Accuracy of the weather forecast

    I've had it with trying to plan my diving with the weather forecast. When I lived in Canada I spent some time trying to figure out how accurate the weather forecast is. Summer is very short there so it was important to plan activities ahead of time. After observing the relationship between the forecast and what actually happens I figured out that the forecast is simply useless. It's useless because they're wrong %50 of the time. If they were wrong %100 of the time then you can just plan on the opposite :) but this is not the case. So I gave up on the forecast.


    Seeing as how the marine forecast is theoretically more important, unforeseen bad conditions can have a very serious effect, I thought it would be more accurate. After keeping an eye on the marine forecast over the last couple of years I came to the realization that it is not. Take today for example. Yesterday the forecast said it was going to be like 3-5ft waves. Today they changed it and it's presently this:

    Quote

    Today
    North winds 10 to 15 knots. Seas 2 to 4 feet near shore and up to 5 to 7 feet in the Gulf Stream. Intracoastal waters a light chop.

    Still nothing like what you see in the pic. And based on yesterday's conditions I thought that it might just be this way today. Funny thing is that yesterday's prediction was accurate. So again it's about %50 accuracy which is nowhere near as useful as checking the webcam first thing in the morning and deciding if I'm going diving right then and there.


    They change the forecast by the hour. I wonder if the weather forecast is more accurate today than it was 10 years ago? I remember before everyone had computers we used to call some phone number, at least thats what i remember.

    I'd say weather forecast is 80-90% right. NOAA on the other hand looks like they use a very complex algorithmic formula. I think they just divide wind speed by 5 to get a wave height in feet.


    The NOAA forecast should only have about a 10-20% bearing on your decision, it really is not important. The other 80-90% should come from local hourly/daily weather reports and from local bouy reports. The way I do it is very long to explain but you should plan your actions according to the hourly reports for that day.


    What has been going on for the past few days and what will happen in the next day or so after your planned dive is what you have to look at.


    In short, for this area, any wind direction that has an east in it should be investigated further. Any other wind generally means flat seas regardless of what NOAA says.


    It could be blowing 20-25 knots west or northwest and I won't think twice about going.

    Davie Peguero

    85-90% rough approximation. However, this is for wind and boating conditions only. For up here, as you know, to predict the viz is whole different animal.

    Quote from pargo

    85-%90 is very good. Yes viz is unpredictable. How can it be predictable when I've seen it change drastically over the course of one diving day.


    That is generally due to tides. Best viz reports are recent fishing reports from other divers or anglers. For down your way, as Davie mentioned, wind direction is always important. Also, look at the tides, lunar chart and another factor that most do not pay attention to is how far the western boundary of the Gulfstream is from shore. Up here we get some nasty ground swells that I have no idea how to predict.

    I'm with Seaweed on the westerly winds. It blows over any waves and can actually flatten the seas out. I gotta give NOAA one thing though, when we use to travel to the Bahamas often my buddy would pick up the 3-5 day reports from FIU. They were usually pretty close.
    Rolo makes a good point as for the buoys. Look at them the night before and early morning. That with the reports will give you a good idea. If your venturing into the gulf/str8's Id still look at NOAA.
    Also, the cam is good, but as you know, it could look flat, you pack your stuff, and by the time you get to the shore there's 2-4's

    Quote from Rolo

    That is generally due to tides. Best viz reports are recent fishing reports from other divers or anglers. For down your way, as Davie mentioned, wind direction is always important. Also, look at the tides, lunar chart and another factor that most do not pay attention to is how far the western boundary of the Gulfstream is from shore. Up here we get some nasty ground swells that I have no idea how to predict.


    That's a good point Rolo. I don't know how many times it's completely flat here and when you venture into the gulf you run into rollercoaster size swells.
    We need and underwater cam hooked to one of the deeper wrecks to determine visibility. I read on a thread somewhere that they have them in Bermuda and some other places.

    Quote from Toledo970

    That's a good point Rolo. I don't know how many times it's completely flat here and when you venture into the gulf you run into rollercoaster size swells.
    We need and underwater cam hooked to one of the deeper wrecks to determine visibility. I read on a thread somewhere that they have them in Bermuda and some other places.


    Yes, this is true Toledo. But I think you missed my point. I mention the gulfstream as it usually brings in clear blue water. And the closer to the reefs, the better it bodes for visibility. There have been days out of Miami, were it looked like the bahamas all over the reefs and it was clear that the water clarity was due in part to the gulf stream being near on that particular day and time along with a peak in incoming tide.

    Quote from Rolo

    Yes, this is true Toledo. But I think you missed my point. I mention the gulfstream as it usually brings in clear blue water. And the closer to the reefs, the better it bodes for visibility. There have been days out of Miami, were it looked like the bahamas all over the reefs and it was clear that the water clarity was due in part to the gulf stream being near on that particular day and time along with a peak in incoming tide.


    Yes, I agree. The water temp change is also huge when it comes to fishing, especially migratory types. We use to look for areas of water temp changes outside of the stream(but connected. Eddys(sp.?)) These areas usually hold fish.Another good thing when the stream comes in close is when it goes over large structure bottoms. It creates a push/current upwards which usually accumilates allot of bait and fish.


    Check this out it's in Bonaire 50'
    http://www.breathebonaire.com/


    By the way Dan, looked at the beach cam...... beautiful day

    Iinteresting stuff, having never owned a boat i have never looked into this.


    My old man never really cared about the currents or vis for H&L fishing, we would go based on the marine forecast.


    Talk about Golf Balls :laughing3:


    And Dan, I don't know why you haven't let more pics of you be posted on the net...... You are quite fotogenic.:laughing3::laughing3:

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