unless the wind was 18 mph or greater as one of the criteria. Clearly, from the graph below, I'm reporting very low gusts.

Is anyone else who is using Kevin's software, seeing this?

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[Jáchym]

In 99% cases stations/SW do not report real gust, what they do is they send wind speed as average over some period (depends on the update interval) and as gust they send the max from that interval

[PSL]

Jachym,

Thanks for responding. I think I understand it. Acurites software did not report gusts to WU unless it met the criteria. Kevin's reader apparently sends this info to WU as an average over the time interval.

[DoctorKnow]

18 MPH+ or a sudden gust of wind greater than or equal to that is what the NWS says is a gust. Like was stated by Jachym, most software relaxes that since a lot of anemometers do not take a rapid enough reading to tell. Ultimeter weather stations are one of the few consumer level stations that I know of that take 1 second readings.

You can adjust the wind speed by changing the percentage from 100. I recommend adding 30 to 40% if your station is at 30 ft, even more if it is closer to the ground. I have taken comparisons, and the wind speed is around 3 MPH low on the 5 in 1. So you would put in 140 where it says "wind offset"

[Jáchym]

I agree that the wind speed is biased if measured close to the ground, but making such general adjustment is IMHO not a good strategy either. It really depends and this could be creating even more inaccuracies in your data, especially when the speed is higher. It could work for you, but this is influenced by local conditions so much that you cant make such generalizations, depends on surroundings, elevation, wind patterns, direction, temperature, etc etc

I personally would rather say - this is the wind speed measured at XY height, but it is accurate for this height rather than "this is an estimate for 10m height" - because that means you lost the original accurate information and now you have one estimate and dont know the accurate original either

[DoctorKnow]

Good point, but these cheap 18 second stations are not fast enough to catch all the wind, so that is why I add a little offset to help, and I have come very close to the official sites doing so.

[Jáchym]

And thats a problem too...

very close to the official sites

wind speed is something you cannot compare to close stations, when we do interpolations at our institute, it works great for pressure, more or less ok for temperature (if the stations are reasonably close and at same elevation), more problematic with precipitation (have to be really close) and unusable for wind speed.

Move the sensor 100m away and you will measure something different, you have local turbulences, wind patterns etc etc. We have professional stations some of which are very close and the wind is totally different. Unless you are in an absolutely opened space as well as the other station and nothing really is between you and the other station (trees, buildings etc.).

So maybe you just happen to live in such a location that you can match the nearby official one, but.... We have a network of over 600 stations so I know this really cannot be generalized

[jrswiss]

+1 @Jáchym
Agree to 100%.

We measure the wind 10 meters over ground with 2 Davis Vantage Vue Weather stations. The next house, tree, etc.. is over 350 meters away. Weather stations installed 10 meteres away from each other. On 'calmy days' (around 5mph) we got complete different speeds.

Also please read Wind Gusts measurement from WU here: http://wiki.wunderground.com/index.php/Educational_-_Wind_gusts_vs._gust_speed

[PSL]

Thanks to all for the responses. My station is about 15 feet off the ground. I tried changing the wind offset in Kevin's software to 140, 125, 120 and to me, it appeared that my recorded wind speeds were generally higher that some surrounding station reports on WU. I understand what you were saying about the variances from one station to another even a few feet apart.

So, I went back and changed the wind offset back to 100% for now. I guess I can live with the rather low "gusts",<18mph, showing on my WU graphs.

Thanks again for your help.

[DoctorKnow]

PSL,
Thanks for the report. That means that my station may have a problem with the cups dragging, probably from the bearings being shot. I am not going to throw another dime at this one though. I'll wait for the atlas line, before I do anything.

Also though, keep in mind that the stations you are comparing to, may well be poorly sited, or not working properly. I would check on the nearest NWS, site or airport etc to see what they show, or compare against another brand at home. I had an Oregon Scientific to compare to the acurite, and it was reading higher, especially in winds over 10 MPH.

[Jáchym]

The normal wind sensors are very inaccurate, like it or not, it is true, they need relatively often calibration, they get covered with dust, the dust gets into the mechanics of it etc etc. Because of this we started purchasing ultrasonic sensors, which are much more expensive, but we thought it would help.

After about 2 yrs we compared the data from these professional stations equipped with US sensors (and keep in mind that in this case we are talking about stations worth 10+k USD), and we were very disappointed. Even though nothing is turning there, there are still parts and some rubber gaskets, which over time either get covered in dust or when subjected to freezing temperatures and then quick temperature increase, they tend to lose flexibility and affect the measurements too....

Wind is by far the most problematic parameter of all. Very difficult to measure, extremely variable both spatially and in time (i.e. practically no possibility to interpolate or compare)

[PSL]

DoctorKnow, thanks again. My 5in1 station is about 2 years old. I've had little trouble with it except for Acurite's latest problems with the Smarthub issues reporting temp gaps to WU. I eliminated the gap problem until they come up with a fix by using Kevin's software.

As far as the new Atlas line, it looks promising, but I'll wait to see how they actually perform before switching.

Right now, i'm somewhat in line with surrounding stations and I do try and compare my readings to a local airport, just a couple of miles away. Most of the time, I'm in pretty good agreement with their readings except for wind speed. They're usually higher, but their location is higher and unobstructed. Basically, my readings are fine for my non-critical purposes.

[DoctorKnow]

 Jáchym,

When the tree branches (bare) are visibly moving slightly, wouldn't you say that wind speed is around 10 MPH?

[Jáchym]

Estimating wind speed from branch movement.... IMHO not very accurate

[Scalphunter]

Water cues for wind speeds are lot better then using tree branches. Beaufort  wind scale.

[okieman98]

Yesterday morning (3-7-17) about 11:00 AM, I turned off WU sharing on the Acurite dashboard and began using Kevin Key's bridge software. It's working great, reporting to WU with no gaps in temp / humidity. However, I noticed that on the wind graph, gusts are reported each time the wind is updated.

I thought that gusts would not be reported unless the wind was 18 mph or greater as one of the criteria. Clearly, from the graph below, I'm reporting very low gusts.

Is anyone else who is using Kevin's software, seeing this?

 [ You are not allowed to view attachments ]

are u useing a new hub are a older one, i have been trying to get it to work for me

[PSL]

oakieman,

I'm using an older hub that I bought in April, 2015. It was migrated to the new Acurite, amazingly with no glitches at the time.

[okieman98]

ok thanks