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Possible Beaufort Number Bug

From build 3044 the development baton passed to Mark Crossley. Mark has been responsible for all the Builds since. He has made the code available on GitHub. It is Mark's hope that others will join in this development, but at the very least he welcomes your ideas for future developments (see Cumulus MX Development suggestions).

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Mapantz
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Possible Beaufort Number Bug

Post by Mapantz »

During yesterday's storm Ciara, my wind speed got up to 31mph. <#Tbeaufort> returned F7 and <#Tbeaudesc> returned Near Gale which is absolutely fine.

Looking at my 'yesterday' page, <#Ybeaufort> is returning F6. But <#Ybeaudesc> is returning the correct 'Near Gale' description.
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Re: Possible Beaufort Number Bug

Post by mcrossley »

What is your <#windYM> tag showing?

31 mph should be F6 - Strong breeze.
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Re: Possible Beaufort Number Bug

Post by mcrossley »

But I see why 31 mph is producing different values for the number and description - it falls right into a rounding error issue in the description function. I'll fix that.
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Re: Possible Beaufort Number Bug

Post by Mapantz »

31.0

I was looking at my website when the wind got to that speed and <#Tbeaufort> definitely said F7 with the description of near gale. <#Ybeaudesc> is saying near gale. :lol:

Edit: Ahh I see. Phew! It wasn't me going lala then?!
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Re: Possible Beaufort Number Bug

Post by mcrossley »

OK, there are three functions that calculate the Beaufort force, one outputs the number as string, one as a number, one as a description.

The number/string, and description both have rounding errors, the numeric one is correct. I have fixed it so that there is only a single function to do the conversion, and the others just call that one!

The calculation is done in m/s, and 31mph = 13.858 m/s. The cutoff for F7 is < 13.9, so 13.858 was being rounded to 13.9 and incorrectly interpreted as F7
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Re: Possible Beaufort Number Bug

Post by richard_newberry »

Tell me if i am wrong that beautfort is related to average wind speed not the wind guest?

https://www.spc.noaa.gov/faq/tornado/beaufort.html
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Re: Possible Beaufort Number Bug

Post by mcrossley »

Correct, it should be average speed not gust. I'm not sure why Cumulus has peak gust values as well.

I use the peak average windspeed for Beaufort values on my website.
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Re: Possible Beaufort Number Bug

Post by richard_newberry »

Beautfort according to the met office is related to wind gust then wind average?
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Re: Possible Beaufort Number Bug

Post by mcrossley »

Scratch that - deleted post!

All the Beaufort values current, today, yesterday - use average speeds.
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Re: Possible Beaufort Number Bug

Post by Mapantz »

mcrossley wrote: Mon 10 Feb 2020 2:27 pm
The Today and Yesterday tags <#T/Ybeaufort>,<#T/Ybeaufortnumber>, <#T/Ybeaudesc> all use the peak gust speed which in my opinion is incorrect.

What to do about it though?
If I recorded a peak gust of 54mph yesterday, wouldn't have that shown up as F9?
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Re: Possible Beaufort Number Bug

Post by mcrossley »

Sorry Tina, I deleted my previous post - I was talking through my backside, couldn't read properly. They all use average values, so as you were.
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Re: Possible Beaufort Number Bug

Post by Mapantz »

:lol:

No problems!
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Re: Possible Beaufort Number Bug

Post by freddie »

mcrossley wrote: Mon 10 Feb 2020 1:10 pm31mph = 31.858 m/s. The cutoff for F7 is < 31.9, so 31.858 was being rounded to 31.9 and incorrectly interpreted as F7
31 mph is 13.858 m/s. Just saying, like 😀 But I guess you mean the F7 cutoff is 13.9...
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Re: Possible Beaufort Number Bug

Post by mcrossley »

Doh! Number blindness :oops:
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Re: Possible Beaufort Number Bug

Post by richard_newberry »

I have worked out the wind average and its not correct.
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