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  1. #1
    Join Date
    Jul 2007
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    Easton Md
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    Micah, question on tide heights, etc...

    Micah is there a reason why on the west coast tide heights are given ie:4.3 while they are not given on the east coast...whenever you see a westcoast surf report the heights are given while on the east coast they arent...am i wrong?

    or shall i say maybe given, but more talked about on the west coast...

    and another question why on the west coast do they always emphasize swell direction in degrees while that is not talked about here on the east coast?

    thanks
    Last edited by Beef; Oct 18, 2007 at 04:42 AM.

  2. #2
    Join Date
    May 2006
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    good questions...

    First off the tides:
    Yes, the actual height of the high and low tides is a big factor... and does influence the east coast surf as well. However, these changes in tidal heights dont seem to be as influencial on the east coast. The major difference here is that the west coast is dealing with generally much long period swells. The longer the period swell, the more influence the water depths will influence the refraction/defraction and shoaling processes.

    As for the emphasis on swell direction:
    In Southern California, especially this is important, because of the wave shadowing due to point conception (to the north) and the offshore islands. So, a couple degree change can make or break a particular area as the swell will either be blocked or pass through the southern california bight region. This setup, makes SoCal one of the most challenging areas in the world to forecast for.

    Having said that, the precise degree of the swell is important everwhere, but particularly when you are talking about steep angled swells ! So, in Delaware, many beaches face pretty much due East. So, as a generalized statement, lets say Delaware receives anything from due N to due S swells. But, if there is a little bit of W during a wind swell event, then it makes a big difference. So, a swell from 180 degrees will be bigger than the same size swell from 185 degrees and so on. Swell refraction is a big factor with these type of steep angled swells, and is one of the hardest things to forecast. The refraction process varies from break to break, and understanding this generally requires intimate knowledge of particular spots.

    The Swellinfo detail forecasts, describe swells with regards to the text direction (S, N, E), but to look at the actual direction in degrees, click on surf plot (view details) or the swell plots.

    Swell Plots for South Orange County (offshore swells).



    Make Sense?
    Last edited by Swellinfo; Oct 18, 2007 at 10:14 AM.

  3. #3
    Join Date
    Jul 2007
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    Easton Md
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    yes makes great sense...in terms of the height, i have a general idea, but what is the exactly the height...meaning from what point to what point is the height they are talking of? From a certain point of the water to another point?

  4. #4
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    from the trough of the swell to the crest

  5. #5
    Join Date
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    Beaner, i believe he was asking about the tidal heights.

    For tidal heights, we use a standard based on a term called Mean Lower Low Water (MLLW). So, this is a mean value of the water height at a particular location during low tide. Any variation from this level is + or 1 that MLLW value.

    So, when we say +3.5ft, this means 3.5 feet above mean lower low water. Thats why, the low tides dont generally go very far below zero.

  6. #6
    Join Date
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    Location
    Easton Md
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    so how do they determine where to make the mark to measure?