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Thread: Forecasting

  1. #1

    Forecasting

    How is it done?
    For example, Florence is in the middle of the Atlantic right now. How would one forecast when and if any waves will arrive in the north east? How big might they be? How fast do waves travel in the open ocean? Florence is moving west at 15 mph and has winds of 35mph what can we predict from this info.
    How much fetch is needed? How much do waves dissipate along the way?
    Really I’m looking for general knowledge on the topic… TSs and Hurricanes makes waves, what are other systems too look out for?
    Do you use any tricks or rules of thumb to estimate this kind of stuff? If a storm is in the middle of the Atlantic it takes roughly 5 days to send waves.. stuff like that.

    Thanks for sharing your knowledge.
    Best,
    M

  2. #2
    Join Date
    Sep 2010
    Location
    Long Buried Island
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    685
    Im am no expert but I predict these storms by looking at each storm as a ball of energy. Florence has very little energy and will not send us much if any swell. Our swell window is realitively small so we need the northwest side of storm to be strong to send us decent swell. I have a feeling that this tropical season will be very weak, I am only expecting a couple of swell making tropical storms this year but the Noreaster season could be really good this year.

  3. #3
    Join Date
    May 2006
    Location
    Lewes, DE
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    To get you started on the basics of wave forecasting, there are 3 main factors that influence swell size.

    Wind Speed
    Wind Duration
    Wind Fetch

    As each one of these 3 variables increase, so do wave heights.

    If you compare a small tropical storm of 50mph to that of a strong frontal low pressure system of 50mph, the big difference is the wind fetch. A frontal system fetch can range as large as 500-1000 miles, while tropical storms are much smaller.

    For tropical storm systems, you will want to look at the size of the storm, the direction it is going, and the wind fetch that is pointed in your direction. Max wind speed alone can be deceptive, because that is usually only a small area of the storm with the strongest winds.

    Or you could let the wave models handle the work. The wave model physics is very good, but are only as good as the wind input. And, when it comes to small scale systems, like hurricanes, wind intensity is the hardest factor to pinpoint.

  4. #4
    Quote Originally Posted by MNT View Post
    How is it done?
    For example, Florence is in the middle of the Atlantic right now. How would one forecast when and if any waves will arrive in the north east? How big might they be? How fast do waves travel in the open ocean? Florence is moving west at 15 mph and has winds of 35mph what can we predict from this info.
    How much fetch is needed? How much do waves dissipate along the way?
    Really I’m looking for general knowledge on the topic… TSs and Hurricanes makes waves, what are other systems too look out for?
    Do you use any tricks or rules of thumb to estimate this kind of stuff? If a storm is in the middle of the Atlantic it takes roughly 5 days to send waves.. stuff like that.

    Thanks for sharing your knowledge.
    Best,
    M

    google it
    if you don't want to google it, surfline actually has some good stuff about surf forecasting. But what it all boils down to is how hard the old man in the sea is turning the crank shaft on the wave machine.

  5. #5
    Thanks for the info!