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Thread: Southern Mountain giving Mt Washington a run in wind speed

  1. #11
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    Quote Originally Posted by treant985
    I agree that several 190+ readings in a year is pretty unlikely. However, isn't it true that MWO has never observed another 180+ since that day with 231? I'm just going on memory from an old weather book by Ludlum, so I'm not sure. Was the 231 gust measured with a pitot?
    I think that is true, unless it was in April, because nothing outside April is over 180mph.

    The 231 was recorded with a modified 3-cup, not a pitot. Well, it worked on the same principal as a 3-cup.
    Bill
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    Quote Originally Posted by Bill O
    I think that is true, unless it was in April, because nothing outside April is over 180mph.

    The 231 was recorded with a modified 3-cup, not a pitot. Well, it worked on the same principal as a 3-cup.
    Do you know off-hand of any articles or studies that were done about the 231mph gust? I found some stuff in the June 1934 Monthly Weather Review, but I'm hoping for something a little more recent.

    I'm sure a bunch of people questioned such a high reading during a minor storm, so it seems like there'd be several articles done where the author tried to verify/refute the reading.

    The Grandfather Mtn anemometer only being able to go to 224mph reminds me of a similar circumstance in Alaska. Everyone there claims they'll never be able to officially break the North American low temp record (-81.4 in Snag, Canada) because the NWS minimum thermometers only go to -80. Of course, they could mark the glass if the mercury drops lower, but it'd be an ordeal to get the thermometer tested later, for accuracy.

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    I don't know any, but I'm sure they are out there.

    I did stumble onto this information on MWO's site:

    Wind Record

    It's good to know that there is a National Extremes Committee, and that they agree that Mount Washington's 231mph is the record. I have a feeling there is a World Extremes Committee as well, and they also agree.
    Bill
    Next up: Vermont City Marathon: May, 2011
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    Quote Originally Posted by treant985
    The Grandfather Mtn anemometer only being able to go to 224mph reminds me of a similar circumstance in Alaska. Everyone there claims they'll never be able to officially break the North American low temp record (-81.4 in Snag, Canada) because the NWS minimum thermometers only go to -80. Of course, they could mark the glass if the mercury drops lower, but it'd be an ordeal to get the thermometer tested later, for accuracy.
    It doesn't detract from your point, but as I understand it, mercury is never used in thermometers for readings that low. Alcohol is typically found in low thermometers, but I wonder if the ones in question are digital, not using any liquid at all.

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    Quote Originally Posted by Mike D
    It doesn't detract from your point, but as I understand it, mercury is never used in thermometers for readings that low. Alcohol is typically found in low thermometers, but I wonder if the ones in question are digital, not using any liquid at all.
    Thanks for correcting my post. I'm usually the one who tells people that they use alcohol in the minimum thermometers, instead of mercury. I think that, as long as it's deemed an accurate device, observers can use whatever kind of thermometer they want.

    I've read that the observer in Embarrass, MN, used a digital one until it broke at -64F on the coldest day anyone had recorded in MN. It cost him the state all-time low record (to nearby Tower, which got to -60), even though he had labs verify the -64 reading. He switched to alcohol minimum thermometers after that.

    It's been a while since there were temps in AK down to -75 or lower (Jan 1989 I believe), so I bet that all those were done with alcohol thermometers, but it would be interesting to see how many places use digital ones now.

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    Quote Originally Posted by Bill O
    I don't know any, but I'm sure they are out there.

    I did stumble onto this information on MWO's site:

    Wind Record

    It's good to know that there is a National Extremes Committee, and that they agree that Mount Washington's 231mph is the record. I have a feeling there is a World Extremes Committee as well, and they also agree.
    Here's a little background info that I came across:

    I read a report by the Army Corps of Engineers from 1985 that mentions global weather extremes. They say that "in such strong winds, no apparatus can record the airflow except approximately, and actual velocity (of the 231 gust) may be in error by 10 to 40 miles per hour."

    However, "a value of 225 MPH, after anemometer calibration, is given in some sources." I guess, after a while, they figured the 231 was close enough to not warrant any corrections.

    Interestingly, the Army report says that the 231mph gust had the same force as a 180mph gust at sea level, which may put the 207mph gust at Thule, Greenland (elev. 990ft), as #1 in terms of actual force.

    By the way, this Thursday is supposed to be windy up in the NC mountains, so it'll be interesting to see if the new anemometer at Grandfather Mtn is reporting data publically by then. I emailed them to ask if the data currently online is from the new one or the old anemometer, but I've yet to hear back.

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    Quote Originally Posted by treant985
    Here's a little background info that I came across:

    I read a report by the Army Corps of Engineers from 1985 that mentions global weather extremes. They say that "in such strong winds, no apparatus can record the airflow except approximately, and actual velocity (of the 231 gust) may be in error by 10 to 40 miles per hour."

    However, "a value of 225 MPH, after anemometer calibration, is given in some sources." I guess, after a while, they figured the 231 was close enough to not warrant any corrections.

    Interestingly, the Army report says that the 231mph gust had the same force as a 180mph gust at sea level, which may put the 207mph gust at Thule, Greenland (elev. 990ft), as #1 in terms of actual force.

    By the way, this Thursday is supposed to be windy up in the NC mountains, so it'll be interesting to see if the new anemometer at Grandfather Mtn is reporting data publically by then. I emailed them to ask if the data currently online is from the new one or the old anemometer, but I've yet to hear back.
    Well, that report is flat out wrong. A 231mph gust at 6,288ft would feel stronger at sea-level...no matter how you cut it. The air is denser at sea-level, so at the same speed it exerts more force.

    I'd also hold a serious argument to an error of 10-40mph. Maybe in 1934, maybe with a 3-cup at 200mph, but not with a pitot tube. The claim that no device can measure such high winds accurately is crazy. Did they not have sonic anemometers back then? What about wind tunnels? The produce wind over 150mph in those, and I bet they measure it accurately within 1-2%.

    How about the space shuttle? I'm guessing their pitot tube used for landing measures airspeed using decimal places.
    Bill
    Next up: Vermont City Marathon: May, 2011
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    Quote Originally Posted by Bill O
    Well, that report is flat out wrong. A 231mph gust at 6,288ft would feel stronger at sea-level...no matter how you cut it. The air is denser at sea-level, so at the same speed it exerts more force.

    I'd also hold a serious argument to an error of 10-40mph. Maybe in 1934, maybe with a 3-cup at 200mph, but not with a pitot tube. The claim that no device can measure such high winds accurately is crazy. Did they not have sonic anemometers back then? What about wind tunnels? The produce wind over 150mph in those, and I bet they measure it accurately within 1-2%.

    How about the space shuttle? I'm guessing their pitot tube used for landing measures airspeed using decimal places.
    Yea, since the report is over 20 years old, it doesn't factor in any newer wind-sensing instruments. Just think of how much technology in general has advanced in the past 20 years. I think part of the 'discrepancy' between measuring wind speeds has to do with the fact that devices in wind tunnels are probably much better at measuring a constant stream of air, compared with anemometers that have to adjust quickly to rapidly-changing gusts. If the wind kept up at 231mph for maybe half a minute (in the 1930s) or a full second or two (nowadays) then it would obviously be a lot more reliable reading compared to just a quick burst that registered 231mph.

    I think you've got the right idea about the wind force but may have just incorrectly read my post. I meant that the 231mph gust at 6288 feet is equivalent in force to a 180mph gust at sea level, so you're right that 231mph at sea level would feel much stronger than it would at MWO.

    The 10-40 mph 'error' was only in reference to the device used to measure 231mph in the 1930s, not the standard error one can expect in any attempted measurement of winds that strong.

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    I just read another forecast for the NC mountains that say that the winds this Thursday and Friday could be the strongest yet this winter. I guess that doesn't necessarily mean the strongest gusts, but I'll keep an eye on the Grandfather Mtn (and Mt. Mitchell, too) online live weather stations to see if any register a triple-digit gust.

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    Sorry, I did read that wrong. 231mph at 6,288 would feel like 180mph at sea level. Sorry about that. But if you are looking at how fast the air particles are moving over the summit, 231mph is always 231mph.

    The beauty of the pitot is that it continuously measures the wind. It doesn't sample once every 5 seconds or .1 seconds, it is continuous. Save for some compression of the air in the tube.

    Now, the 1934 device and many other types of anemometers have momentum. They can't physically capture a one second gust. The tend to dampen out the gusts.
    Bill
    Next up: Vermont City Marathon: May, 2011
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