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Thread: Big Wind Contest ...next 48 hours

  1. #61
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    Default

    Thanks for the clarification. Makes us accuracy snobs feel much better.
    Bill
    Next up: Vermont City Marathon: May, 2011
    EasternLight

  2. #62
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    Quote Originally Posted by JimS
    ...I'm only calabrated to compute data the uncorrected way...
    Perhaps you should calibrate yourself to spell correctly. Darn science teachers.

    Brian Clark

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  3. #63
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    Quote Originally Posted by Bill O
    Thanks for the clarification. Makes us accuracy snobs feel much better.
    No problem Bill....glad that made sense.
    Brian Clark

    MWO Observer and Meteorologist

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  4. #64
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    Quote Originally Posted by bclark
    Perhaps you should calibrate yourself to spell correctly. Darn science teachers.

    Me fail english, tha'ts unpossible!
    "I've learned that everyone wants to live on top of the mountain, but that all the happiness and growth occurs while you're climbing it."
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  5. #65
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    Default Use The Setra!!!

    Quote Originally Posted by bclark
    As Neil pointed out, wind speeds/gusts measured by the Setra pressure transducer are not corrected for temperature and pressure. Therefore, the 148.5 mph gust is not entirely accurate considering the actual temperature and pressure outside at the time the wind gust was measured.

    I was unable to use the Setra to calculate the corrected wind gust because we only save the high resolution differential pressure data used by our computer database to calculate that gust for 20 minutes. So, the Barton high speed wind chart had to be used to calculate it.

    So after running through the proper calculations, the official corrected wind gust is.....(drum roll please).....

    136.5 mph

    That also means that my buddy Mr. Jim is not the winner of this contest. It is actually WSR88D with a guess of 138 mph. And no Jim, you can't argue that your guess was for the uncorrected wind gust. You should have known from that start that 148.5 was uncorrected Perhaps in the future it will be best to specify that guesses are for CORRECTED gusts.

    Look for a more detailed writeup about this in the observer comments at some point later today.
    Equations by definition work both ways. You should be able to use the measured wind speed from the Setra, resolve the equations back to to a differential pressure in inches of water, and then recalculate for temp/pressure errors. The setra actually works more or less identically to everything else, an inch of water is an inch of water, regardless of the device. Thus the same equation that you use for the Barton applies to the setra.

    I'll try to take a look at it this evening if I get a chance.

    Use the setra. It is far more sensitive than the Barton. Also was the needle on the Barton changed prior to the storm? if not it was probably dried up, and had a lot of frictional drag, hence the lower speed. As a note: the setra and barton agreed extremely well for the 158 mph event back in October of 06.

    Lastly, the corrections are typically only applied for record setting gusts... not just any big wind.

    -Neil

  6. #66
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    Quote Originally Posted by bclark
    Perhaps you should calibrate yourself to spell correctly. Darn science teachers.

    If you can only spell things one way you are lacking in creativity.
    Brad (a 6288 club member)
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  7. #67
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    Default Corrected wind gust...for real this time...

    Quote Originally Posted by Neil
    Use the setra. It is far more sensitive than the Barton.
    Ok, so I have learned a lot over the last couple days in dealing with correcting this wind gust for temperature and pressure. Neil is right, the Setra is a much better device to use to determine the corrected wind speed. I used the equation we use to turn the differential pressure measurement from the Setra into a wind speed, and solved for the differential pressure created during the 148.5 wind gust that the Setra measured assuming a standard temperature and pressure. This gave a measurement of 9.13 inches of displaced water column.

    Then, I recalculated the corrected wind speed using this differential pressure instead of the one from the Barton chart. This gave me a corrected wind gust of 144.6 mph. This is only a 2.6% correction from the 148.5 gust originally measured

    This is going to be the final and official corrected wind gust for this event...and I'm serious this time.

    So, that changes the winner of the contest yet again. Sorry WSR88D, it is actually KD who is the winner with a guess of 144.
    Brian Clark

    MWO Observer and Meteorologist

    http://mountwashington.accuweather.com<---- My blog on AccuWeather.com

    We are....PENN STATE!!

  8. #68
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    Default ummm....

    Yah, eye noo dat! Me go sweep floor and empty trash now. Yoo beeg 4-head guys need NE mor cal-q-lay-shuns, u lemme no.

    KDT

  9. #69
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    Quote Originally Posted by KD Talbot
    Yah, eye noo dat! Me go sweep floor and empty trash now. Yoo beeg 4-head guys need NE mor cal-q-lay-shuns, u lemme no.

    KDT
    Can I have your order graph?
    Brad (a 6288 club member)
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