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  1. #1

    Tropical Storm groundswell duration

    I'm wondering how long groundswell from a tropical storm usually lasts. Let's say Bertha continues on its project path, maintains its status as a tropical storm, then starts heading away (towards the north and east) once it's a few hundred miles southeast of Bermuda.

    Given these conditions, how long could we expect groundswell to last? I know there are many variables, but just looking for a rough timeframe (1 day, 2-3 days, 4-5 days, more?). Don't the longer period waves travel faster than the shorter period? Does this mean we'll get larger waves first and smaller later or does this only speak to the time between waves? Thanks in advance for any information...

  2. #2
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    Quote Originally Posted by matthwh610 View Post
    Don't the longer period waves travel faster than the shorter period? Does this mean we'll get larger waves first and smaller later or does this only speak to the time between waves? Thanks in advance for any information...
    You are correct in that the longer period waves do travel faster and we'll see them first (since they move quicker they reach the destination sooner). The speed of waves is correlated to the period. Longer period = faster waves. I don't know about the time frame of days you were speaking of though, gotta hope someone else posts haha.

  3. #3
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    This is so far out right now I wouldn't be getting to excited just yet!! Just cross your fingers and hope, but don't count on it.

  4. #4
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    I hope that Micah jumps in soon - latest NWS discussion on Bertha states that she should be a hurricane in 72 to 96 hours!!!! She's going to be hitting some cooler waters, but wind shear doesn't appear to be an issue right now.

    I'm wondering if she's going to be one of those ferocious little Cape Verde numbers...

    Yeesh.

  5. #5
    Should become subtropical as well.

  6. #6
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    one of the most important aspects for the tropical storms is the direction it is moving. The storm is very far away from us... however if it produces winds in our swell window and is moving towards us, then it can produce waves our way.

    At this point, it is just barely at tropical storm status, but it does have a good path on it. For us to get any substantial swell, we need the wind speeds to increase a bit. The winds are forecasted to increase over the next few days, however the NHC still has this storm under hurricane status.

    At this point, I wouldnt expect anything big from this storm, but at this point, I'm thinking we could see a few days of fun 2-3-4' stuff. The main negative factor right now is the storm is moving towards colder waters.

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    Quote Originally Posted by pvjumper05 View Post
    You are correct in that the longer period waves do travel faster and we'll see them first (since they move quicker they reach the destination sooner). The speed of waves is correlated to the period. Longer period = faster waves. I don't know about the time frame of days you were speaking of though, gotta hope someone else posts haha.
    If you want to simplifiy things the velocity of the wave form in translation is just a simple non-linear equation of:

    In shallow water, where we would surf, v = sqrt(gd), where g=32.2 ft/sec^2 and d is the depth of the ocean at that point.

    In the open ocean, v=sqrt (gP/2pi), where P=period...and because P is in the numerator the speed increases therefore faster swells.

    How long it takes is basically distance/velocity, so determine where you want to determine the time from and divide by the velocity from above.

    One thing that is also working our favor is the track as Micah had eluded to because IF Big Berfa maintains the same track for a certain time duration, a phenonmenon known as virtual fetch develops and just like normal fetch, it will send waves propagating in the mean direction.


    Hope this helps with your forecasting

    Birdman.
    ________
    headshops
    Last edited by SkySurfnSnow; Jan 24, 2011 at 10:55 AM.

  8. #8
    Quote Originally Posted by SkySurfnSnow View Post
    If you want to simplifiy things the velocity of the wave form in translation is just a simple non-linear equation of:

    In shallow water, where we would surf, v = sqrt(gd), where g=32.2 ft/sec^2 and d is the depth of the ocean at that point.

    In the open ocean, v=sqrt (gP/2pi), where P=period...and because P is in the numerator the speed increases therefore faster swells.

    How long it takes is basically distance/velocity, so determine where you want to determine the time from and divide by the velocity from above.

    One thing that is also working our favor is the track as Micah had eluded to because IF Big Berfa maintains the same track for a certain time duration, a phenonmenon known as virtual fetch develops and just like normal fetch, it will send waves propagating in the mean direction.


    Hope this helps with your forecasting

    Birdman.
    BIRDMAN...WHAT THE HECK ARE YOU TALKIN' ABOUT?????

  9. #9
    A thing to keep an eye on with this storm is it's recurvature. This will be dictated by the strength of the storm. A stronger storm is going to recurve earlier. A weaker storm would have a chance to make it as far as Bermuda in it's recurvature.

    Overall the system has an extremely low chance of giving us anything spectacular in the form of swell. Maybe an elevated day or two at best but it might not even do that.

    Check back in five days to see where it's at before really watching it in terms of your own plans.

  10. #10
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    I would take one or two days of groundswell. Those days of little Southern Hemi swell were pretty sweet.......although small. Groundswell makes such a difference, I'll take whatever I can get....