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Thread: Strong wind gust frequency

  1. #1
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    Default Strong wind gust frequency

    I've been doing some research on strong gusts (150+ mph) from Mt. Washington, and I found some interesting results concerning their frequency from year-to-year.

    The NOAA had daily data back thru 1951; here are the frequency of days with at least one 150+ mph gusts:

    2007: 1
    2006: 1
    1996-2005: none
    1995: 1
    1994: 1
    1993: 1
    1992: none
    1991: 1
    1990: 1
    1989: 2
    1988: 1
    1986-1987: none
    1985: 2
    1983: 3
    1982: 1
    1981: none
    1980: 2
    1979: 2
    1978: none
    1977: 1
    1976: none
    1975: 1
    1974: none
    1973: 1
    1972: 1
    1971: none
    1970: 1
    1967-1969: none
    1966: 1
    1954-1965: none
    1953: 1
    1952-1951: none

    Check out the totals per decade:
    2000's: 2
    1990's: 5
    1980's: 11
    1970's: 7
    1960's: 1
    1950's: 1

    Does anyone have any ideas as to why there were so many strong gusts in the 1970s and 1980s, yet so few in the late 1990s/early 2000s, and 1950s-1960s?

    I'd also like to make a list of all dates with average wind speeds of 100+ mph, but they don't list 'highest average wind speed for a single day' on the annual reports, so it would take MUCH longer to put that list together because I'd have to check every single month's report.

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    To throw a wrench into your works, remember that the Observatory moved to the northeast side of the summit in 1980. Since the exact location of the anemometer will register geographic micro-effects (my terminology), the 70s and 80s are apple and oranges.

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    This reminds me of an old Simpsons episode ("Hurricane Neddy" EP #161)

    Homer: Oh Lisa, there's no record of a hurricane ever hitting Springfield.

    Lisa: Yes, but the records only go back to 1978 when the Hall of Records was mysteriously blown away!

    Quote Originally Posted by Mike D
    To throw a wrench into your works, remember that the Observatory moved to the northeast side of the summit in 1980. Since the exact location of the anemometer will register geographic micro-effects (my terminology), the 70s and 80s are apple and oranges.

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    Quote Originally Posted by spyboy
    This reminds me of an old Simpsons episode ("Hurricane Neddy" EP #161)

    Homer: Oh Lisa, there's no record of a hurricane ever hitting Springfield.

    Lisa: Yes, but the records only go back to 1978 when the Hall of Records was mysteriously blown away!
    I'm glad I'm not the only one who has a majority of their sentences begin 'this reminds me of a simpsons episode...'

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    The 100mph days would be an interesting stat.

    Here's a question. In a cloud free environment, over the plains, do you think there are wind gusts at 30,000 ft?
    Bill
    Next up: Vermont City Marathon: May, 2011
    EasternLight

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    Gah, I hate to raise this, but define "gust". We have had numerous conversations during meetings about what a gust is. It seems simple enough, but like anything else, the devil's in the details. The official definition is at least a 10 knot deviation from lull to peak during the 10 minutes preceeding the time of observation. It's very arbitrary.

    In any case, the answer is "no" because wind is defined as the horizontal motion of air over the Earth's surface.

    Quote Originally Posted by Bill O
    The 100mph days would be an interesting stat.

    Here's a question. In a cloud free environment, over the plains, do you think there are wind gusts at 30,000 ft?

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    This list is by no means comprehensive, since I found these just by checking the months with some high gusts, but here's a list of the dates I found that had a 100+ mph average wind speed for 24 hours, with the day's highest gust in parantheses:

    116.8: 12/04/1980 (178)
    102.5: 01/09/1985 (150). The avg is estimated to be between 102 and 103; it's blocked out on the report but can be calculated using the monthly average wind speed.
    102.0: 04/05/1995 (157)
    101.9: 01/16/2006 (142)
    101.4: 04/03/1970 (151)

    The days that seem to take the cake are of course April 11-12, 1934. From 4pm on 4/11/1934 to 4pm on 4/12/1934, the total wind movement was 3095 miles, for a 24-hour average of 129.0 mph, with the peak gust being 231mph.

    It's likely that there are several other 100mph days out there, but it's extremely time-consuming using NCDC's website to look at this info.

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    Here's some data from when I was on the summit:

    http://www.easternlight.net/journals/kmwn0020.htm

    Fastest day was just under 80mph, and that was a windy day. I can't imagine how fun a 100+ day is.
    Bill
    Next up: Vermont City Marathon: May, 2011
    EasternLight

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    I wonder if any areas experiencing tropical storms had 2400 miles of wind in a 24-hour period. Maybe if it were a slow-moving storm or they had a long period of very high speeds, it might make up for the slow periods when the storm wouldn't be as strong...

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    I got most of the info about the 1934 record winds from the June issue of Monthly Weather Review. One sentence caught my eye:

    "The new heated anemometer, securely installed 10 feet above the roof ridge, has proved to be entirely satisfactory..."

    They include a photograph of the observatory, which clearly shows the anemometer situated on top of a shack.

    Recall that Grandfather Mtn in NC had their anemometer on top of the roof of a building, and that's why their record gust was discounted, as winds accelerate as they go over the roof of the building.

    I'm not certain of the exact configuration at Grandfather when they recorded a 200mph wind.

    The question is: our interest in MWO aside, should we discount the 231mph gust because it could likely have been influenced by the same configuration that invalidated Grandfather Mtn's gust?

    Here's the link to the first part of the article: MWO Record Wind gust article from June 1934 MWR .

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